Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
DISTRIBUTION GROUNDING SWITCH TO SUPPORT DISTRIBUTED ENERGY
RESOURCES
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to grounding and/or transfer switches. More
particularly,
the present invention relates to grounding switches are used in association
with a single and
multi-phase power system. More particularly, the present invention relates to
the control of
distributed energy resources and/or associated loads.
2. Description of Related Art Including Information Disclosed Under 37 CFR
1.97
and 37 CFR 1.98.
In the U.S. and around the world, the demand for electrical power continues to
grow. At
the same time, aging transmission and distribution systems remain subject to
occasional failures.
Massive failures covering wide geographical areas and affecting millions of
people have
occurred, even in the United States which has historically enjoyed a
relatively robust electrical
power system. These problems with the capacity and reliability of the public
power grid have
driven the development of distributed energy resources. These distributed
energy resources are
small independent power generation and storage systems which may be owned by,
and located
near, consumers of electrical power.
One motivating factor is that distributed energy resources can provide more
reliable
power in critical applications. For example, the distributed energy resources
can be a backup to
the primary electrical supply. For example, an interruption of power to a
hospital can have
life-threatening consequences. Similarly, when power to a factory is
interrupted, the resulting
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losses in productivity, wasted material, and other costs, can be catastrophic.
In situations like
these, the cost of implementing distributed energy resources as a backup can
be justified.
Reliability is not only not the only driving factor in the development of
distributed energy
resources. Power from a distributed energy resource can, in some cases, be
sold back to the main
power grid. Geographically distributed sources of power, such as wind, solar,
or hydroelectric
power, may be too limited or intermittent to be used as the basis for a
centralized power plant.
By harnessing these types of geographically distributed sources using multiple
distributed energy
resources, these types of power sources can supplement or replace conventional
power sources,
such as fossil fuels, when the main power grid is available, and can provide
backup to their
owners when the main power grid is unavailable.
In this context, distributed energy resources have emerged as a promising
option to meet
consumers' current and future demands for increasingly more reliable
electrical power. Power
sources for such distributed energy resources are sometimes referred to as
"micro-sources" and
range in size and capacity from a few kilowatts up to ten megawatts. These
micro-sources can
include a variety of technologies, both supply-side and demand-side, and they
are typically
located where the energy is used.
Generally speaking, distributed energy resources can harness two broad
categories of
electrical power sources. One of these categories is DC sources, such as fuel
cells, photovoltaic
cells, and battery storage. Another broad category is high-frequency AC
sources, such as
micro-turbines and wind turbines. Both types of categories of electrical power
sources are
typically used to provide an intermediate DC voltage that may be produced
directly by DC
sources and produced indirectly from AC sources (such as by rectification). In
both types of
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sources, the intermediate DC voltage is subsequently converted to AC voltage
or current at the
required frequency, magnitude, and phase angle for use. In most cases, the
conversion from the
intermediate DC voltage to the usable AC voltage is performed by a voltage
inverter that can
rapidly control the magnitude and phase of its output voltage.
Distributed energy resources are typically designed to operate in one of two
modes: (1)
"isolation" or "island" mode and isolated from the main grid; and (2) normal
"grid" mode that is
connected to the main grid. For large utility generators, methods have been
developed to allow
conventional synchronous generators to join and to separate from the main
electrical power grid
smoothly and efficiently when needed. Because of fundamental differences
between distributed
energy resources, such as inverter-based micro-sources or small synchronous
generators, and
centralized energy resources, these existing methods are not suitable to allow
distributed energy
resources to smoothly and efficiently transition between island mode and grid
mode as the
distributed energy resources join and separate from the main power grid.
For example, the fundamental frequency in an inverter is typically derived
from an
internal clock and does not change as the system is loaded. This arrangement
is very different
from that of a synchronous generator typically used in centralized power
systems, in which the
inertia from a spinning mass determines and maintains system frequency.
Inverter-based
micro-sources, in contrast, are effectively inertia-less, so alternative
methods must be used to
maintain system frequency in an inverter-based micro-source.
Another difference between distributed energy resources and centralized energy
resources relates to communication and coordination. A centralized electrical
power utility is in a
position to monitor and coordinate the production and distribution of power
from multiple
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generators. In contrast, distributed energy resources may include independent
producers of
power with limited awareness of their communication with each other. Even if
the independent
producers of power are able to communicate with each other, there may not be
any effective way
to ensure that they cooperate.
Thus, there is a need for systems for controlling micro-sources in distributed
energy
resources to ensure these resources can connect to or isolate from the utility
grid in a rapid and
seamless fashion. There is also a need to independently control reactive and
active power.
Furthermore, it is important to be able to correct for voltage sag and system
imbalances. Further,
there is a need for control of the micro-sources based on information
available locally at the
inverter so that no communication or coordination between micro-sources is
necessary. Yet
further, there is need for a local controller at the micro-source to enable
"plug and play"
operation of the micro-source. In other words, there is a need to add micro-
sources to a
distributed energy system without changes to the control and protection of
units that are already
part of the system.
It is becoming more and more common to the place solar panels on the roof tops
of
houses. These solar panels generate electricity, not only for the house where
they are mounted,
but also for other residences. As such, it becomes a necessity for the utility
to control such
distributed energy resources. Until recent years, electricity flowed in one
way for the utility to
manage. Since the utility always had control of the generators, it was easy to
turn them on and
off whenever desired. Now electricity flows both ways. There are many small
generators (homes
with solar panels on the roof top) distributed over a wide area. Utilities
have no effective
switching capacity on such distributed generators. Currently, the utility must
rely on the capacity
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of each solar inverter (including different brands and technologies) to
understand what is going
on in the grid. In other words, they will have to make a guess as to whether
to keep generating or
to shut down. As a result, the utilities must rely upon a third-party
decision. This poses a huge
risk. If the distributed energy generation does not shut down when required by
the utility, it can
produce an overvoltage or an unsafe condition for the electrical workers. An
overvoltage can
result in destroying public or private property and creating fires. The unsafe
condition for the
electrical workers can result in a potential electrocution. As such, a need
has developed to be
able to send a clear signal to prevent the overvoltage or unsafe conditions in
a simple, easy, safe
and effective manner.
In the past, various patents have issued relating to the control of the small
distributed
energy resources. For example, U.S. Patent No. 7,687,937, issued on March 30,
2010 to Lasseter
et al., describes a method of controlling the output inverter of a micro-
source and a distributed
energy resource system. The system uses unit or zone power controllers that
reduce the operating
frequency of the inverter to increase its unit output power. This method
causes the inverter to
reach maximum output power and minimum operating frequency simultaneously.
U.S. Patent No. 8,097,980, issued on January 17, 2012 to Cyrus et al.,
provides a
distributed solar power plant and a method for connection to the existing
power grid. The method
includes generating electrical energy from a renewalable form of energy and a
plurality of
locations at which reside an electrical power line associated with an
electrical power grid. The
electrical energy generated at each location is transferred to the electrical
power line to thereby
supply electrical energy to the electric power grid.
U.S. Patent No. 8,466,581, issued on June 18, 2013 to S. Kuran, discloses a
system and
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method for providing grid-connected utility pole distributed solar power
generation. The system
includes a utility pole, an inverter, and one or more solar panels. Each of
the one or more solar
panels is mounted on the utility pole. The method includes receiving solar
energy at the solar
panels. The solar panels convert the solar energy to direct current. The DC
electrical energy is
transmitted to an inverter which is also mounted on the utility pole. The
inverter is integrated
with the solar panels to form an alternating current photovoltaic module.
U.S. Patent No. 8,473,250, issued on June 25, 2013 to Adest et al., discloses
the
monitoring of distributed power harvesting systems using DC power sources. A
monitoring
module is coupled to each side of the power sources or to each string of
serially-connected power
sources so as to monitor and collect data regarding current, voltage,
temperature and other
environmental factors at the power source. The collected data is transmitted
over a power line to
a central analysis station for analysis. Data collected from each source
indicates a malfunction or
degradation at the source. The comparison of data collected from the same
source at different
times is indicative of soiling or degradation of the source.
U. S . Patent No. 8,816,535, issued on August 26, 2014 to Adest et al.,
provides a
protection method in a distributed power system having DC power sources and
multiple power
modules which include inputs coupled to DC power sources. The power module
include outputs
coupled in series with one or more of the power modules to form a serial
string. An inverter is
coupled to the serial string. The inverter converts power input from the
string and produces
output power. When the inverter stops production of the output power, each of
the power
modules is shut down and thereby the power input to the inverter is ceased.
U.S. Patent No. 10,230,310, issued on March 12, 2019 to Loewenstern et al.,
discloses a
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safety system for photovoltaic systems. The system includes measuring
operational parameters at
certain locations within the system and/or receiving messages from control
devices indicating a
potentially unsafe condition. The system can then be disconnected or short-
circuited in response
thereto.
U. S . Patent Application Serial No. 2012/0280570, published on November 8,
2012 to
Smythe et al., teaches an electrical power distribution installation. There is
a plurality of
electrical power supply poles supporting sequentially an electric power
transmitting cable and
take-off for users from the cables. Each of the poles has a lower end embedded
in the ground and
is supported thereby to extend at least vertically therefrom. The electric
power transmitting
cables are supported at or near a top of each pole. A panel including solar
cells includes
solar-to-electric transducers distributed across the panel. Each of the panels
is attached to each of
the poles. Each has an electric circuit electrically connected to the cells
and provides translating
of electrical power from the cells to a phase and voltage matching input into
the electrical
distribution network.
Typically, with circuit breakers, the circuit to the substation can be broken
upon
application of a manual force to a button or lever of a circuit breaker or by
an automatic relay
which opens the circuit. Typically, the current is measured to the substation.
If any relay senses a
problem, the signal is transmitted to the circuit breaker so as to open the
breaker. Typically, the
relays will be maintained within the substation. The opening of the circuit
breaker will prevent
energy from being transmitted to the substation. Sometimes, the circuit
breaker is open to allow
users to work on a wind power system, on the circuit breaker, or on the
substation. Typically, the
relays will operate if the sensors sense a voltage drop.
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The interruption of electrical power circuits has always been an essential
function,
especially in cases of overloads or short circuits, when immediate
interruption of the current flow
becomes necessary as a protective measure. In earliest times, circuits could
be broken only by
separation of contacts in air followed by drawing the resulting electric arc
out to such a length
that it can no longer be maintained. This means of interruption soon became
inadequate and
special devices, termed "circuit breakers", were developed. The basic problem
is to control and
quench the high power arc. This necessarily occurs at the separating contacts
of a breaker when
opening high current circuits. Since arcs generate a great deal of heat energy
which is often
destructive to the breaker's contacts, it is necessary to limit the duration
of the arc and to develop
.. contacts that can withstand the effect of the arc time-after-time.
A vacuum circuit breaker uses the rapid dielectric recovery and high
dielectric strength of
the vacuum. The pair of contacts are hermetically sealed in the vacuum
envelope. An
actuating motion is transmitted through bellows to the movable contact. When
the electrodes
are parted, an arc is produced and supported by metallic vapor boiled from the
electrodes.
Vapor particles expand into the vacuum and condense on solid surfaces. At a
natural current
zero, the vapor particles disappear and the arc is extinguished.
In the past, in association with wind farm systems, when the circuit breakers
are open, the
collection circuit voltage would be interrupted and a transient overvoltage
situation could occur
in the collection circuit. In the overvoltage situation, the high transient
voltage and the collection
circuit line will "backup" through the circuit into the electronics associated
with the wind energy
generators. As a result, this transient overvoltage could cause damage to the
circuitry associated
with the energy generators and other circuitry throughout the system. As such,
there is a need to
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hold (within acceptable) limits any overvoltage which occurs when the circuit
breaker is to be
opened.
When a single line-to-ground fault occurs, there are basically two objectives
for
protecting the collection circuit. The first objective is clearing the fault
from the grid to reduce
both the incident energy and the time that personnel and equipment are exposed
to the fault
current sourced from the transmission system. When the feeder breaker operates
first and clears
the power generator from the fault, high current from the transmission system
is limited in time.
However, the temporary overvoltage in the collection circuit can present a
problem since the
generator is islanded. The second objective is to get the generators to shut
down without
islanding. This object competes with the first objective of quickly opening
the feeder breaker. It
takes approximately two hundred milliseconds for the signal to reach the
generators in order to
shut the generators down. Islanding occurs when all or a portion of the power
generated by the
power resource becomes electrically isolated from the remainder of the
electrical power system.
For example, in large collection circuits producing power at twenty-four
megawatts separates,
severe islanding can occur. Some designers place a grounding transformer on
the collection
circuit when trying to avoid temporary overvoltage. In certain cases, however,
the grounding
transformer will not be effective when it comes to reducing temporary
overvoltage and
subsequent damage to the lightning arrestors. Grounding transformers connected
to the collection
circuits provide a zero sequence path to ground that does not provide a
positive or negative
sequence path to ground. Grounding transformers provide a relatively low zero
sequence
impedance. However, the impedance is not low enough to prevent a severe
voltage rise during a
fault followed by severe islanding event.
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Faults in collection circuits happen and the longer that a fault continues,
the more damage
will occur. Although communication systems are fast, they do not process
information
instantaneously. Therefore, communication plays a very important role in
protecting the
collection circuit. A signal over a dedicated communication channel, such as a
fiber, takes time
to complete. This delay is called "latency". Delays from the initiation of a
fault on the collection
circuit to the time when the equipment is separated or isolated from the fault
is called "clearing
time". When protecting a collection circuit, among the objectives to be
accomplished, it is
necessary to clear the fault from the grid and to clear the fault from the
individual generators.
The use of the transfer trip tool can be used. "Transfer trip" means the
opening of a circuit
breaker from a remote location by means of a signal over a communication line.
When using
transfer trip, if the fault is cleared by the grid by tripping the feeder
breaker as fast as possible
and if the feeder breakers take longer than desired, the entire collection
circuit is exposed to
temporary overvoltage. If the circuit breaker is intentionally delayed in
order to match the
opening of the circuit breaker and the generator breakers, the feeder is
exposed to incident
energy and eventually the temporary overvoltage will occur if the delay is not
sufficient.
The Federal Energy Regulatory Commission (FERC) has Reliability Standard
PRC-024-1. Relay settings in wind and solar power plants must comply with the
standard. The
standard states that each generator that has generator voltage protective
relaying activated to trip
its applicable generating unit(s) shall set its protective relaying such that
the generator voltage
.. protective relaying does not trip the applicable generating unit(s) as a
result of voltage excursion
(at the point of interconnection) caused by an event on the transmission
system external to the
generating plant that remains within a "no trip zone" of a time duration
curve. The point of
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interconnection means that the transmission (high-voltage) side of the
generator step-up
transformer or collector circuit transformer. Many types of faults occur
within or outside of the
wind power or solar power plant. An internal fault is considered as a single
line fault to ground
while an external fault is a three-phase bolted fault. Conventional ground
transformers provide
no way for the operator to ascertain whether the fault is internal or
external. As a result,
operation within the "no trip zone" may be required even though the fault is
internal of the wind
or solar farm. As such, a need has developed in order for the operator to
ascertain whether the
fault is internal or external of the wind or solar farm system.
In the past, various patents and patent application publications have issued
with respect to
such circuit breakers. For example, U.S. Patent. No. 5,612,523, issued on Mar.
18, 1997 to
Hakamata et al., teaches a vacuum circuit-breaker and electrode assembly. A
portion of a highly
conductive metal member is infiltrated in voids of a porous high melting point
metal member.
Both of the metal members are integrally joined to each other. An arc
electrode portion is formed
of a high melting point area in which the highly conductive metal is
infiltrated in voids of the
high melting point metal member. A coil electrode portion is formed by
hollowing out the
interior of a highly conductive metal area composed only of the highly
conductive metal and by
forming slits thereon. A rod is brazed on the rear surface of the coil
electrode portion.
U.S. Patent No. 6,048,216, issued on April 11, 2000 to Komuro, describes a
vacuum
circuit breaker having a fixed electrode and a movable electrode. An arc
electrode support
member serves to support the arc electrode. A coil electrode is contiguous to
the arc electrode
support member. This vacuum circuit breaker is a highly reliable electrode of
high strength
which will undergo little change with the lapse of time.
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U.S. Patent No. 6,759,617, issued on July 6, 2004 to S. J. Yoon, describes a
vacuum
circuit breaker having a plurality of switching mechanisms with movable
contacts and stationary
contacts for connecting/breaking an electrical circuit between an electric
source and an electric
load. The actuator unit includes at least one rotary shaft for providing the
movable contacts with
dynamic power so as to move to positions contacting the stationary contacts or
positions
separating from the stationary contacts. A supporting frame fixes and supports
the switching
mechanism units and the actuator unit. A transfer link unit is used to
transfer the rotating
movement of the rotary shaft to a plurality of vertical movements.
U.S. Patent No. 7,223,923, issued on May 28, 2007 to Kobayashi et al.,
provides a
vacuum switchgear. This vacuum switchgear includes an electro-conductive outer
vacuum
container and a plurality of inner containers disposed in the outer vacuum
container. The inner
containers and the outer container are electrically isolated from each other.
One of the inner
vacuum containers accommodates a ground switch for keeping the circuit open
while the
switchgear is opened. A movable electrode is connected to an operating
mechanism and a fixed
electrode connected to a fixed electrode rod. Another inner vacuum container
accommodates a
function switch capable of having at least one of the functions of a circuit
breaker, a disconnector
and a load switch.
U.S. Patent No. 3,883,706, issued on May 13, 1975 to K. Glaser, describes a
multiple
rotary wafer type switch with axial bridging contacts and multiple wafer
connecting rings. There
are at least two circular insulating members each having a central opening.
The members are
assembled with end faces thereof being in contact and their openings in
registry. Radially
inwardly extending contact tongues are embedded in the insulating members for
cooperation
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with the rotor having contact bridges arranged in the central openings. An
elastically deformable
connecting ring is disposed in the central openings and axially overlaps the
insulating member.
U.S. Patent No. 4,016,385, issued on April 5, 1977 to I. Golioto, teaches a
high-voltage
transfer switch with a cam controlled overlap during transfer. This transfer
switch selectively
transfers an electrical load from one high-voltage source to another. The
transfer switch includes
a shaft connected to a handle. There are two circular slotted cams spaced
close to opposite ends
of the shaft. Cam followers are connected to opposite ends of a follower bar
and are inserted in
the cam slot. The follower bars connected to the cam follower are connected to
vacuum
interrupter contacts. The transfer switch is constructed so that as the cam is
rotated, the contacts
connecting one high-voltage source to the electrical load are closed and as
the cam is continued
to be rotated, the contactors of the previously connected high-voltage supply
are subsequently
released.
U.S. Patent No. 6,462,296, issued on October 8, 2002 to Boettcher et al.,
describes a
circuit breaker arrangement and, in particular, and air-insulated medium-
voltage switching
arrangement having circuit breaking features, disconnection features and
grounding features. The
circuit breaker arrangement includes a switching module that is formed from
function-oriented
modular components. The modular components include a base module component, a
pole
module component and a drive module component. The base module component is
fixedly
connected with the drive module component. The pole module component is
arranged so as to be
movable along a straight line.
U.S. Patent No. 6,951,993, issued on October 4, 2005 to Kikukawa a et al.,
provides a
vacuum switch having a vacuum container, a grounding switch, and a load switch
disposed in a
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container. An external connection conductor is disposed in the vacuum
container and connected
electrically inside and outside of the vacuum container. The grounding switch
and the external
connection conductor are electrically connected to each other in the vacuum
container.
U.S. Patent No. 7,724,489, issued on May 25, 2010 to the present inventor,
describes a
circuit breaker with a high-speed mechanically-interlocked grounding switch.
The subject matter
of this patent is described hereinbelow.
U.S. Patent No. 8,174,812, issued on May 8, 2012 to the present inventor,
describes a
mechanically interlocked transfer switch that has first, second and third
electrical terminals
extending outwardly from a housing. A first vacuum bottle is positioned in the
housing and has a
pair of contactors therein. A second vacuum bottle is positioned in the
housing and has a pair of
contactors therein. A mechanical linkage is movable between a first position
and a second
position. The first position electrically connects the first electrical
terminal to the second
electrical terminal. The second position electrically connects the third
electrical terminal to the
second electrical terminal. The first vacuum bottle in the second vacuum
bottle are longitudinally
aligned. The mechanical linkage is interposed between the first and second
vacuum bottles.
U.S. Patent No. 8,467,166, issued on June 18, 2013 to the present inventor,
describes a
circuit breaker and impedance grounding switch having a first electrical
terminal, a second
electrical terminal, a third electrical terminal, a first vacuum bottle with a
pair of contactors
therein, a second vacuum bottle with a pair of contactors therein, and a
mechanically interlocked
linkage being electrically interconnected to the second electrical terminal
and being movable
between a first stable position and a second stable position. One of the pair
of contactors of the
first vacuum bottle is connected to the first electrical terminal. One of the
pair of contactors of
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the second vacuum bottle is electrically interconnected to the third
electrical terminal. The
linkage has a temporary position between the first and second stable positions
electrically
connecting simultaneously the first electrical terminal to the second
electrical terminal and a
third electrical terminal to the second electrical terminal.
Japanese Patent No. 2000341858, published on December 8,2000, describes a
device and
method for switching a power supply. This device switches the power supply
received by a dual
system at high speed by opening the pole of a primary switch at a current zero
point formed out
of current supplied by primary and secondary power systems. It then turns off
the primary switch
from a primary power system and steps down the voltage to normal operating
voltage. After a
pole closing command is sent from a switching control part to the switch of
the secondary power
system, the pole closing of the switch is completed. A pole opening command is
outputted from
the switching control part to a primary switch. The pole is open so as to cut
off current at a
current zero point formed out of currents running from the primary and
secondary current
systems.
Japanese Patent No. 05174676, published on June 26, 2000, teaches a power
source
change-over switch which simultaneously carries out change-over switching for
selectively
switching first and second power sources to connect them to the load. A first
contact is provided
between a first power source and a load. A second contact is switched
complementarity to the
first contact and is provided between the second power source and the load.
The first contact is
composed of a contact pair of a first fixed contact and a first moving
contact. The second contact
is composed of a contact pair of a second fixed contact and a second moving
contact.
Japanese Patent No. 07161265, published on January 26, 2004 describes an
electrical
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power switching device that performs space saving without generating arc short-
circuiting. A
first auxiliary contactor is formed adjacent to a main contactor. A second
auxiliary contactor is
formed adjacent to a second main contactor when a switching command is given,
the first main
contactor is opened. Just after the first main contactor is opened and just
before the auxiliary
.. contactor is opened, a voltage drop is generated because the first current
control element is
inserted between the first power supply and the load.
Japanese Patent No. 2006019193, published on January 19, 2006, describes a
switching
device that improves the insulation properties of the switching device to
which a number of
vacuum valves are connected serially. The device has a pair of contacts which
are freely
connected or disconnected. Two or more serially connected vacuum valves having
an arc shield
of intermediate potential is enclosed around the pair of contacts. Voltage
share elements are
connected in parallel between a contactor, the vacuum valve and the arc
shield. An operating
mechanism is provided for opening and closing the vacuum valve simultaneously.
Japanese Patent No. 11162303, published on June 18, 1999, describes a
switchgear
intended to reduce the size of the switchgear. A fixed electrode for a main
circuit is provided at
one end of the inside of one vacuum ground vessel while a fixed electrode for
a ground circuit is
provided at the other end thereof. The number of each of the electrodes
corresponds to the style
of a single phase or multiphase system. A moving conductor connected to a load
side conductor
for each phase is insulation-supported between the fixed electrodes so that it
can move linearly.
.. A movable electrode for the main circuit is provided at one end of the
moving conductor while
the movable electrode for the ground circuit is provided at the other end
thereof. A driver for
moving the moving conductor is provided at the other side of the vacuum ground
vessel.
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European Patent Application No. 1 538 650, published on June 8, 2005, teaches
an
isolator/circuit breaker device for electric substations. The device comprises
a casing, at least one
circuit breaker, at least one line isolator having a fixed isolator contact, a
line isolator actuating
shaft for actuating the line isolator, at least one earthing isolator, a
circuit breaker actuating shaft
for actuating at least one circuit breaker, and a lever connected to a
conductor rod cooperating
with movable circuit breaker contacts. The conductor rod engages with the
fixed isolator contact
in a closing position. The device further includes a resilient member
cooperating with the
conductor rod in order to transfer correct pressing loads to the movable
contacts.
It is an object of the present invention to provide a distribution grounding
switch that
protects against overvoltages.
It is another object of the present invention to provide a distribution
grounding switch
which avoids damaging or destroying private and public property.
It is another object of the present invention to provide a distribution
grounding switch
which increases safety for electrical workers.
It is another object of the present invention to provide a distribution
grounding switch
that provides utilities with switching capabilities on distributed energy
resources.
It is another object of the present invention to provide a distribution
grounding switch
that avoids overvoltages during transitions.
It is still another object of the present invention to provide a distribution
grounding
switch which provides a clear shut-down signal to the user.
It is still another object of the present invention to provide a distribution
grounding
switch that is managed by the utilities.
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It is still further object of the present invention to provide a distribution
grounding switch
that causes transitions or commutations in a minimal amount of time.
It is a further object of the present invention to provide a distribution
grounding switch
that reduces prolonged transient overvoltages.
It is another object of the present invention to provide a distribution
grounding switch
that helps utility operators identify and clear transient faults.
It is still a further object of the present invention to provide a
distribution grounding
switch which improves distributed energy resource islanding.
It is still another object of the present invention to provide a distribution
grounding
switch that improves surge protection.
It is still another object of the present invention to provide a distribution
grounding
switch that improves distribution stability and reliability.
It is a further object of the present invention to provide a distribution
grounding switch
that reduces maintenance costs.
It is further object of the present invention to provide a distribution
grounding switch that
rapidly detects an undervoltage or shutdown.
It is still another object of the present invention to provide a distribution
grounding
switch that provides the utility with a means to de-energize the lateral from
the primary source.
These and other objects and advantages of the present invention will become
apparent
from a reading of the attached specification and appended claims.
BRIEF SUMMARY OF THE INVENTION
The present invention is a transfer switch apparatus that has a first
electrical terminal
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adapted for connection to a mains line, a second electrical terminal adapted
for connection to a
lateral line, a first vacuum bottle having a pair of contactors therein, a
second vacuum bottle
having a pair of contactors therein, and a mechanical linkage cooperative with
one of the pair of
contactors of the first vacuum bottle and one of the pair of contactors of the
second vacuum
bottle so as to cause the pair of contactors of the first vacuum bottle to
close while generally
simultaneously causing the pair contactors of the second vacuum bottle to open
and so as to
cause the pair of contactors of the first vacuum bottle to open and generally
simultaneously
caused the pair of contactors the second vacuum bottle to close. One of the
pair of contactors of
the first vacuum bottle is electrically connected or interconnected to the
first electrical terminal.
Another of the pair of contactors of the first vacuum bottle is electrically
connected or
interconnected to the second electrical terminal. One of the pair of
contactors of the second
vacuum bottle is electrically connected or interconnected to the first
electrical terminal while
another of the pair contactors of the second vacuum bottle is electrically
connected or
interconnected to ground or neutral.
One of the pair of the contactors of the first vacuum bottle has a first rod
extending
therefrom. One of the pair of contactors of the second vacuum bottle has a
second rod extending
therefrom. The mechanical linkage comprises a yoke pivotally mounted at a
pivot point. The first
rod is mounted to the yoke of one side of the pivot point. The second rod is
mounted to the yoke
on the opposite side of the pivot point. The mechanical linkage is positioned
in a housing. The
yoke is pivotally mounted to or within the housing.
An actuator is cooperative with the mechanical linkage. The actuator
selectively acts on
the mechanical linkage so as to cause the pair of contactors of the first
vacuum bottle to close
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while the pair of contactors of the second vacuum bottle open. The actuator is
cooperative with
the mechanical linkage also so as to cause the pair of contactors the first
vacuum bottle to open
while the pair of contactors of the second vacuum bottle close. A magnetic
actuator selectively
applies an electromagnetic force to an actuator rod so as to cause the
actuator rod to move in at
.. least one direction. In particular, the actuator comprises a permanent
magnet positioned adjacent
to the magnetic actuator. The permanent magnet exerts a force on the actuator
rod such that the
actuator rod is retained in a fixed position after moving in the one
direction. The magnetic
actuator is cooperative with the permanent magnet or with the actuator rod so
as to release the
actuator rod from the permanent magnet such that the actuator rod moves in an
opposite
direction. A resilient member is connected or interconnected to the actuator
rod so as to urge the
actuator rod in the opposite direction.
The mechanical linkage has a pin member pivotally mounted thereto. The pin
member is
pivotally mounted to the actuator. One of the pair of contactors of the first
vacuum bottle has a
first rod. The pin member is pivotally mounted to only one of the sides of the
yoke. The pin
member is also pivotally mounted to the actuator rod. The actuator rod is a
hinge member
extending at an end of the actuator rod. The hinge manager member is pivotally
connected to the
pin member. An indicator is connected or interconnected to the pin member. The
indicator
indicates a position of the pair of contactors of either of the first and
second vacuum bottles. The
indicator has a display that indicates a position of the pair of contactors of
either of the first and
second vacuum bottles. A movement of the pin member causes the indicator to
show the status
of the grounding switch apparatus.
The present invention has a first current transformer connected between the
first electrical
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terminal and the first and second vacuum bottles. The first current
transformer is adapted to
detect a variation of current flowing through the first current transformer.
First current
transformer is cooperative with the actuator such that the actuator causes a
movement of each of
the first and second contactors in the first and second vacuum bottles upon
detection of the
current condition in the first current transformer. A second current
transformer is connected to at
least one of the pair of contactors of the second vacuum bottle. The second
current transformer is
adapted to determine if a flow of current exists after the mechanical linkage
causes the pair of
contactors of the second vacuum bottle to close in order to ground or
neutralize the current. An
arrestor is cooperative with the pair of contactors of the first vacuum bottle
so as to protect the
mains line or the lateral line from overvoltages when the pair of contactors
of the first vacuum
bottle separate.
In the present invention, a shock absorber is connected to at least one of the
sides of the
yoke. The shock absorber is adapted to absorb shocks caused by movement of the
first and
second rods of the pair of contactors of the first and second vacuum bottles.
The magnetic actuator has a power source connected thereto so as to supply
power to the
magnetic actuator in order to move the actuator rod. The present invention
further includes a
sensor that senses the current flowing through the pair of contactors of the
first and second
vacuum bottles. The sensor is cooperative with the power source so as to
actuate the magnetic
actuator. An arm is connected or interconnected to the yoke. The arm is
positioned outwardly of
the housing. The arm is actuatable exterior of the housing and adapted to
allow a person to
manually move the yoke in order to position the pair of contactors of either
the first and second
vacuum bottles.
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In the present invention, a mains line is connected to the first electrical
terminal. A lateral
line is connected to the second electrical terminal. A ground line is
connected to one of the pair
of contactors of the second vacuum bottle.
When the transfer switch of the present invention operates, the main breaker
opens and
disconnects the lateral from the main line. During transition, there is no
overvoltage (since there
is an arrestor that caps the voltage) and then ground closes so as to connect
the lateral to ground.
This gives a very clear shut-down signal to every generator connected to the
lateral. In the
eventuality that one or more of the generators stay connected, the voltage is
zero. As such, there
is no damage that can be done. The transfer switch apparatus can be installed
on the grid so as to
be managed by the utility. This gives the utility full control on the
operation of the various
distributed energy resources.
The commutation process begins with the ground closed and the main open. The
opening
spring keeps the ground vacuum interrupter closed and the main vacuum
interrupter open. When
the magnetic actuator is energized for a short period of time, with
electricity provided by an
outside source, the actuator rod will pull the opening spring and all the
components will move.
Once the rod within the magnetic actuator gets to the end of the stroke, the
permanent magnet
catches the rod and holds the rod in position without the need for maintaining
the electrification
of the magnetic actuator. At this time, the main breaker is closed and the
ground is open.
The magnetic actuator is then energized once again for a short period of time
but in an
opposite direction so as to neutralize the permanent magnet and release the
opening spring. This
pulls the mechanism into an opposite direction. The shock absorber allows a
soft end of the
stroke and avoids bounces which could create re-strikes. The main breaker is
now open and the
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Date Recue/Date Received 2021-05-26
ground closed. This is (1) a clear shut-down signal to every distributed
energy resource that is
connected to the lateral; (2) a safe environment for utility workers to work
because the system is
grounded; and (3) a way to prevent disasters and fires since the lines are de-
energized.
The current transformer located at the top of the main breaker will detect any
variation on
the intensity of the current flowing through it. If there is a large increase
in current, the current
transformer will detect such a large increase and send a signal to the
protection relay attached to
and sends a tripping signal to open the magnetic actuator. The current
transformer located
between the two poles will inform, after the system is grounded, if there is
still a flow of
electricity. This is important information for utility and electrical workers
that are working on the
system.
The mechanical commutation process can take up to twenty milliseconds, either
for
closing or opening. As such, this "generally simultaneously" opening or
closing can be construed
as being instantaneously or up to a twenty millisecond delay. During the
opening process,
contacts on the main vacuum interrupter move apart. At the beginning of this
movement, there is
.. still flow of electricity. However, at some point the electricity flow
stops. When the current stops
flowing, temporary over-voltages will happen for a short period of time until
the ground breaker
closes. At this small period of time, if the transient overvoltages are too
high, this could cause
damage to the system. The arrestor limits these transient overvoltages during
this period of time.
This foregoing Section is intended to describe, with particularity, the
preferred
embodiment of the present invention. It is understood that modifications to
this preferred
embodiment can be made within the scope of the present claims. As such, this
Section should not
to be construed, in any way, as limiting of the broad scope of the present
invention. The present
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Date Recue/Date Received 2021-05-26
invention should only be limited by the following claims and their legal
equivalents.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIGURE 1 is a side elevational view showing a utility pole having the
distribution
grounding switch of the present invention installed thereon.
FIGURE 2 is a schematic showing the system of the present invention as used in
association with relays to the utility.
FIGURE 3 is an upper perspective view of the distribution grounding switch of
the
present invention.
FIGURE 4 is a cross-sectional view showing the distribution grounding switch
of the
present invention with the mains closed and the grounding open.
FIGURE 5 is a cross-sectional view of the distribution grounding switch of the
present
invention with the mains open and the grounding closed.
FIGURE 6 is a cross-sectional end view of the distribution grounding switch of
the
present invention of FIGURE 5.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGURE 1, there is the system 10 of the present invention. The
system 10
includes a utility pole 12 having a crossbeam 14 at a top thereof and a mains
line 16 positioned
on the crossbeam 14. The mains line 16 will be ultimately connected to a
utility. The distribution
grounding switch 18 is supported on the pole 12 below the crossbeam 14.
Ultimately, a line 20
extends from the mains line 16 to a cutout or to a fuse 22. Line 24 extends
from the fuse 22 to a
potential transformer 26. Potential transformer 26 is supported on the pole 12
generally opposite
to the distribution grounding switch 18. Lateral line 28 is connected to the
pole 12. Lateral line
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Date Recue/Date Received 2021-05-26
28 has a branch 30 that is connected to the distribution grounding switch 18.
The mains line 16 is
ultimately connected by branch line 32 to the distribution grounding switch
18. A control or
relay 32 is supported by the pole 12 in a conventional manner. A neutral or
grounding line 36 is
connected or interconnected to the distribution grounding switch 18.
Ultimately, a ground rod 38
extends downwardly from the bottom of the pole 12.
FIGURE 2 shows the configuration of the system 10 of the present invention.
System 10
allows the utility to have control and monitoring of the distributed energy
resources. The
distribution grounding switch 18 is illustrated as having a mains vacuum
interlock 40 and a
grounding vacuum interlock 42 therein. A mechanical linkage 44 connects the
mains vacuum
interrupter 40 to the grounding vacuum interrupter 42 (in the matter to be
described hereinafter).
Relay 34 is connected to a line 46 extending to the mains line 16. A potential
transformer 26 is
positioned on line 26. Relay 34 is connected by lines 48 and 50 to lateral
line 30. Lateral line 30
has a fuse 52 thereon. Fuse 52 is located between the single phase grounding
switch 18 and the
mains line 16. A first current transformer 54 extends from line 48 to the
relay 34. A second
current transformer 56 is connected to the line 50 and extends to the relay
34. As will be
described hereinafter, the first current transformer is located on top of the
main breaker and will
detect any variation on the intensity of the current flowing through it. If
there is a huge increase
in current, the current transformer 54 will detect it and send a signal to the
protection relay
attached to it. This ultimately sends a tripping signal to the magnetic
actuator (to be described
hereinafter). The second current transformer 56 is located between the two
poles so as to
determine if the system is grounded.
The distribution grounding switch 18 has the mains vacuum interrupter 40
connected to
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Date Recue/Date Received 2021-05-26
the mains line 16 and to the lateral line 30. The grounding vacuum interrupter
42 is connected to
the mains line 16 and to ground line 36 and/or to ground rod 38. The
mechanical linkage 44 will
cause the mains vacuum interrupter 42 to open when a fault condition occurs.
This generally
simultaneously causes the grounding vacuum interrupter 42 to close so that the
power from the
mains line 16 flows to ground rod 38 or to neutral line 36. Alternatively,
when a no-fault
condition is sensed, then the mains vacuum interrupter 40 will remain closed
so that power from
the lateral line 30 will flow to the mains line 16.
Relay 34 is configured to sense the condition of power flowing to the utility
from the
distributed energy resources connected to lateral line 30. Relay 34 will
inform the utility of an
under-voltage 27, an over-voltage 59, a directional power 32 and an inverse
time over-current 50
and 51. As such, relay 34 facilitates the ability of the utility to send the
shutdown signal to the
distribution grounding switch 18 and ultimately to the distributed energy
resources connected to
the lateral line 30. As such, if it is necessary to shut down the distributed
energy resources, the
shutdown signal is sent through the mains line 16 to the distribution
grounding switch 18 so that
power is no longer transmitted from the distributed energy resource along
lateral line 30 to the
mains line 16 and so that the power flows to ground.
FIGURE 3 shows the distribution grounding switch 18 of the present invention.
As can
be seen, the distribution grounding switch 18 has a first electrical terminal
60 connected to the
mains line 16. There is a second electrical terminal 62 connected to the
lateral line 30. The mains
vacuum interrupter 40 is connected to the first electrical terminal 60 and the
second electrical
terminal 62 so that power can flow therebetween. The grounding vacuum
interrupter 42 is
illustrated as connected to the second electrical terminal 62 and connected to
ground bar 38.
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Date Recue/Date Received 2021-05-26
Alternatively, as shown in FIGURE 2, the grounding vacuum interrupter 42 can
also be
connected to a neutral or grounding line.
FIGURE 3 shows that there is a housing 64 positioned at the bottom of the
mains vacuum
interrupter 40 and the grounding vacuum interrupter 42. Housing 44 will
contain the mechanical
linkage therein (to be described hereinafter). An arm 66 extends outwardly of
the housing 64.
The arm 66 will be connected or interconnected to the linkage within the
interior of the housing
44 (to be described hereinafter). The arm 66 is actuatable exterior of the
housing 64 so as to
allow a person to manually move the mechanical linkage in order to set a
position of the pair of
contactors of either the mains vacuum interrupter 40 or the grounding vacuum
interrupter 42. An
indicator 68 is pivotally mounted on the exterior of the housing 64. Indicator
68 is a display that
indicates a position of the pair of contactors of either the mains vacuum
interrupter 44 or the
grounding vacuum interrupter 42. A movement of the indicator 68 shows the
status of the
distribution grounding switch 18.
An arrestor 70 is connected to the electrical terminal 62. Arrestor 70 is
cooperative with
the pair of contactors of the mains vacuum interrupter 40 or with a pair of
contactors of the
grounding vacuum interrupter so as to protect the mains line or the lateral
line from transient
overvoltages when the pair of contactors of the mains vacuum interlock 40
separate.
FIGURE 4 is a cross-sectional view of the distribution grounding switch 18 of
the present
invention. This distribution grounding switch 18 has a first electrical
terminal 60 adapted to be
connected to the mains line 16. The first current transformer 54 is connected
to the first terminal
60. The second electrical terminal 62 is adapted to be connected to the
lateral 30. A second
current transformer 56 is positioned adjacent to the second electrical
terminal 62. The mains
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Date Recue/Date Received 2021-05-26
vacuum interrupter 40 comprises a first vacuum bottle 72 having a pair of
contactors 74 and 76
therein. Contactor 74 is electrically connected or interconnected to the first
electrical terminal 60.
The contactor 76 is electrically connected or interconnected to the second
electrical terminal 62.
The grounding vacuum interrupter42 has a second vacuum bottle 78 therein.
Second
vacuum bottle 78 has a pair of contactors 80 and 82 therein. Contactor 80 is
electrically
connected to ground bar 38. The second contactor 42 will ultimately be
electrically connected or
interconnected to the second electrical terminal 62.
A mechanical linkage 84 is positioned in the interior of housing 64.
Mechanical linkage
84 is cooperative with one of the contactors 74 and 76 of the first vacuum
bottle 72 and one of
the pair of contactors 80 and 82 of the second vacuum bottle 78 so as to cause
the pair of
contactors 74 and 76 of the first vacuum bottle 72 to close while generally
simultaneously
causing the pair of contactors 80 and 82 of the second vacuum bottle 78 to
open (as shown in
FIGURE 4). In this configuration, power from the lateral line 32 can flow to
and from the mains
line 16. In this circumstance, the system is operating properly and power from
the distributed
energy resources are being delivered to the utility.
The contactor 76 of the second vacuum bottle 72 has a rod 86 extending
therefrom.
Contactor 82 of the second vacuum bottle 78 has a rod 88 extending therefrom.
The mechanical
linkage 84 includes a yoke 90 pivotally mounted at a pivot point 92 within the
housing 64. The
rod 86 has one end mounted at pivot 94 the yoke 90 on one side of the pivot
.92. The rod 88 is
.. connected to pivot 96 of the yoke 90 on an opposite side of the pivot point
92. Yoke 90 operates
in a seesaw manner such that when a downward force is applied to the yoke 90
on one side of the
pivot point 92, the opposite side of the yoke 90 will create an upward force.
In FIGURE 4, it can
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Date Recue/Date Received 2021-05-26
be seen that the yoke 90 is pivoted such that the rod 86 moves upwardly so as
to close the pair of
contactors 74 and 76 of the first vacuum bottle 72 generally simultaneously
with the opening of
the pair of contactors 80 and 82 of the second vacuum bottle 78.
The distribution grounding switch 40 has an actuator 98 that is cooperative
with the
mechanical linkage 84. The actuator 98 selectively acts on the mechanical
linkage 84 so as to
cause the pair of contactors 74 and 76 of the first vacuum bottle 72 to close
while the pair of
contactors 80 and 82 of the second vacuum bottle 78 open. The actuator 98
includes a magnetic
actuator 100 that selectively applies an electromagnetic force onto an
actuator rod 102 so as to
cause the actuator rod 92 to move in one direction. In FIGURE 4, it can be
seen that the
magnetic actuator 100 has caused the actuator rod 102 to move toward the right
such that an end
of the actuator rod 102 engages with a permanent magnet 104. Permanent magnet
104 is
positioned adjacent to the magnetic actuator 100. The permanent magnet 104
exerts a magnetic
force onto the actuator rod 102 such that the actuator rod 102 is retained in
a fixed position after
moving in one direction. The magnetic actuator 100 is cooperative with the
permanent magnet
104 or with the actuator rod 102 so as to release the actuator rod 102 from
the permanent magnet
100 and such the actuator rod 102 can move in an opposite direction. A
resilient member 106 is
connected or interconnected to the actuator rod 102 so as to urge the actuator
rod in the opposite
direction. The resilient member 106 can be a spring mounted to a side of the
housing 64.
The mechanical linkage 84 has a pin member 108 pivotally mounted thereto. The
pin
member 104 will be pivotally mounted to the actuator 98. In particular, the
pin member 108 (as
will be described hereinafter) will be connected by a pivoting linkage to the
actuator rod 102.
The pin member 108 is illustrated as pivotally mounted to only one side of the
yoke 90. Pin
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Date Recue/Date Received 2021-05-26
member 108 is particularly shown as connected to pivot 96 of yoke 90.
Ultimately, pin member
108 will move upwardly (with the movement of the actuator rod 102) so as to
urge the rod 88
upwardly such that the contactors 80 and 82 of the ground vacuum interlock 42
to close. In
particular, the actuator rod 102 will have a hinge member 110 pivotally
mounted to an end of the
actuator rod 102. As will be described hereinafter, the hinge member 110 will
also be pivotally
connected to the pin member 108 at an end opposite the pivot 96 of the yoke
90.
An indicator 112 is connected or interconnected to the pin member 108. The
indicator
112 has a display 114 that indicates a position of the pair of contactors of
either of the first
vacuum bottle 72 or the second vacuum bottle 78. A movement of the pin member
108 can cause
the indicator 112 to show a status of the distribution grounding switch 40.
The first current transformer 54 is connected between the first electrical
terminal 60 and
the first and second vacuum bottles 72 and 74. The first current transformer
54 is adapted to
detect a variation of current flowing through the first current transformer
54. The first current
transformer 54 is cooperative with the actuator 98 such that the actuator
causes a movement of a
contactor of each of the pair of contactors in the first and second vacuum
bottle 72 and 78 upon
detection of a current condition in the first current transformer 54.
The second current transformer 56 is connected to at least one of the pair of
contactors of
the second vacuum bottle 78. The second current transformer 56 is adapted to
determine if a flow
of current exists after the mechanical linkage 84 causes the pair of
contactors 80 and 82 of the
second vacuum bottle 78 to close in order to ground or neutralize the current.
A shock absorber 116 is connected to at least one of the sides of the yoke 90.
The shock
absorber 116 is in the nature of a spring that is adapted to absorb shock
caused by the movement
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Date Recue/Date Received 2021-05-26
of the first rod 86 or the second rod 88.
The magnetic actuator will have a power source connected thereto so as to
supply power
to the magnetic actuator 100 in order to move the actuator rod 102. A sensor
(in the nature of the
first current transformer 54 the second transformer 56) will sense the current
flowing through the
pair of contactors of the first vacuum bottle 72 and the second vacuum bottle
78. The sensor is
cooperative with the power source so as to actuate the magnetic actuator 100.
An arm 116 is connected or interconnected to the yoke 90. The arm 116 is
positioned
outwardly of one side of the housing 64. The arm 116 is actuatable exterior of
the housing 64
and adapted to allow a person to manually move the yoke 90 in order to set a
position of the pair
of contactors of either of the first vacuum bottle 72 or the second vacuum
bottle 78. The arm 116
is also cooperative with the pin member 108 so as to allow the indicator 112
to appropriately
move on the display 114.
In FIGURE 4, it can be seen that power is flowing through the lateral line 30
and through
the mains line 16. In this configuration, if power is generated by distributed
energy resource, it
can be delivered through the second electrical terminal 62 and into the mains
vacuum interrupter
40. Since the contactors 74 and 76 of the first vacuum bottle 72 are closed,
this power will flow
therethrough and to the first electrical terminal 60. If the transformer 54
should sense a fault in
the current or sense a signal from the utility to close the distributed energy
resource or resources,
the contactor 74 and 76 in the first vacuum bottle 72 will separate while
generally
simultaneously the contactors 80 and 82 of the first second vacuum bottle 78
will close in the
manner shown in FIGURE 5 hereinafter.
FIGURE 6 shows the distribution grounding switch 40 in the configuration in
which
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Date Recue/Date Received 2021-05-26
power from the mains line 16 passes through ground bar 38 and in which the
power from the
distributed energy resource from the lateral line 30 of the distributed energy
resource passes to
ground. In particular, it can be seen that the pair of contactors 74 and 76 of
the first vacuum
bottle 72 are separated. As a result, current from the first electrical
terminal 60 will not flow
through the contactors 74 and 76 to the first rod 86. Because the contactors
74 and 76 are
separated, power to or from the main 16 will not flow from or to the
distributed energy resource
by the lateral line 30 extending from the second electrical terminal 62. Under
the circumstances
where the first current transformer 54 should detect a fault condition or
detect a signal from the
utility, the first current transformer 54 will transmit a signal to the
magnetic actuator 100 so as to
.. cause the actuator rod 102 to be released from the permanent magnet 104 and
moved to the left.
In particular, the resilient member 106 will urge the actuator rod 102 away
from the permanent
magnet 106. As such, the pin member 108 will pivot at pivot 96 so as to extend
generally
vertically. The hinge member 110 extends linearly. As such, the pin member 108
will urge the
yoke 90 to pivot on pivot point 92 such that the second rod 88 moves upwardly
so as to cause the
contactors 80 and 82 of the second vacuum bottle 78 to close. In this
configuration, power from
the distributed energy resource will flow to ground rod 34. Additionally, the
power from the
mains line 16 will flow to the ground rod 38.
Since the pin member 108 is in a vertical configuration, this will cause the
indicator 112
of display 114 to move so as to indicate (exterior of housing 60) that the
system is "off'. In
.. particular, the pin member 108 acts on a pivot 120 so as to cause the
indicator 112 to move. The
second current transformer 56 will now sense that there is no current flowing
through the
distribution grounding switch 40. As such, this will provide information to
workers that the
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Date Recue/Date Received 2021-05-26
system is in a condition to be worked on. As such, this avoids potential
electrocution.
FIGURE 6 shows a side view of the distribution grounding switch 40 of the
present
invention. In particular, FIGURE 6 shows the configuration of the arrestor 70.
The mechanical
commutation process can take up to twenty milliseconds for either opening or
closing. During
the opening process, the contacts 74 and 76 of the mains vacuum interrupter 40
move apart. At
the beginning of this movement, there is still flow of electricity. When the
current stops flowing,
temporary overvoltages will occur for small periods of time until the
contactors 80 and 82 of the
ground vacuum interrupter 42 close. If the transient overvoltages are too
high, the can cause
damage to the system. The arrestor 70 will limit transient overvoltages during
this time. The
arrestor 70 is connected to the second electrical terminal 62 and supported by
frame 140. The
arrestor 70 extends outwardly of the housing 64.
FIGURE 6 further shows that the magnetic actuator 100 is located within the
interior of
housing 64. The magnetic actuator 100 will have a rod 142 extending therefrom
and outwardly
of the housing. Rod 142 is cooperative with the pin member 108 so as to cause
the movement of
the indicator 112 in the manner described herein previously. Similarly, the
arm 116 is illustrated
as extending outwardly of the housing 64. Arm 116 also has a rod 118 extending
into the housing
64 so as to act upon the pin member 108 in order to move the yoke 90 in the
desired direction.
As such, when a force is applied to the arm 116 exterior of the housing 64,
the user can
selectively move the contactors between their respective positions.
The foregoing disclosure and description of the invention is illustrative and
explanatory
thereof. Various changes in the details of the illustrated construction can be
made within the
scope of the appended claims without departing from the true spirit of the
invention. The
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Date Recue/Date Received 2021-05-26
present invention should only be limited by the following claims and their
legal equivalents.
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Date Recue/Date Received 2021-05-26
