Note: Descriptions are shown in the official language in which they were submitted.
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BAC.ICGROUI~D_OF THE INV~WTION
The present invention relates to a new and improved
test apparatus for the checking o~ test objects, typi.cally
protective relays, especially voltage, current and/or fre~uency
relays for protecting generators of a power supply network.
This test apparatus comprises a first circuit for
generating and transforming test signals or magnitudes which
are to be delivered to the test object, a second circuit
~or preprogramming the test signals or magnitudes which are
1~ to be delivered to the test objects, a signal and control
device for controlling the course of the test, and a measuring
device for measuring the relay response values.
Test devices of the previously mentioned type, wherein
for testing a relay the test signal or magnitude is supplied to
the primary side of the relay and the test is designated as a
so-called "primary checking" or "primary test" have ~een known
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for qui.e soMe time. Ilowever, these devices p,ossess ,t,he
drawbac]~s that complicated equipment is ne,e~"e,d f~r produ~ing
the test signals or macJnitudes, which may be fgr ins,tance
variable voltages, currents or frequencies, to be delivered to
the test objects. With n~merous protective devices tauyht to
the art by the assignee of this application, potentiometers
haviny movable par-ts are employed for producing variable test
voltages. These potentiometers are prone to disturbance during
operation and are complicated to control. In order -to test
frequency relays there are provi~led complicated means for
measuring the relay frequency. Further, the heretofore known
test devices are collectively complicated and expensive.
SUMMI~RY OF THE INVENTION
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lIence, wi-th the foregoing in mind it is a primar~
object of the present invention to provide a new and improved
constructicn of test apparatus for the checking or testing of
protective relays in a manner no-t associated with the afore-
mentioned drawbacks and limitations of the prior art proposals,
Another and more specific object of the presen~ in-
vention aims at the provision of a test apparatus of the
previously mentioned type whereln it is possible to produce
the test signals or magnitudes, whether s~u,,~ch be voltages,
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currents or frequencies, with the, ,a,id of Eelatiyely s,i,mple
means in an economi,c,al man,ner, and which i~ G~it,,a~lje fo,r, the
manual or automatic testin~ of, both simple a~ well as, ~pmglicated
protective devices,
Now in order to implement these and still further
objects of the invention, which will become more readily apparent
as the description proceeds, thq tes-t apparatus ofthe present
invention is manifested by the features that the first circuit
contains a first test signal generating circuit for supplying
the voltage relay and current relay with yoltage and current
test signals or magnit~udes, respectively, which appear at the
secondary winding of a test transformer with which there is
connected in parallel a static potentiometer. This static
potentiometer comprises a combination of resistors and elec-
tronic switches and delivers to the test objects test signals
or magnitudes in finely stepped values. The first circuit
further comprises a second test signal generatingcircuit ~or
sup'plying the frequency relay with frequency test magnitudes.
. The second circuit comprises a test matrix. The
signal and control device operatively connected with the test
matrix and receivi~g there,,f,rom the information re,~a~ting to the , -
test signals or magnitudes stores a p,redetermined course of
a test program and corres~dingly controls th~ tes,t course.
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'rhe test appar~us of the inv~n~lo~ ~os~es~e~ ~he
~ollowing advantages:
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In order to deliver the test signals or ~agnitudes
to the different test objects there is used a potentiometer
which does not possess any movable parts, thus i9 nok prone to
disturbances and can be controlled more easily. The test
signals or magni-tudes - voltage, current or frequency -- are
delivered to the test object while approximately continuously
increasing or decreasing in steps or increments and upon reaching
the relay response value are displayed and printed-out. A ~-
large number of different protective relays, such as voltage,
current and/or frequency relays, can be checked in succession
in this manner as concerns their response value and their
response time. The decision, whether the reallzed values are
correct or incorrect, is left to the person examining the test
report or results.
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BRIEF DESCRIPTION OF THE DRAWING
The invention will be better understood and objects
other than those set forth above, will become apparent when
consideration is given to the following detailed description
thereof. Such description makes reference to the annexed i~
drawing wherein the single Figure illustrates a circuit
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diagram of an apparatus fox the checkiny o~ protective
devices, typically protective relays.
DETA [ ED DESCRIPTION Ol:' Tl!13 PREFERRED EMBODIME:NTS
Describing now the drawing, the single Figure
illustrates by way of example circuitry of an automatic test
apparatus for the checking of test objects, here in the form
of protec-tive relays 1, 2 and 3, shown by way of example in
the environlnent o~ a pro-tective device for a generator of a
power supply ne-tworkO During operation, the network currents
flow through the protective relays and such have applied thereto
the network or operating voltages delivered by the power plant.
Such a power plant has been schematically indicated in the
drawing by the generator 42, the block transformer 43, the
main current transformers or converters 39 and ~0 and the main
voltage transformer or converter 41. For the sake of simplicity
there have only been shown three relays, a voltage relay 1, . ~
a current relay 2 and a frequency relay 3. However, in .
practice the number of relays which must be checked lS usually
considerablygreater. During the -testing or checking operation,
the relays are supplied in a predetermined sequence with their
appropriate test signals or magnitudes and their response
behaviour is measured, indicated and recorded. ! :
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. A first circuit is provided for generating and con-
~ertlng the test 6ignals or mag~i.tude5 Which are to bé ~el1ve~ed
to the test object, i.e., the relays. This f~rst cirauit
comprises a test transformer 4, 5, 6 having a primary winding 4
connected with an alternat1ng-current voltaye source, schem-
atically represented by the supply terminals 4a and 4b, and
two secondary windings 5 and 6. The first circuit also encom-
passes a ~irs-t test signal generating circuit 5, 11, 8, 37,
38, 7, 9 for supplying the voltage relay 1 and current relay
2 with voltage test sIgnals and current test signals, respectively~,
and a second test signal generating circuit 5, 11, 14 for.supply-
~ing the frequency relay 3 with frequency test signals or
magnitudes.
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The first test signal generatin~ circuit comprises the
first secondary winding 5 of the test transformer 4, 5, 6 and
a so-called static potentiometer 11 connected in parallel with
the secondary winding 5. This potentiometer 11 consists of a
parallel combination of series circuits, each of which is com-
posed of a resistor 12 and series connected electronic switCh
13, typically by way of example a triac. The resistors 12
are dual stepped and can ~e selectively and in combination
connected and disconnected by means of the electronic switches
13, so that there can be adjusted finally stepped resistance
values ~ The static potentiometer 11 can be connected, on the one,
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hand, by means of a switch B wlth one terminal or output 5a
of the secondarywinding 5 with a tap 5b of this secondar~ winding
and, o~ the other hand, by means of a fixed resistor, i.e.,
a potentiometer 8 and by means of the primary winding 7 of a
current transfonner 7, 9 with the other terminal or output 5c
of such s~condary winding 5. The tap 8a of the potentiometer
8 is connected by means of swltch lOa wlth the primary side
input la of the voltage relay 1 and by means of the primary
winding 37 of a voltage-measuring transformer 37~ 38 with ground
potential. The secondary winding 38 of this voltage-measuring
transformer 37, 38 is connected with ground po-ten-tial and by
means of a switch C with a display device 31 and a small printer
32. The secondary winding 9 of the curr:ent transformer 7, 9
is connected with ground poténtia~ and by means of the partial
windings 15 of the primary winding of a phase compensation device
15, 17, 18, 19 and by means of a switeh 10~ with the primary
side-input 2a of the current relay 2. The not particularly
re-~erenced output of the potentiometer 8, connected with the
pri~ary winding 7 of the eurrent trans~ormer 7, 9, is eleetrieally¦
connected with a rest contact of a switch Ao In the illustrated
position of this switeh A this primary winding 7 is short-
eircuited in order to perform a voltage test. In its other
position the switch A short-circuits or shunts the potentiometer
8 during the performance ~ a eurrent test. The potentiometer
11 has assigned to it the task of varying, as re~uired, the
magnitude of the test voltage and the test eurrent, as the case
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may be. The test signals which are deliyered to the r~elays
therefore can be changed ~o as to c,~n,stlt,utema~nitud,~e,s, Whi~h
,e,ither increase or decrease.
The 6econd test signal generating circuit 5, 11, 14
consists of the secondary winding 5 of the test transformer
4, 5, 6, the potentiometer 11 and the voltage-frequency converter I
14 connected in circuit therewith. The o~tput 14a of the voltage-¦ :
frequency converter 14 leads, by means of a switch lOc, to the
primary side input 3a of the frequency r~lay 3. The voltage 1-
which is adjusted by means of the potentiometer 11 is converted
by the voltage-frequency converter 14 into a frequency signal
which is deliv.ered to the frequency relay 3. This test signal, I.
prior to its conversion into a frequency signal, is measured
by means of the voltage-measuring transformer 37, 38 as a '
voltage, so that there is not required any direct frequency
measurement. The secondary winding 6 of the test transformer
4, 5, 6 serves to power the voltage~frequency converter 14.
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The second circuit for pre-programming the test signals
or magnitudes, which are delivered to the test objects, will be
; . seen to comprise a test matrix 33 having five vertical rails 20 1 :
and ten horizontal rails 21 to 30 which'intersect a~ the grid
points. These ve'rtical rails 20 and horizontal rails 21 to 30
are arranged in a matrix ar,ray.- .
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During -testing of the relays the vertical rails 20
receive in succession, for instance by means of a selector switch
S, a voltage si~nal which is further transmitted by means of not
particularly shown plug-in diodes to the horizo~tal rails.
Each of these rails 20 is operatively correlated to a relay
model or a relay type which is to be tested, i.e~, it is
po.ssible by means of such selectorswitch S and by means of such l¦
rails 20 to successivelycontrol for testing purposes a number
of relays of the s~me type or also different types of relays.
The number of vertical rails 20 is dependent upon the number
of relays which are to be tested within a measuriny cycle.
The progra~ming of the rail arrangement or test matrix 33 and
the correlation of the control functions in accordance with the
relay type which is to be tested in eacll instance, is
accomplished by the aforementioned, not particularly illustrated
plug-in diodes which, in each case, connect a vertical rail at
the grid or intersection locations, in accordance with the intended
purpose, with a horizontal rail. Each horizontal rail constitutes
a control output of the second circuit and is associated in
each case with a test signal or control function within the
test operation. Thus, for instance, the rail 21 serves for ¦ -
selectively testing current or voltage, the rail 22 for testing
minimum or undercurrent values, the rail 23 Eor switching to
a second sensitivity range, the rail~24 for frequency testing,
the rail 25 for testing current relàys having inverse character- ¦
istics, the rail 26 for testing the second response stage of
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the relays, the rail 27 for jumpiny relay which is not to
be tested. The rails 28, 29 and 30 serve to control a re-
versing switch 18 for the selection of the phases R, S, T
of the phase compensation device 15, 17, 18, 1~9 which will be
described more ~ully hereinafter. `
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I~, accordingly, the rail 21 for a voltage test is
activated by means of a-plugged-in diode i.e. carries a voltage
signal, then the swltch A is brought into the illustrated position
where the primary winding 7 of the current transformer 7, 9
is short-circuited. To carry out a current test the switch
A is brought into its other position in which it short-circuits
the resistor 8. A control signal from the rail 23 controls
the switch B by means of which the potentiometer 11 is con-
nected with the secondary winding 5 of the test trans~ormer 4,
5, 6. When the rail 23 carries a potential, then the poten- I
tiometer 11 iB connected with the tap of such secondary winding
5.
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Control signals from the rails 22 and 25 control a
first counter 34, which, in turn, controls the static potentio-
meter 11. A signal from the rail 24 controls the voltage-
frequency co~verte~ 14 in that it blocks or activates the same.
The rails 26 and 27 are con~ected with a control device 35 which
thus receives information from the test matrix 33 ~concerning the
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test signals to be supplied. Additionally, the control device
35 stores a predetermined test program course and controls the
course or progress of the test in accordancewith such program.
For this purpose the control device 35 is connected in circuit
with the test objects i.e., the relays 1, 2 and 3 and is
controllably connected with the test contacts lOa, lOb and lOc
o~ these relays 1, 2, and 3.
The counter 34 which is connected with the static
potentiometer 11 opens and closes, respectively, in a
suitable sequence the eight triacs 13 of the dual stepped
static potentiometer 11, so that the total current flowing
through the parallel circuit of the eight triacs 13 increases
in 256 stages from null to its maximum value or decreases from
its maximum value to null. The static potentiometer 11 is
controlled by the coun-ter 34 in a manner such that it delivers
in an approximateiy continuously increasing or decreasing fashion
1, to the relevant relay which is undergoing the test, the
test signals, voltage, current or frequency. The related relay,
at the moment that it responds, blocks the counter 34 at a
count corresponding to the relay response value. A second
counter 36, which is operatively ~onnected with the control
device 35 and receives there~rom start and stop signals, counts
the response time of the relay which is undbrgoing the test.
The relay which is in the progress of being tested. blocks the
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counter 36, at the count corresponding to the response time,
by means ofa stop signal from the control devi~ 35, A
display device 31 which is operatively connected by ,m,~e,ans of ,,
a switch C with the counter 36 and with the voltage-mea~ring
transformer 37, 38 provides a read-out or visual display and
the small printer 32 the automatic print-out of the response
time and the response value, respectively, in successi~n.
The measurement of the test voltages and the measure-
ment of the test currentsconstitute two different problems.
During the testing of voltage relays and frequency relays the
network voltage is turned~off during the test operation, so that
there are effective at these relays the test voltage or the
test f~equency, as the case may be. Both of these test
.~' signals are measured in the form of voltages by means of the
`. voltage transformer 37, 38 and the digital display device 31. 'I
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On the o~her hand, testing of the current relay 2 is
carried out during operation without interrupting the flow of
the network currents, so that this relay has ~lowing there-
through a mixture of the network and test currents. However,
what is measured is not the" test current itself, rather the
sum of the network current and the test current, Phase
differences between these currents are ~mpensated in the
phase compensation device 15, 11, 1~ and.l~. This,compen,~tion
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device comprises first primary w:indinys 15 throuyh which ~10WS
the test current intended for the current relay 2 and delivered
by the current transformer 7, 9, second primary windinys 17
throuyh which flows the network current delivered by the main
current transformer 39 of the power plant, and secondary windings
19 through which flows the phase-compensated test current.
The reversin~ switch 18 controlled by the rails 28, 29, 30
of the test matrix 33 and operatively connected with the indicator¦
device 31 and the small printer 32, selects the appropriate one
~f the phase R,5,T and delivers the phase-compensated test
current to the indicator device 31 and the small printer 32. In
accordance with the test program, the switch C is controlled .
by the con cl device 35.
While there are shown and described present preferred
embodiments of the invention~ it is to be distinctly understood
that the invention is not limited thereto, but may be otherwise
. variously embodied and practiced within the scope of the
iolicwLng aim~.
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