Note: Descriptions are shown in the official language in which they were submitted.
753~6
This invention relates to protector apparatus for
telecommunications lines, and particularly to protector field of
connector blocks for main frames in central offices.
It is a constant requirement that the space required
for the various items of apparatus at central switching offices,
and at other places, be reduced to a minimum. The present invention
provides a protector field which is compact, has a high density of
packing of the individual protectors, and enables use o~ highly
effective protectors.
The protector field mounts a plurality of protectors
which protect the central office equipment, and outside plant equipment,
against line surges and the like, particularly overvoltage and
overcurrent situations. The protector field can be combined with a
test field and a cross-connect field in one unit, called a connector-
protector, the overall dimensions of which are very close to those of
a conventional quick-clip terminal connector block. Thus one central
office frame can optimumly contain connector-protector blocks combined
with cross~connect blocks instead of the protector and test Fields being
mounted on one frame and the cross-connect field on a separate frame.
2Q This saves the eost and space of a frame and associated hardware as
well as operational savings. The test field provides the facility
of testing outside plant cable pairs and the cross-connect field provides
for termination of cross-connect jumper wires from central office
equipment connecting blocks.
The present invention is particularly concerned with
the protector field, The protector field is composed of a metal outer
shell partitioned to accept a plurality of protector units, in columns
and rows. The shell provides a common electrical ground for the
protectors and include detent details at each protector position for a
3~ position detent positioning of the related protector in a partially withdrawn
position. The positioning is such that one way insertion of protectors is
~L~7 ~36~6
ensured.
The invention will be readily understood by the
following description of an embodiment, by way of example, in
conjunction with the accompanying drawings, in which:-
Figure 1 is a perspective view of a protector-
connector block, showing the protector field;
Figure 2 is a front view of the protector
field of the block of Figure l;
Figure 3 is a cross-section on the line III-III
of Figure 2;
Flgure 4 is a longitudinal cross-section
through one form of protector, on the line IV-IV of Figure 5;
; Figure 5 is a cross-section on the line V-V
of Figure 4;
Figure 6 is a longitudinal cross-section similar
to that of Figure 4, through another form of protector;
Figure 7 is a longitudinal cross-section similar -;
: to that of Figure 4, through a further form of protector;
Figure 8 Is a side view of a protector as in
Figure 7;
Figure 9 is on the same sheet as Figures 4, 5
and 6 and is a base plan view of a protector, as in Figures 4,
. 6 or 7;
Figure 10 is on the same sheet as Figure 1 and is
an end view, in the direction of arrow A in Figure 2; of the
cross-connect field;
Figure 11 is a back view in the direction of
arrow B in Figure 10, with a cover partly broken away to show
terminals;
Figure 12 is a further end view, in the direction
of arrow C in Figure 2.
i - 2 -
5i3~i
As illustrated in Figures l, 2 and 3, the
protector field, indicated generally at lO, has a metal case ll
divided into a number of columns by metal dividers l2. The
metal dividers are conveniently spot welded, or brazed, to the
top and bottom end members l3 and 14 by end flanges l5 on the
dividers. The back of the protector field is closed by a
plastic member l6. Inserted into the member l6 are a plurality
of terminals l7. The terminals extend through the plastic
member l6, the forward ends l8 in the present example, being
hollow for the reception of contact pins extending from protectors
and the rearward ends l9, again in the present example, adapted
- for wire wrapping of conductors thereto.
In the particular embodiment illustrated, four
terminals l7 are provided for each protector position,
although differing numbers of terminals can be provided. A
protector position, is defined for four columns by spaced
dividers l2, while a fifth column is defined by a divider 12
and the side wall 2l of the case ll. The dividers have guide
formations 22 formed therein which divide a column into
`, 20 separate positions for protectors. The guide formations 22; also copperate with the shaping oF the protectors, as seen in
Figures 5 and 9, to ensure that the protectors are inserted
~ correctly. In the example illustrated in Figure 2, there are
- five columns of twenty rows, that i5 one hundred protector
positions. Three protectors are indicated in chain dotted outline
at 25 in Figure 2, while two protectors, 26, are shown inserted
in Figure l.
To assist in determination of related terminals,and
to make connection easier, the terminals l7 are of two different
1engths. Thus as seen in Figure 3 the rearward ends 19 of one
,~''
.
, .
- 3 -
753~6
pair of terminals - conveniently the central office wire terminals
- are shorter than the rearward ends of the other pair - which
would be the outside plant wire terminals, for each protector
position.
Formed in the dividers 12 are apertures 30, an
aperture for each protector position. The apertures are positioned
adjacent the outer edges of the dividers 12 and cooperate with
detent means on the protectors 26.
Typical forms of protectors are illustrated in
Figures 4 to 9, and are also described in copending application
serial no. 264,079 filed October 25, 1976.
In the example illustrated in Figures 4 and 5, a
protector indicated generally at 40 comprises a molded plastic
housing 41 having a knob 42 at the closed outer end 43 and a
base 44 attached to the inner end 45. Extending the length of
the housing between closed end 43 and inner end 45 is a metal
ground and retaining bar 46. Ground bar 46 has end webs ext~nding
across the housing, normal to the axis of the housing, as
indicated at 47 and 48, and also a central web 49 extending across
.
the housing midway between the end webs 47 and 48. Four pins
extend through the base, forming two pairs 50 and 50a, 51 and
51a. Pins 50 and 50a are shorter than pins 51 and 51a, and
comprise the connections to the central o~fice. Pins 51 and 51a
connect to the outside plant. One pin of each pair, pins 50a
and 51a in Figure 4, connect to protection devices positioned
between the central web 49 and the end web 47 of the ground bar
46, and the other pair of pins, 50 and 519 connect to protection
devices positioned between the central web 49 and the end web 48
of the ground bar 46. Pins 50a and 51a extend up through the
`! 30 casing but are not shown in full in Figure 4 for clarity.
The protection devices form two sets, each set
4 -
.' '
. . .
~L~7~i3Q~
having a current overload protector and a voltage overload protector.
ln the particular example illustrated, considering first the section
between end web 48 and central web 49, an overcurrent protection
device in the form of a heat coil 55 rests on the end web 48. The
heat coil, comprising a predetermined length of insulated wire, is
wound on a metal bobbin 56 having a central bore in which is soldered
a metal pin 58, the solder having a predetermined melting range. An
; insulating washer 59 is positioned between the bobbin 56 and the web 48,
and the end 60 of the pin is held spaced from the web 48. One end of
the coil 55 is attached to pin 50, via tab 61 and the other end of the
coil is attached to pin 51 via tab 62.
The pin 58 extends from the heat coil 55 and in
the present example carries a carbon ring 63 which rests on a
flange 64 on the pin 58. A ceramic tube 65 rests on the carbon ring 63
and holds a carbon rod 66. A small gap 67 is provided between the
opposed ends of the carbon ring 63 and the carbon rod 66. On the
end of the carbon rod 66 remote from the carbon ring 63 is positioned
a metal cap 68 and a compression spring 69 extends between the cap 68
and the central web 49.
- 20 A similar arrangement exists between end web 47 and
central web 49 and the same references are applied to the same details,
with the suffix "a" thereafter.
The operation is as follows: With a normal line current
and voltage, there is a direct connection between pin 51 (51a) and
pin 50 (50a) via the heat coil 55 (55a). With normal current and voltage
no undue heating of the coil occurs. However, on occurrence of an
overcurrent condition, on one or other or both lines, heating of the
related heat coil 55 (55a) occurs. Melting o-F the soldered joint between
bobbin 56 (56a) and pin 58 (58a) results and the pin 58 (58a) is pushed
by the spring 69 (69a~ via carbon rod 66 (66a), ceramic tube 65 (65a)
and carbon ring 63 (63a). The end 60 (60a) of the pin contacts
-- 5 --
., i .
'1~7536;~;
the related end web 48 or 47 of the ground bar 46. There is thus
provided a direct path from pin 51 (51a) to ground via the metal
bobbin 56 (56a) and the pin 58 (58a). The ground bar 46 is electrically
connected to an electrical ground by means of a ground spring 70 attached
to the ground bar 46.
For an overvoltage condition, on one or the other line,
or both lines, arcing occurs across the related gap, or gaps 67 (67a).
In this case there is thus provided a path from pin 51 (51a) via metal
pin 58 (58a), carbon ring 63 (63a), gap 67 (67a), carbon rod 66 (66a),
end cap 68 (68a) and spring 69 (69a) to the central web 49 and thus
to the ground bar 46 and ground spring 70. A short term overvoltage
will merely result in the arcing across the gap 67 (67a) for the
time of the overvoltage, for example during a voltage surge. However
if an overvoltage occurs for an extended period heat from the carbon
assembly will be transferred to the pin 58, melting the solder joint
between the metal bobbin and the pin, with resultant release of the
metal pin 58 (58a).
It is often desired that partial disconnection is
required. For example if a particular pair of lines is to be
disconnected from the central office to remove service from a
terminal for example, disconnection from the central office is effected
but protection of the outside plant lines is still required. This is
obtained, conventionally, by partial withdrawal of the protector. One
pair of pins - the outside plant pins - are usually larger than the other
pair. This is seen in Figure 4 where the pins 51 (51a) are the outside
plant pins and are larger than the central office pins 50 (50a).
In many instances this partial withdrawal is not
positive, in that the protector can be withdrawn too far - with
no protection for the outside plant lines, or not withdrawn far
enough, leaving the particular terminal still connected. Further,
in the confined space in a connector unit, a partially withdrawn
. . .
-- 6 --
~753~
protector can easily be knocked, the protector then being pushed
in, or falling out.
The protector of the present invention is provided
with a detent member which locates positively with a hole in the
connector unit. A flexible elongated member 80 is positioned on
one side of the protector at the outer end. In the particular
example illustrated in Figure ~ the inner end 81 of the member
80 fits in a groove or slot 82 formed in the housing 41.
~ Similarly the outer end 83 of the member 80 fits in a further
; 10 groove or slot 84 in the knob 42. There is a clearance space
85 between the main portion of the member 80 and the adjacent
wall portion 86 of the housing 41. At a mid portion of the
member 80 are two outwardly extending ribs 87 and 88 spaced a
short distance apart. In the particular example the opposed
faces 89 of the ribs are substantially normal to the axis
of the member 80 while the outer faces 90 and 91 are inclined,
giving the ribs 87 and 88 a somewhat wedgeshaped cross-section.
The protector is inserted in a protector section
; of a connector unit or block. A particular example is one
descrlbed and illustrated in copending application serial
number 264,036, filed October 25, 1976.
Conveniently the protector section is of metal sheet positioned
to provlde a plurality of tubular receptacles in each of which a
protector can be lnserted. As the protector section is of metal
the grounding springs 70 can be in direct contact with the metal
protector section which in turn is connected to a ground
connection. However it is possible to provide alternative
grounding means in the protector sec~ion such as if the protector
- section is of a non-conducting material, or for other reasons.
In one wall of each opening, suitable holes are
formed through which the ribs 87 and 88 can project. On
,,.
-- 7 --
."
3C3 ~;
initial entry of a protector into a receptacle the protector is
pushed and the long pins 51 (51a), enter related sockets. At
this time and position the member 50 is deflected to enable the
innermost rib 88 to enter the receptacle and then spring out
with the rib 88 in a first hole. This deflection is assisted by
the inclined surface 91. To fully insert the protector the
member 80 is depressed, rPleasing the rib 88 and the protector
pushed in fully. The shorter pins 50 enter related sockets and
the ribs 87 and 8)3 each enter a hole in the wall of the
receptacle, rib 87 being in the hole into which rib 58
previously fitted.
To partially withdraw a protector it is only
necessary to pull on the knob 42. The inclined sur-face 90 of
rib 87 deflects member 80 inwards and the ribs 87 and 88 move
out of the related holes. As soon as rib 88 is opposite the
outer hole the member 80 springs outward and rib 88 enters
the hole. Further outward movement is prevented by the face 89
on the rib 88 which acts as an abutment. Accidental movement
in either direction is prevented by the faces ~9. For complete
withdrawal of a protector it is necessary to press the member 80
inwards to disengage the rib 88 from the hole. There is thus a
positive location for partial withdrawal. The protector cannot
be accidently withdrawn completely, and once partially with-
drawn is held securely in that condition against accidental
reinsertion or complete withdrawal.
Figures 6 and 7 illustrate alternate forms of
protector and detent members. Figure 6 is very similar to Figure 4
and only the interior of the protector is shown,the housing omitted.
The major difference in Figure 6 is that instead of the heat coils
55,(55a),being at opposite ends,with the overvoltage protection
devices between them on either side o~ the central web 49, the
, .
-- 8 --
~6~17~3~G
arrangement in each section of the protector is the same. Thus
heat coil 55 rests on the inner web 48, insulated therefrom by
the insulating washer 59, and metal pin 58, carbon ring 63,
ceramic tube 65, carbon rod 66, end cap 68 and spring 69
extending between the heat coil and the central web 49. However
-For the outer section, heat coil 55a rests on the central web,
insulated therefrom by the washer 59a, and the pin 58a, carbon
ring 63a, ceramic tube 65a, carbon rod 66a, end cap 68a and
spring 69a extend in that order between the heat coil and the
outer end web 47. Also, the central web is shown as a separate
- member attached to the main portion of the ground and retaining
bar 46, although this is shown only to illustrate an alternative
form of construction.
Figure 7 illustrates an alternative form of
ground spring 70. Ground bar 46 is as in Figure 4 with an
integral central wPb 49 extending normal to the main portion.
Also the positions of heat coils 55, (55a), and the overvoltage
devices are reversed as compared with Figure 4, and a different
form of detent is illustrated.
The ground bar 46 contains all the components.
All the loadings, for example by the springs 69, are carried by
the ground bar and are not transmitted to the plastic casing.
This is particularly desirable in overheating situations, as due
to overloads, as the ground bar will not distort readily, whereas
the plastic casing will melt or soften.
The detent 95 is formed integral with the housing
41 and is cantilevered therefrom. Thus, as illustrated in
Figure 7, the detent is molded as part of the housing 41 being
hingedly attached at its inner end 96 and extending outwards to
end approximately at the level of the knob 42. In this instance
the outer end 97 of the detent is free of the housing. Similar
.~
- 9
~L~7~3~6
ribs 87 and 88 are formed on the detent 95 as in the form illustrated
in Figure 4 and the action for locating the protector in the partially
withdrawn and fully inserted condi~ions is the same.
Figure 8 is a side view of the form of protector
illustrated in Figure 7, particularly showing the detent 95 and
the ground spring contact 70. Figure 9 is a plan view of a base of a
protector, showing the pin positioning and is typical of the arrangement
for all forms of protector. Also seen is the shaping of the protector -
at 100 - for cooperation with the formations 22.
The ground spring 70 extends for substantially the full
length of the ground bar 46, having two arcuate portions 70a extending
through apertures in the protector housing. This gives improved heat
conductance to the protector section of the connector unit. The spring
is spot welded to the ground bar 46 at 105, but may be attached by other
means.
As previously stated, the protector field is used in
combinations with a test field and a cross-connect field to provide a
combination unit. However, if desired, perhaps to replace existing
protector field units with units suitable for the novel form of
2Q protectors as illustrated in Figures 4 to 9, and as described and
illustrated in the above-mentioned application Serial No.
it is possible to make and provide protector field units on their own,
without test field and cross-connect field features, or with only one
of such ~eatures, for example with a cross-connect field only. Also,
other types of units, not described, such as special service, denied
service, reverse cable and other, can be incorporated in a similar
protector unit housing to mount in the protector field. A protector field
unit as described above in relation to Figures 1, 2 and 3 provides certain
advantages over conventional units.
Figures 10 to 12 illustrate a combination unit including
the protector field of Figures 1, 2 and 3 and a test field - indicated
..'
- 1 0 -
-- ~63 7~3~6
generally at 100 - and cross-connect field - indicated generally at
101. These also appear in Figures 1, 2 and 3.
The test field 100, as seen in plan view, is angled
complimentary to the protector field, and the cross-connect field 101
is at one side of the combination unit extending at right angles to
the protector Field. The test field is also angled complimentary to
the cross-connect field, being positioned at a junction between the
protector field and the cross-connect ~ield.
The test field provides test point access to all the
outslde plant cable pairs and is wired ;n parallel with the cable
palrs. It comprises a molded plastic block 110 containing, in the
present example, two hundred recessed test contacts 111 at the front
and the same number of wire wrap terminals 112 at the rear~ each
related contacts 111 and terminal 112 forming a unitary member which
can be molded in or pressed in the block 110. The contacts, and
terminals, are arranged in forty horizontal rows (twenty pairs)
of five contacts per row. Two contacts 111, and their related
` terminals 112, are provided for each protector position in the
;~ protector field. Also each pair of contacts 111, and related
termlnals 112 are directly related to cooperative terminals in
the cross connect ~ield. Typical wiring of the various fields
will be described later in relation to Figure 3. A test probe
can be inserted into any of the contacts 111 to test continuity of
the outside plant lines. Individual or bulk testing can be done,
wlth the appropriate equipment.
The cross-connect field 101 comprises a molded plastic
terminal block 115 in which are positioned two hundred insulating
slicing terminals 116. The terminals in the present example are of
the form as in patent no. 846,965 dated July 14, 1970 and have
three beams providing two channels or slots for wires~ The
terminals are arranged in rows of five terminals each~
53~
The block 115 is pivotted at one side by pivots 117,
the top one of which is seen in Figure 1. The block is held closed by
screws 118 which screw into the block 110 of the test -field. When the
cross-connect field is opened, access is available to the rear ends 119
of the terminals 116 which are adapted for wire wrapping. Each terminal
has perceptual movement in the block 115 for ease of wire tracing. A
fanning strip 120 (Figure 11) extends along the side at which the
block 115 pivots, and has twenty slots. Each slot has a constricted
opening and the wires must be forced slightly through the opening to
enter the slot and thus be positively retained.
A cover 125 is attached to the rear of the protector
field, by screws 126. Removal of the cover provides access to the
rear ends 19 of the terminals 17 in the protector field. At the side
of the complete unit remote from the cross-connect field, a web 127
extending from the side of the protector field casing provides a mounting
for a cable end 128. Apertures 129 permit passage of conductors from
the cable into the rear of the protector field for connection to the
rear ends 19 of the terminals 17.
A further fanning strip 130 is positioned at the rear
i~ 20 of the protector field, extending down one side and adjacent to the
web 127. This fanning strip also has twenty apertures or slots 131
with constricted openings and serves to hold jumper wires from the
terminals 116 in the cross-connect field.
A typical wiring pattern or circuit is diagrammatically
illustrated in Figure 3. It should be appreciated that wires are in
pairs and in Figure 3 the wires of a pair are vertically spaced so that,
in looking down, as in Figure 3, only one wire of a pair is seen.d
Starting from the cable end or stub 128, a pair of wires 135,
outside plant wires, passes through an aperture 129 and is connected,
as by wire wrapping, to the rear ends 19 of two terminals 17 of one
protector position. The particular terminals are the longer of the two
- 12 -
3L~753~6
pairs for the protector position and are the terminals to which the
outside plant pins of the protector connect. The circuit is then
through the protector to the other pair of terminals 17 at that protector
position. From these terminals wires 136 run to the rear ends 119 of
a pair of terminals 116 in the cross-connect field 101. From the front
ends of these terminals jumper wires 137 for connection to the central
office equipment. A further pair oF wires 138 runs from the rear ends 19
of the terminals 179 to which are connected the wires 135, to two of
the terminals 11~ in the test field 100. This connects the two related
contacts 111 to the outside plant wires 135.
In position in a frame, the cross-connect field 101 usually
faces forward when a composite connector block is provided. When a
protector field only is provided, the protector field is mounted to
provide easy access to both front and rear.
;
.
"
. .
"
~ - 13 -
