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FAULT
DETECTOR
RELAY
CHC12A, CHC13A AND CHC138
INTRODUCTION
This supplement in conjunction with GEK-1253
forms instructions for the CHC12A relay. All in-
formation pertinent to the CHC12A relay but not
covered by this supplement isasshowninGEK-1253.
The CHC l2A relay is a three-phase high speed
nondirectional overcurrent relay.
The relay con-
sists of an induction cup unit (PFD), a target unit,
and a telephone-type seal-in unit mounted in an S-2
size drawout case.
The CHC13A is similar to the CHC12A except
for the contact circuit arrangement.
The CHC13A
(PFD) operates an auxiliary telephone relay which
provides two normally open electrically separate
contacts.
A target is wired in one of these contact
circuits.
This auxiliary relay occupies the same
position as the seal-in unit in the CHCI2A.
The
auxiliary relay is a D.C. continuously rated unit
that draws less than 5 watts.
The CHC l3B is similar to the CHC 13A except
for internal connection.
The main operating unit of this relay is similar
in construction except for the moving element stop
screw, and has the same operating characteristics,
as the PFD unit of the CHCllA relay described in
the attached GEH-2035.
APPLICA TION
The CHC 12 relay is designed for use as a cur-
rent fault detector in connection with distance relays,
to prevent operation of the associated timer, or
tripping of the circuit breaker due to loss of relay
potential supply for other reasons than a system
fault.
This can occur due to (1) short circuits or
open circuits involving the potential supply, or (2)
due to switching (with some configurations of power
circuits), or (3) due to the use of line-side potential
supply.
In the latter case, the fault detector pro-
tects the timer against burnout, and prevents false
re-tripping of the circuit breaker at the instant of
reclosure.
The case size and internal connections are
arranged to provide mechanical and electrical inter-
changeability with the PJC31C or D. The advantage
of the CHC over the PJC is that it is designed to
permit operation in the picked up position, so that
it can be used where the maximum load current
exceeds the mlnlmUm fault current.
During load
conditions which pick up the CHC, it cannot perform
function (1) above, and
it
mayor may not perform
function (2) above (depending on whether the con-
nections are such as to pick up the CHC), but it
will always perform function (3).
The relay includes a separate target and seal-in
unit operated from trip current.
The target and seal-in units ratings are given
below:
,
I ,
Rated
Operating
Trip Duty
Resistance
I
I
Current
Range
AMPS
OHMS
- -
0.2
0.2 -
3
3
12.4
1.0
1 - 30
30
0.64
, . -
2.0
2 - 30
30
0.22
---~-~-
--
Typical external connections for both CHC12A
and CHC13A are shown in Figs. 2 and 7 of this
supplement.
CONSTRUCTION
Outline and Panel Drilling dimensions for the
Type CHCI2A, CHC13A and 13B relays are shown
in Fig. 8 of this supplement.
The internal connections for these relays are
shown in Figs. 3, 4 and 5 of this supplement.
RECALmRA TION
The moving contact stop screw assembly of
this relay is on the left rear section of the moulded
head directly behind the stationary contact.
The contact gap of the PFD is 0.020 inch. This
gap is set at the factory and
it
normally will not be
necessary to reset it.
However,
if
an inspection
indicates that this setting has been disturbed the
following procedure is recommended.
a. Remove the rear ball stop assembly.
b. Loosen the locking screw of the contact
stop screw assembly and advance the stop
screw until the moving contact arm is
parallel to the sides of the cup unit.
These instructions do not purport to cover all details or variations in equipment nor to provide for
every possible contingency to be met in connection with installation,
operation or maintenance.
Should
further information be desired or should particular probleTf15 arise which are not covered sufficiently for
the purchaser's purposes, the matter should be referred to the General Electric Company.
Tu the extent r"<1uirAd the prod'.1cts described herein meet applicabh'
"1NSr,
IEEE and NEMA standards;
but
no
s,]ch
,iSSUrancc)
js
given h'ith respect
to
local codes and
ordindnce~-;
b::.ca!l~;c
i'hey vaz'y greatly.
I
I
3
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