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41-971.3M
The nominal 3-phase fault pick-up current from equa-
tion 7 is:
I
=
2T
=
8 amperes
nom
5.3.2. Ground Fault Pickup
Set R
= H
0
For line to ground fault:
400
+
285
5
×
I
=
----------------------- -
-------- -
=
g
2
600
×
×
I
=
2 0.12 4
=
0.96A
nom
5.3.3. Restraint Tap
Use maximum restraint tap.
6.0 INSTALLATION
The relays should be mounted on switchboard pan-
els or their equivalent in a location free from dirt,
moisture, excessive vibration, and heat. Mount the
relay vertically by means of the four mounting holes
on the flange for semi-flush mounting, or by means of
the rear mounting stud or studs for projection mount-
ing. Either a mounting stud or the mounting screws
may be utilized for grounding the relay. The electrical
connections may be made directly to the terminals by
means of screws for steel panel mounting or to the
terminal studs furnished with the relay for thick panel
mounting. The terminals stud may be easily removed
or inserted by locking two nuts on the stud and then
turning the proper nut with a wrench.
For detailed flexitest case information, refer to I.L.
41-076.
7.0 ACCEPTANCE TESTS
The following tests are recommended when the relay
is received from the factory.
HCB-1 current pickup values will be within 5% toler-
ance of the I.L. specification, only for those taps at
which the relay is calibrated. For other tap settings,
the tolerance may be higher than 5% of nominal,
unless recalibration of the relay is performed.
12
2.85A
Type HCB-1 Pilot Wire Relay System
The HCB-1 is factory calibrated at the following taps:
R
: "C" Tap
1
R
: "H" Tap
0
T
"4" Amps
If other tap settings are used, the HCB-1 relay must
be recalibrated at the applied settings to obtain
pickup current within 5% of the I.L. specifications.
7.1. MAIN UNIT
Connect the relay to the insulating transformer as
shown in Figure 8, and set C, H, 4 and maximum
restraint tap. With the insulating transformer termi-
nals H1 and H4 open circuited, measure the mini-
mum pick-up current I79 (min.), with current applied
through terminals 7 and 9. This value should not be
greater than 2.25 amperes.
NOTE: The relay may operate at values of cur-
rent lower than 2.25 amperes depending
upon the insulating transformer used and
the prior history of the polar unit. The
pickup should not be lower than 1.4
amperes. To increase pickup, short H1-H4
of
insulating
amperes momentarily to terminals 3 and
5 of relay and check pickup of relay. It
should be 2.12 + 5% amperes. If not, the
polar unit should be recalibrated per
"Polar Unit Calibration."
Now, connect a resistance, R
of the insulating transformer, with a 10-mfd capacitor
connected between H2 and H3. Connect a capacitor.
CPW in parallel with R
PW
specified in Table 5 suddenly apply I35 = 30 amperes
(through terminals 3 and 5).
Table 5
RPW TEST - Maximum Restraint Tap
R1 = C, R0 = H, T-4
Insulating
Transformer
Ratio
In Ohms
4 to 1
1200
6 to 1
2700
transformer,
apply
, across H1 and H4
PW
. With R
and C
set as
PW
PW
C
PW
*
R
in
PW
Microfarads
1900
0.75
4300
0.33
40
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