Setting Calculations - ABB HCB-1 Instruction Leaflet

Type HCB-1 Pilot Wire Relay System
a) Neutralizing reactors may be connected in
series with the pilot to hold pilot-wire poten-
tial close to the remote ground potential in
the presence of a rise in station-ground
potential. They do not limit pilot-wire voltages
to safe values in the presence of a longitudi-
nal induced voltage. When using the neutral-
izing reactor, the pilot-wire sheath should be
insulated from station ground to minimize
sheath-to-pair potential. All other parts in the
cable which are connected to station ground
should also be protected with neutralizing
reactors to minimize pair-to-pair voltages.
b) Drainage reactors may be connected across
the pilot-wire to ground through a KX642 pro-
tector tube. The drainage reactor is particu-
larly effective
voltage in the presence of an induced volt-
age. When the tube flashes, both wires are
connected to ground through the drainage
reactor windings which offer a low imped-
ance to ground but maintain a high imped-
ance to an ac voltage across the wires. Thus,
the HCB-1 system will operate normally even
though the protector tube has flashed over.
The drainage reactor is not intended to han-
dle a rise in ground potential.
c) The neutralizing and drainage reactors may
be utilized together. If the neutralizing reactor
is to be of any value, the drainage reactor
through the protector tube must be con-
nected to remote ground.
For more information with reference to the insulation
and protection equipment, refer to I.L. 41-971.4.
4.6. TRIP CIRCUIT
The main contacts will safely close 30 amperes at
250 volts dc, and the seal-in contacts of the indicat-
ing contactor switch will safely carry this current long
enough to trip a circuit breaker.
The indicating contactor switch has two taps that pro-
vide a pick-up setting of 0.2 or 2 amperes. To change
taps requires connecting the lead located in front of
the tap block to the desired setting by means of a
screw connection.
in limiting pair-to-ground
5.0 SETTINGS
There are four settings in the relay. The correct tap
setting should be determined as outlined under sec-
tion 5.2, "Setting Calculations".
1) Restraint taps – maximum or minimum
To change taps, connect the lead in front of
the relay to the correct tap.
2) T tap – 4, 5, 6, 7, 8, 10, and 12
3) R tap – A, B, C
1
4) R tap – R, G and H
0
5.1. INDICATING CONTACTOR SWITCH (ICS)
The only setting required on the ICS is the selection
of the 0.2 or 2.0 ampere tap setting. This selection is
made by connecting the lead located in front of the
tap block to the desired setting by means of the con-
necting screw.

5.2. SETTING CALCULATIONS

The HCB-1 relay has four sets of taps: R
restraint taps. The following discussion establishes
limits for the various tap settings under different oper-
ating conditions. It should be kept in mind that set-
tings to obtain operation on minimum internal fault
conditions are based on the total fault current that
flows into the protected line from all terminals.
TERMS
A, B, C, D, F, G, H — Relay Taps
I – total minimum internal 3-phase sec-
3P
ondary fault current fed from all termi-
nals, divided by the number of
terminals (2 or 3)
I – maximum secondary load current
L
flowing through the protected line
I – total minimum secondary ground fault
g
current fed into the protected line
from all terminals, divided by the
number of terminals
I (P-P) – nominal
nom
phase fault sensitivity.
I (P-G) – nominal internal line-to-ground
nom
fault sensitivity.
41-971.3M
, T, R , and
1 0
internal phase-to-
9