ABB CWC, Instruction Leaflet

41-242.2F

Type CWC and CWP Directional Ground Relay

6

4.0

SETTING

4.1

CWC INDUCTION UNIT

Select the desired upper and lower pole taps. Set the
time dial by applying a preselected current to the
relay coils, and adjusting the dial position to obtain
the desired time of operation. Alternatively the dial
may be set by inspection, if the timing coordination is
not critical.

4.2

CWP INDUCTION UNIT

Select the desired upper pole tap. Set the dial posi-
tion by applying a preselected voltage and current
(current lagging voltage by 60 ° - see Fig. 16 to the
relay coils and adjusting the dial position to obtained
the desired time of operation. Alternatively the dial
may be set by inspection, if the timing coordination is
not critical.

4.3

INDICATING CONTACTOR SWITCH (ICS)

No setting is required on the ICS unit except 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 connecting screw. When the relay energizes a
125 or 250 volt d-c type WL relay switch, or equiva-
lent, use the 0.2 ampere tap; for 48 volt d-c applica-
tions set relay in 2 tap and use S#304C209GO1
Type WL Relay or equivalent.

4.4

INDICATING INSTANTANEOUS TRIP (IIT)

Since the minimum and maximum markings on the
scale only indicate the working range of the core
screw, the core screw must be adjusted to the value
of the pickup current desired.

The nameplate data will furnish the actual current
range that may be obtained from the ITT unit.

5.0

SETTING CALCULATIONS

The following information is required to set these
relays:

1. The maximum and minimum ground fault current
for faults at the relay and at the remote bus. These
values should be residual current which is three
times the zero sequence current.

2. The maximum and minimum polarizing current or
voltage values for the faults above. The values
should be residual currents or voltage which are
three times the zero sequence values.

3. The current transformer ratios of the main and
polarizing current transformers for the type CWC
relay applications or the main current transformer
ratio and the polarizing potential transformer ratio for
the type CWP relay application.

Each relay should be set to operate as rapidly as