Routine Maintenance - ABB CWC Instruction Leaflet

Type CWC and CWP Directional Ground Relay
The core screw which is adjustable from the top of
the trip unit determines the pickup value. The trip unit
has a nominal ratio of adjustment of 1 to 4 and an
accuracy within the limits of 10%.
The making of the contacts and target indication
should occur at approximately the same instant.
Position the stationary contact for a minimum of 1/32"
wipe. The bridging moving contact should touch both
stationary contacts simultaneously.
Apply sufficient current to operate the IIT. The opera-
tion indicator target should drop freely.
5. Indicating Contactor Switch (ICS)
Close the main relay contacts and pass sufficient d-c
current through the trip circuit to close the contacts of
the ICS. This value of current should not be greater
than the particular ICS tap setting being used. The
operation indicator target should drop freely. The
contact gap should be approximately 0.47" between
the bridging moving contact and the adjustable sta-
tionary contacts. The bridging moving contact should
touch both stationary contacts simultaneously.
7.2

ROUTINE MAINTENANCE

All relays should be inspected and checked periodi-
cally to assure proper operation.
All contacts should be periodically cleaned. A contact
burnisher S#182A836H01 is recommended for this
purpose. The use of abrasive material for cleaning
contacts is not recommended, because of the danger
of embedding small particles in the face of the soft
silver and thus impairing the contact.
8.0 CALIBRATION
Use the following procedure for calibrating the relay if
the relay has been taken apart for repairs or the
adjustments disturbed. This procedure should not be
used until it is apparent that the relay is not in proper
working order. (See "Acceptance Check").
1. Contact
By turning the time dial, move the moving contacts
until they deflect the stationary contact to a position
where the stationary contact is resting against its
backstop. The index mark located on the movement
frame will coincide with the "O" mask on the time dial
when the stationary contact has moved through
approximately one-half of its normal deflection.
Therefore, with the stationary contact resting against
the backstop, the index mark is offset to the right of
the "O" mark by approximately .020". The placement
of the various time dial positions in line with the index
mark will give operating times as shown on the
respective time-current curves. For double trip
relays, the follow on the stationary contacts should
be approximately 1/32".
2. Minimum Trip Current
Type CWC Relay - Connect the upper and lower pole
coils in series and pass current in polarity on both
coils. With one tap screw in the 1 multiplier position
and the other screw in the .25 product tap for the .25-
4 product range or the 2.25 product tap for the 2.25 -
36 product range, apply current and adjust the spring
tension so that the contacts just close at tap value
product.
Type CWP Relay - Connect the relay per Fig. 16. Set
in the lowest tap, apply 100 volts across terminals 6
and 7, and apply minimum pickup current, leading
the voltage by 300 °, (0.20 amperes for the 20-150
range, 0.75 amperes for the 75-600 range.) Then,
adjust the spring tension so that the contacts just
close.
3. Time Curve Calibration
Type CWC relay - Set the time dial to position 6 and
the product tap to .25 or 2.25. Set the multiplier tap to
1. Connect the upper and lower pole coils in series
and pass a current equal to 4 x v tap product in polar-
ity thru the coils. Adjust the permanent magnet
keeper until the operating time is between .95 and
1.01 seconds. Other points on the time curve of Fig-
ure 9 should be within ± 7% of the values shown.
(The multiples of tap product shown in Figure 9 equal
the square of the current passed thru the coils
divided by the tap product.)
Type CWP Relay - Connect the relay per the test cir-
cuit of Fig. 16. Set the 6 time dial and the lowest tap.
Apply 100 volts to potential coil and 10 times tap cur-
rent. (Current leading voltage by 300°). relay operate
between 1.43 and 1.51 seconds. Other points of the
time curve should be within ±7% of the value shown
on Fig. 11.
4. Indicating Contactor Switch (ICS)
Close the main relay contacts and pass sufficient d-c
current through the trip circuit to close the contacts of
the ICS. This value of current should not be greater
than the particular ICS tap setting being used. The
operation indicator target should drop freely.
41-242.2F
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