41-223N
CVQ Relay
6
7.2
ROUTINE MAINTENANCE
All relays should be inspected periodically and the
time of operation should be checked at least once
every year or at such other time intervals as may be
indicated by experience to be suitable to the particu-
lar application.
All contacts should be periodically cleaned. A contact
burnisher style 182A836H01 is recommended for this
purpose.
The use of abrasive material for cleaning
contacts is not recommended
, because of the dan-
ger of embedding small particles in the face of the
soft silver contact 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 have been disturbed. This procedure
should not be used until it is apparent that the relay is
not in proper working order (See “Acceptance
Check”). Electrical checks should be made with the
relay mounted in its case.
8.1
NEGATIVE SEQUENCE VOLTAGE FILTER
A. Apply 120 volts balanced 3 phase voltage 60
hertz to terminals 7, 8, and 9 of the relay, making
sure that phase A, B, and C of the applied voltage
is connected to terminals 7, 8, and 9 respectively.
B. Using a calibrated high resistance voltmeter of
2000 ohms per volt or more, measure the voltage
between the tap on auto-transformer (middle ter-
minal, upper right-hand reactor, front view) and
the tap on the adjustable 2” resistor. If the volt-
age is high (40 to 50 volts) the filter is probably
improperly connected. If properly connected, the
voltage will be low. Using a low range (approxi-
mately 5 volts) move the adjustable tap until the
voltage reads a minimum. This value should be
less than 1.5 volts.
8.2
POLAR UNIT
8.2.1
Contacts
Place a .060 to .070 inch feeler gage between the
right-hand pole face and the armature. This gap
should be measured near the front of the right-hand
pole face. Bring up the backstop screw until it just
makes with the moving contact. Place gage between
contact and the stationary contact on the left-hand
side of the polar unit, and adjust stationary contacts
for 0.046 inches. Bring up the stationary contact until
it just makes with the gage and lock in place. On dou-
ble trip relays, adjust the other set of contact gaps to
close simultaneously.
8.2.2
Minimum Trip Voltage
Short out the adjustable resistor in series with the
polar element. Using the test circuit of Figure 6,
(page 11) adjust the right-hand shunt of the polar unit
so that it toggles over with 3.3
±
0.17 volts on the
voltmeter. Remove short circuit from the resistor and
adjust this resistor so that the polar unit will close its
contacts to the left with 10.4
±
0.52 volts on the volt-
meter. For other sensitivities as indicated in Table 1,
adjust for the voltage shown. Block polar unit con-
tacts closed to the right before proceeding with CV
calibration.
Polar unit flux paths are shown in Figure 7 (page 12)
with balanced air gaps, permanent magnet flux flows
in two paths, one through the front, and one through
the rear gaps. This flux produces north and south
poles, as shown. By turning the left shunt in, some of
the flux is forced through the armature, making it a
north pole. Thus, reducing the left-hand rear gap will
produce a force tending to pull the armature to the
right. Similarly, reducing the right-hand gap will make
the armature a south pole and produce a force tend-
ing to pull the armature to the left.
8.3
CALIBRATION OF POLAR UNIT
If the relay has been dismantled or the calibration
has been disturbed, use the following procedure for
calibration.
With the permanent magnet removed, see that the
moving armature floats in the central area of the air-
gap between the poles of the polar unit frame. If nec-
essary, loosen the core screw in the center rear of
the unit and shift the core and contact assembly until
the armature floats. (This can best be done with the
polar unit removed from the relay.) Then retighten
the core screw and replace the permanent magnet
Table 1:
Volts on
Voltmeter
% of Line
to Neutral
10.4
12.5
14.5
16.6
18.7
20.8
5
6
7
8
9
10
