41-251.21C
5
Type CRN-1
Reverse Power Relay
every year or at such other time intervals as may be
dictated by experience to be suitable to the particular
application. Phantom loads should not be used in
testing induction-type relays because of the resulting
distorted current wave form which produces an error
in timing.
All contacts should be periodically cleaned. A contact
burnisher Style #182A836H01 is recommended for
this purpose. The use of abrasive material for clean-
ing contacts is not recommended, because of the
danger of embedding small particles in the face of
the soft silver and thus impairing the contact.
6.3
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 unless it is apparent that the relay
is not in proper working order. (See Section 6.1,
“ACCEPTANCE CHECK”.)
6.3.1
Timer Unit (T)
a.
Contact
By turning the time dial, move the moving con-
tacts 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 should coincide with the “0”
mark on the time dial.
For relays identified with a “T”, located at lower
left of stationary contact block, the index mark on
the movement frame will coincide with the “0”
mark 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 vari-
ous time dial positions in line with the index mark
will give operating times as shown on the respec-
tive time-voltage curves.
6.4
MINIMUM OPERATE VOLTAGE
The adjustment of the spring tension is required in
setting the minimum operate voltage of the relay. A
spring shield covers the reset spring of the CV unit.
To remove the spring shield, requires that the damp-
ing magnet be removed first. The screw connection
holding the lead to the moving contact should be
removed next. The second screw holding the moving
contact assembly should then be loosened not
removed.
(CAUTION: this screw terminates into a
nut held captive beneath the molded block. If
screw is removed, difficulty will be experienced
in the reassembly of the moving contact assem-
bly.)
Slide the spring shield outward and remove
from relay. Tighten the screw holding the moving
contact assembly to the molded block. Close the
directional contacts.
With the time dial set on “0”, wind up the spiral spring
by means of the spring adjuster until approximately 6
3/4 convolutions show.
Set the relay dial to position 6.
Adjust the control spring tension so that the moving
contact will leave the backstop at 65 volts +1.0% and
will return to the backstop at 65 volts -1.0%. This
value is for the 120 volt relay. Proportional voltage
apply for the 208 and 240 volt relay. Replace the
spring shield.
6.5
TIME CURVE CALIBRATION
Install the permanent magnet.
Set the time dial to position #11. Apply rated voltage
to terminals 6 and 7 with the directional contacts
closed. Adjust the permanent magnet keeper until
the operating time is 40 seconds
±
3%.
6.6
INDICATING CONTACTOR SWITCH-UNIT
Close the main relay contact and pass sufficient dc
current through the trip circuit to close the contacts of
the ICS. This value of current should not be greater
than the particular ICS nameplate rating. The indica-
tor target should drop freely.
Repeat above except pass 85% of ICS nameplate
rating current. Contacts should not pickup and target
should not drop.
