break contacts, and when closer settings are
desired they should be made by test.
ADJUSTMENTS AND MAINTENANCE
The proper adjustments to insure correct
operation of this relay have been made at the fac-
tory and should not be disturbed after receipt by
the customer. Contact or pickup settings must be
made as required by the application, but alteration
of assembly adjustments should be avoided. If the
adjustments have been changed, if the relay has
been taken apart for repairs, or if it is desired to
check the adjustments at regular maintenance
periods, instructions below should be followed.
All contacts should be cleaned periodically. A
contact burnisher S#182A836HOl is recommend-
ed 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 con-
tact.
INSTANTANEOUS UNIT
Remove the plunger core and see that the top
of the plunger is clean. Reassemble the plunger,
and adjust the position of the core screw so that
when the contacts are closed the plunger butts
against the stop with the spring half compressed.
With a l/32 inch contact separation, the contacts
should pick-up at 6 amperes, 60 cycles. If the
plunger does not pickup and seal in at this current,
adjust the core screw so that it will and yet have
sufficient compression of the spring to prevent
sticking. Test for sticking after 50 amperes has
been passed through the coil.
OPERATION INDICATOR
Adjust the indicator to operate at 1.0 ampere
direct current gradually applied by loosening the
two screws on the under side of the assembly, and
moving the bracket forward or backward. If the
two helical springs which reset the armature are
replaced by new springs they should be weakened
slightly by stretching to obtain
calibration. The coil resistance is
0.16 ohm.
the 1 ampere
approximately
1 6
CONTACTOR SWITCH
Adjust the stationary core of the switch for a
clearance between the stationary core and the
moving core of l/64” when the switch is picked
up. This can be done by turning the relay up-side-
down or by disconnecting the switch and turning it
up-side-down. Then screw up the core screw until
the moving core starts rotating. Now, back off the
core screw until the moving core stops rotating.
This indicates the points where the play in the
assembly is taken up, and where the moving core
just separates from the stationary core screw. Back
off the core screw approximately one turn and lock
in place. This prevents the moving core from strik-
ing and sticking to the stationary core because of
residual magnetism. Adjust the contact clearance
for 3/32” by means of the two small nuts on either
side
of the the Micarta disc. The switch should
pick up at 2 ampere dc. Test for sticking after 30
amperes have been passed through the coil.
HEATER UNIT
The assembly and adjustment of the thermal
unit requires alignment fixtures and other special
tools, as well as special test equipment for locating
the position of the compensating spring assembly
on the shaft and determining the calibration
points. Any dismantling or alteration of the ad-
justments should be avoided, as this may result in
excessive bearing friction or calibration errors.
However, the construction and overload capacity
of the thermal unit is such that very little
maintenance should be required.
The resistance of the heater and instantaneous
unit, measured at the case terminals, should be
0.25 ohm when the shorting link is open and 0.13
ohm when the link is closed.
The moving contact should rotate without
noticeable friction, and when displaced manually
and released it should return to its original posi-
tion. The shaft should have about 0.010 inch end
play.
If the calibration of the thermal unit is to be
checked at one or more points, the precautions
mentioned in previous sections should be observed.
Testing should be done with the relay in its case