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GEK-1253E
reason the adjustments have been disturbed, the following points should be observed
in restoring them.
Cup Unit (PFD)
1.
The contact gap of this unit is 0.020 inch.
To obtain this gap the following
procedure is recommended.
a.
Advance the right stop screw until the moving contact arm ;s parallel to
the sides of the cup unit.
b.
Advance the stationary contact until it just touches the moving contact.
A neon lamp connected across terminals 9 and 10 is best suited for
identifying the moment of contact.
c.
Tighten the clamping screw so that the stationary contact is secure.
d.
Back the right stop screw off until the measured gap of 0.020 inch exists
between the moving and the stationary contact.
(It should be noted that
0.020 inch corresponds to approximately two-thirds of a turn of the stop
screw. )
e.
Tighten the locknut so as to clamp the stop screw in this position, being
careful not to disturb the contact gap adjustment.
2.* Pickup of the phase-fault detector will operate the auxiliary telephone relay.
The telephone-relay current passing through the holding coil prevents the PFD
contacts from arcing just at pickup.
This holding action also tends to
prevent contact bounce, such as can be detected
if the telephone relay
chatters at higher levels of operating currents.
The holding-coil force is controlled by the air gap between the holding-coil
pole pieces and the armature on the moving assembly and the level of currents
as controlled by the R-l adjustable resistor mounted at the rear of the relay.
The factory setting of the holding-coil force is determined by the dropout
value of the phase-fault detector.
The relays are set to drop out between 50%
and 90% of pickup when the pickup is at the lower end of the adjustable range.
If readjustment is required, do not set R-l less than 80% maximum resistance
in the interest of not exceeding its watt rating.
When the holding-coil adjustment is made, the holding-coil air gap must be at
least 0.015 inch when the PFD contacts are closed and fully wiped in.
3.
The pickup of the cup unit may be changed in the manner described under
SETIINGS.
4.* With the connections of Figure 8A, the clutch should be adjusted to slip at 10
to 12 times minimum pickup current with the unit set at minimum pickup.
The
clutch slipping point may be changed by turning the clutch adjusting screw.
Turning the screw clockwise will cause the clutch to slip at a higher value of
current.
For units with a minimum pickup of 10 amperes or more, tighten the
clutch all the way in.
Be sure to tighten the locking nut, being careful not
to disturb the clutch.
* Revised since last issue
11
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