T I Me Overcurrent Un I T - GE IFC66A Instructions Manual

TIME OVERCURR ENT U N I T
If it is found during instal l ation or periodic testing that the time overcurre nt unit is out of l imits,
the unit may be recal ibrated as fo l l ows:
Pickup Tests
Rotate time dial to No. 0 time -dia l setting and check by means of a l amp that the contacts just cl ose.
The point at which the contacts _Jst cl ose can be adjusted by running the stationary contact brush in
or out by means of its adjusting screw.
With the contacts just c l osing at No. 0 time setting, there shou l d be sufficient gap between the
stationary contact brush and its meta l backing strip to insure approximate l y 1 / 3 2 inch wipe.
The pickup of the unit for any current tap setting is adjusted by means of a spring-adjusting ring.
By turning the ring the operating current of the unit may be brought into agreement with the tap setting
emp l oyed if for some reason, this adjustment has been disturbed.
setting intermediate between the various tap settings to be obtained.
recommended that the higher tap setting be used.
agree with the time current characteristics of Figures 6 and 7, if the re l ay has been adjusted to pickup
at a va l ue other than tap va l ue, because the torque l eve l of the re l ay has been changed.
C onnect the operating coil terminal s to a source of the proper frequency and good waveform having a
vo l tage of 1 1 0 or more, with resistance l oad boxes for setting the current.
With the tap b l ock set for the l owest tap and the time dial set where contacts are just open, adjust the
contro l spring to just c l ose the contacts within the l imits given bel ow which are p l us and minus 1 percent
of the tao amps. See Tab l e 1 3 .
Tap Range
0 . 5- 4
l . 0 - 1 2. 0
It shoul d never be necessary to wind up the control spring adjuster more than 3 0 degrees (one notch ) or
unwind it more than 1 20 degrees (three notches ) from the factory setting to obtain the above pickup setting.
Time Tests
With the tap b l ock set for the l owest tap and the time dia l at No. 5 setting, appl y five times tap
current to the re l ay.
Adjust the position of the drag magnet assemb l y to obtain an operating time as l isted in Tab l e 1 4.
However, it wou l d be preferab l e to adjust the operating time as near as possib l e to 1 8. 6 seconds.
drag magnet assemb l y shou l d be approximate l y in the m idd l e of its trave l .
adjusted by l oosening the two screws securing it to the support structure.
rr·
'et towards the disk and shaft decreases the operating time and moving the drag magnet away from the
l
and shaft increases the operating time.
structure must be tight before proceeding with other time checks.
GEK-45376
E G
S RVICIN
This screw shou l d be he l d secure l y in its support.
It shoul d be noted that the re l ay wil l not necessaril y
TABL E 1 3
Tap Min. Amps
0. 5
1 . 0
TAB LE 14
Time ( Seconds )
Re l ay
Min.
I FC 66
1 8. 2
The screws securing the drag magnet assemb l y to the support
14
This adjustment a l so permits any desired
If such adjustment is required, it is
See T E ST C I RCU IT Figure 1 5 .
Max. Amps.
o.
4 9 5
0. 505
0. 99
1 . 0 1
Max.
1 9. 0
The drag magnet assemb l y is
See Figure l .
The
Moving the drag
I