GEK-49849
I NSTANTANEOUS OVERCURRENT UNI T
The pickup of the in stantaneou s overcurrent unit can be adju sted over an
eight-to- one r ange, as indicated in T ab l e 6, by varying the ten sion of the spiral
control spring and by sel ection of the appropriate series or p aral l e l connections . The
outside end of this spring is fastened to a post on the adjusting ring above the moving
contact, an d the ring is in turn c l amped in position by a hex agonal -head l ocking screw.
If this screw is l oosened, the ring can be s l ipped to vary the spring ten s ion .
Make test connections as shown for the app l ic ab l e rel ay type by Fig . 24 .
I n
adju sting pickup, the desired pick up current shou l d be pas s sed through the coil s and
the contro l spring shou l d be adju sted u ntil the contact ju st c l oses . The adjusting
ring shou l d then be l ocked in position and the pick up current rechecked . Note that the
directional -unit contacts must be hel d c l osed during this adjustment.
I NSTANTANEOUS UNIT
Make sure that the instantaneous u nit is in the c orrect r ange in which it is to
operate . See the intern a l connections diagr am and T abl e 7 . Whenever possibl e, use the
higher range since the higher range has a higher continuous ratin g .
The instantaneous unit has an adju stab l e core l ocated a t the top of the unit. To
set the instantaneous unit to a desired pick up, l oosen the l ocknut and adju st the core.
Turning the c ore c l ockwise decreases the pick up, tur ning the c ore counter c l ockwise
increases the pick up . Bring up the c urrent s l owly until the u nit pick s u p . It may be
necessary to repeat this operation, u ntil the desired pick u p val ue is obtaine d . Once
the desired pickup val ue is reached, tighten the l ocknut.
CAUT ION:
Refer to T abl e 7 for the contin uous and one second r atings of the
instantaneous unit. Do not exceed these r atings when app l ying current to
the in stantaneous u nit.
The range of the in stantaneous unit ( see Tab l e 7 ) must be obtained between a core
position of 1 /8 of a turn of f u l l c l ockwise, and 20 turns counterc l ockwise from the
fu l l c l ockwise p ositio n .
INSTALLAT I ON
LOCATI ON
The l ocation shou l d be c l ean and dry, free from dust and exces sive vibration and
we l l l ighted to facil itate in spection and testin g .
MOUNT I NG
The re l ay shou l d be mounted on a vertica l surface . The outl ine and p an e l dril l ing
diagram is shown in Fig . 25 .
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