GE IAC77A, Руководство пользователя, Страница: 7 / 56

GEK-34055
CONSTRUCTION
rhe induction unit is the basic unit in all Type lAC relays. Figs. 2 and 3 show the induction unit
mouu,ed in the cradle. These units are of the induction-disk construction type.
The disk is actuated by a wattmetric type current operating element. This is similar to the standard
element as used in watthour meters, except the actuating coils·above and below the operating disk are
connected in series. A capacitor and variable resistor connected in series with the inner coil on the
upper laminated structure makes up the phase-shifting circuit. The disk shaft carries the moving contact
which completes the trip or alarm circuit. The disk shaft is restrained by a spiral spring to give proper
contact closing current and its motion is retarded by a permanent magnet acting on the disk to give
correct time delay.
There is a target and seal-in unit mounted on the front to the left of the shaft of the time over-
-
current unit. The seal-in unit has its coil in series and its contacts in parallel with the contacts
�
of the time overcurrent unit such that when the induction unit contacts close the seal-in unit picks up
and seals in. When the seal-in unit picks up, it raises a target into view which latches up and remains
exposed until released by pressing a button beneath the lower left corner of the cover.
The instantaneous unit is a small hinge type unit which may be mounted on the front to the right
of the shaft of the time overcurrent unit. Its contacts are normally connected in parallel with the
contacts of the time overcurrent unit and its coil is connected in series with the time overcurrent unit.
When the instantaneous unit picks up, it raises a target which latches up and remains exposed until it is
released. The same button that releases the target of the seal unit also releases the target of the
instantaneous unit.
Tr
OVE RCURRENT UNIT
RATINGS
(atings of the time overcurrent unit are given in Table II.
TABLE II
PICK UP RANGE, AMPERES
RELAY
FREQ. MAIN (TIME)
INSTANTANEOUS
CYCLES
UNIT
UNIT
IAC77A and
50
0. 5 - 4.0
IAC78A 60
1. 5-12.0
2.0-
IAC77B and
50
0. 5 - 4.0 0. 5 - 4. 0
IAC78B
60
1. 5 - 12.0
2.0 - 16. 0
2. 0 - 15. 0
10.0 - 80.0
20. 0 - 160. 0
Available taps of the time overcurrent unit are shown on Table II.
TABLE I II
RAN GE
TAPS AVAILABLE (AMPE RES)
AMPERES
0. 5 - 4. 0 0. 5,0. 6,0. 7,0.8,1. 0, 1. 2, 1.5,2.0, 2.5, 3. 0,4.0
1. 5 - 12. 0 1. 5, 2. 0, 2. 5, 3.0,4.0,5. 0,6. 0,7. 0,8.0, 10.0, 12. 0
2. 0 - 15. 0
2. 0, 2. 5, 3. 0, 4. 0,5. 0,6. 0,7. 0,8. 0,10. 0,12. 0,15. 0
4
0
www . ElectricalPartManuals
. com
www
. ElectricalPartManuals
. com