Time Overcurrent Unit; Current Setting - GE IBCG51M A Series Instructions Manual

TIME OVERCURRENT UNIT

Rotate the time dial slowly and check by means of a lamp that the contacts just close
at the zero time dial setting.
Where the contacts just close can be adjusted by running the stationary contact
brush in or out by means of its adjusting screw.
its support.
With the contacts just closing at No. 0 time setting, there should be sufficient gap
between the stationary contact brush and
approximately l/32 inch wipe.

Current Setting

The minimum current at which time overcurrent unit will close its contacts
determined by the position of the plug in the tap block. The tap plate on this block is
marked in amperes, as shown in Tables 3, 4 and 5.
When the tap setting is changed with the relay energized in its case, the following
procedure must be followed:
relay and shorts the current transformer secondary winding.
and place it in the tap marked for the desired pickup current.
connecting plug.
The minimum current required to rotate the disk slowly and to close the contacts
should be within five percent of the value marked on the tap plate for any tap setting
and time dial position.
means of the spring adjusting ring.
blade in the notches around the edge.
unit can be brought into agreement with the tap setting employed. This adjustment also
permits any desired setting to be obtained intermediately between the available tap
settings.
Pickup adjustment by means of the control spring applies to the
relays.
relays, the pickup of the unit for any current tap setting is adjusted by
means of the variable resistor in the phase-shifting circuit.
permits any desired setting intermediately between the various tap settings to be
obtained.
The control spring is prewound approximately 660 degrees with the contacts
just closed.
Further adjustment of this setting is seldan required; if it is required,
GEK-49822
TABLE
TARGET AND SEAL-IN UNIT OPERATING CURRENTS
PICKUP
CURRENT
TAP
0.2 0.115
2.0 1.15
(1) Remove the connecting plug; this de-energizes the
this adjustment has been disturbed, it can be restored by
If
The ring can be turned by inserting a screw driver
By turning the ring, the operating current of the
A different procedure applies to the
11
DROPOUT
CURRENT
0.05 OR MORE
0.55 OR MORE
This screw should be held securely in
its metal backing strip to ensure
15
(2) Remove the tap screw
(3) Replace the
relays. For the
This adjustment also
and