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GEK-49850
Pickup Test
Use rated frequency for both the pickup and time tests.
Set the relay at the 0.5 time dial position and 2.0 ampere tap.
Using the test connections in Fig. 20
the main unit should close its contacts within '-2.0 percent of tap value current (1.96-2.04 amps).
Time Test
Set the relay at No. 5 time dial setting and the 2.0 amp tap.
Using the test connections of Fig. 20,
apply five times tap current (10.0 amp) to the relay.
The relay should operate within the limits shown
in Table 13.
TABLE 13
TOC UNIT OPERATING TIME LiMITS
Time in Seconds
Relay Type
Mm.
Midpoint
Max.
JBCV51
1.72
1.78
1.83
JBCV53
1.27
1.31
1.35
JBCV77
0.89
0.92
0.95
DIRECTIONAL UNIT
Polarity Check
The polarity of the external connections to the operating and polarizing circuits of the directional
unit may be verified by disconnecting the external connections to the restraint circuit and observing the
direction of contact armature torque when the line is carrying load at unity power factor, or slightly
lagging power factor.
Note that in most directional overcurrent relay applications, the desired directions
are:
contact closing for power flow away from the bus, and contact opening for power flow toward the bus.
In case of doubt, refer to Fig. 21 for a more accurate method of checking the polarity of the external
connections to the operating and polarizing circuits.
Note that, during this test, the restraint circuit
is automatically disconnected by means of the test plug.
The polarity of the restraint circuit is automatically checked when it is reconnected, or when the
test plug is removed and the connection plug is reinserted.
With normal load and rated voltage, the
restraint circuit should always cause the directional unit contacts to open regardless of the direction of
power flow.
Fig. 22 shows the test connections for checking the polarity of the directional unit itself.
INSTANTANEOUS OVERCURRENT UNIT (DIRECTIONALLY CONTROLLED)
Pickup Setting
The pickup of the instantaneous overcurrent unit can be adjusted over an eight—to-one range, as indi
cated in Table 5, by varying the tension of the spiral control spring and by selection of the appropriate
series or parallel connections.
The outside end of this spring is fastened to a post on the adjusting
ring above the moving contact, and the ring is in turn clamped in position by a hexagonal-head locking
screw.
If this screw is loosened, the ring can be slipped to vary the spring tension.
Make test connections as shown for the applicable relay type by Fig. 23.
In adjusting pickup, the
desired pickup current should be passed through the coils and the control spring should be adjusted until
the contact just closes.
The adjusting ring should then be locked in position and the pickup current re
checked.
Note that the directional—unit contacts must be held closed during this adjustment.
14
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