5-14
BE1-51/27R - Tests And Adjustments
NOTE
Because the lower limit for this pickup is determined by the front panel TAP selector
setting and the front panel TAP (CAL) control position, ensure that these adjustments
have been performed as in the paragraph TAP AND TAP (NEUTRAL) Selector Setting
(page 5-11).
CAUTION
Steps 3 through 8 provide the application of overcurrent for short periods of time to allow
adjustment while avoiding overheating of the input sensing transformers. To avoid
damaging the relay, do not attempt to apply a constant high level of input current for ad-
justment of the front panel INST 1, INST 1 (NEUTRAL), or INST 2 controls.
NOTE
For relays with two-phase-and-neutral or three-phase-and-neutral sensing (sensing input
types E, F, U, W, Y, or Z), perform Steps 9 through 14.
b. Using Figure 1-6 as an example, if the overcurrent is expected to be 4 times the pickup
point value and time delay of 4 seconds is desired, plot upward from the point 4 on the
multiples-of-pickup-current axis until the point 4 from the time-in-seconds axis is
crossed. The curve for a setting of 52 crosses the plot point and should be entered on the
front panel NEUTRAL TIME DIAL.
c. For a lesser overcurrent difference from the pickup point, the time delay will be greater, so
that for a multiple of 3 times the pickup current, the time delay for the previous front panel
setting of 52 will be 5.8 seconds.
INST 1 Control Setting
Step 1.
Verify that the test setup is as described in TAP and TAP (NEUTRAL) Selector Setting, Steps 1
through 6.
Step 2.
Connect the test setup to the instantaneous 1 element output terminals (2 and 10) as shown in
Figures 5-1 through 5-6. The timer should not be connected.
Step 3.
Set the front panel INST 1 control to a position approximating the desired instantaneous 1
overcurrent pickup point for the relay.
Step 4.
Apply current to the relay.
Step 5.
Rapidly increase the overcurrent input to the relay until the instantaneous output relay just
energizes. Note the overcurrent threshold reading on the ammeter.
Step 6.
Remove input current.
Step 7.
Reset the INST TARGET (if present).
Step 8.
If the overcurrent threshold reading from Step 5 was too high or low, adjust the front panel INST
1 control CCW to lower (or CW to raise) the instantaneous 1 overcurrent pickup point. Repeat
Steps 4 through 8. If the overcurrent threshold reading from Step 5 was NOT too high or low,
proceed to Step 9.
Step 9.
Reconnect the output to the neutral current sense terminals. See Figures 5-3, 5-5, or 5-6.