5-10
BE1-51 Tests and Adjustments
9137200997 Rev D
Time Delay Selection
Step 1.
Referring to the appropriate time overcurrent characteristic curve, select the desired time delay
on the front panel
TIME DIAL
for the anticipated input overcurrent difference (multiples-of-
pickup current) from the selected time overcurrent pickup point as follows:
(Selected Pickup Point) - (Anticipated Input Overcurrent) = Overcurrent Difference from Pickup
Step 2.
Set the front panel
TIME DIAL
as follows:
(a) On the appropriate curve, plot upward from the
multiples-of-pickup-current
value until the
horizontal line opposite the desired time delay
(time-in-seconds)
is reached. The setting
curve nearest the plot point should then be entered on the front panel
TIME DIAL
.
(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
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.
Neutral Time Delay Selection
Step 1. Use the same characteristic curve used in the previous paragraph (
Time Delay Selection
).
However,
the multiples-of-pickup current, time-in-seconds,
and the resulting front panel
NEUTRAL TIME DIAL
setting can differ.
Step 2.
Set the front panel
NEUTRAL TIME DELAY
as follows:
(a) On the appropriate curve, plot upward from the
multiples-of-pickup-current
value until the
horizontal line opposite the desired time delay
(time-in-seconds)
is reached. The setting
curve nearest the plot point should then be entered on the front panel
NEUTRAL TIME
DELAY
.
(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
NOTE
If Timing Type Z1, Z2, or Z3 is installed, refer to time overcurrent curve selection
to obtain the desired set of time overcurrent curves (see Figures A-1 through A-
69). Then proceed to Step 1, following.
If Timing Type Z1, Z2, or Z3 is not installed, determine the timing type from the
model and style number for a specific relay. Then select the appropriate timing
curve (see Figures A-1 through A-69). Proceed to the following, Step 1.
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.
