Basler Electric BE1-87B - Manual (Page 29)

and 7 for the three-phase model). The setting range for the alarm pickup is 10% to 80% of the rms
differential voltage pickup setting (V
DIFF
) in increments of 10%. When the rms voltage across the sensing
input terminals exceeds the voltage pickup setting times the voltage alarm percentage setting (V
DIFF
x %
set), the CT OV LED illuminates and the alarm output contact closes (Terminals 13 and 14). When the
input voltage falls below the alarm voltage threshold, the CT OV LED turns OFF and the alarm output
contacts open. The response time of the alarm contacts and the LED is intentionally slow to prevent
nuisance alarms (approximately one second). If the Shorted CT Test Circuit is used, set the alarm unit at
minimum (10%).
Example:
A relay with a differential pickup voltage (V
DIFF
) setting of 200 volts rms symmetrical and an imbalance
alarm voltage setting of 10%, will alarm at 20 volts rms (200 x 0.1 = 20 volts).
Trip Test Pushbutton
The Trip Test pushbutton is recessed behind the front panel and is accessed through a small opening.
Insert a small, nonconductive tool through the front panel to depress the Trip Test pushbutton. Trip test
simulates a trip condition and verifies the operation of both output trip contacts and the trip LED. Upon
releasing the Trip Test pushbutton, the trip output contacts will reset, but the LED remains lit. To clear the
Trip LED indication, press the Reset button.
CAUTION
Activation of the Trip Test button will trip the lockout device (86) and the bus
breakers unless appropriate steps are taken.
CT Test Pushbutton
The CT Test pushbutton is a “pillow-type” button located on the face of the relay. The button can be
accessed by either removing the standard cover to actuate or through the external button actuators of the
optional cover. The CT Test pushbutton provides a method for testing the “health” of the entire current
circuit by injecting a calculated value of external test voltage across the current circuit. If the current circuit
is healthy, the voltage across the relay will be high enough to light the Alarm LED and close the alarm
output contacts, terminals 13 and 14. If there is a short circuit in the current circuit, all of the test voltage
will be dropped across an external test resistor and neither the LED nor the alarm output will operate. If
this occurs, further current circuit tests should be performed. This function is available only when power is
applied to the relay and the CT diagnostic test source assembly (9282300014) is connected to terminals 7
and 10 of the relay. The Test Circuit Calculations sub-section provides details on applying this feature.
Power LED
This LED lights when normal operating power is applied to relay terminals 15 and 16.
Intentional Delay Jumper
A user-settable jumper is located on the Control circuit board to select either no intentional delay (jumper
position 1 to 2), or a 20-millisecond delay
∗ (jumper position 2 to 3) added to the trip response time. For
applications having a tap within the zone of protection that is protected by a high-speed fuse, the 20
millisecond intentional delay
∗ is intended to prevent tripping the bus for a fault on the fused tap. The
current detector circuit reset time is approximately 1 millisecond so that the ac and dc components of the
differential current, as reproduced at the CT secondary, must drop below pickup in less than 19
milliseconds. A secondary error may occur due to the fast dropout of the primary current when the fuse
operates.
∗ Actual intentional time delay is a function of pickup current. For currents exceeding twice the pickup
setting, intentional time delay is 20 milliseconds. For currents less than twice the pickup setting,
intentional time delay is 25 milliseconds.
Operating Times
The BE1-87B operates in less than 7 milliseconds (1/2 cycle) for faults 1.5 times the current pickup. The
BE1-87B operates in less than 5.5 milliseconds for fault levels above 6 times the current pickup. High-
9282300990 Rev P BE1-87B Application 2-11