8.8
SEL-400 Series Relays Instruction Manual Date Code 20171006
Monitoring
Circuit Breaker Monitor
Example 8.4 Using a Control Input to Capture External and Internal Trip
Commands
You can also capture all trip information for circuit breaker trips by using a
relay control input to monitor the trip bus for the given circuit breaker.
Figure 8.4 shows an illustration of this method in which IN206 connects to
the Circuit Breaker 1 A-Phase trip bus (via a parallel connection across the
trip bus), and asserts for any trip from any source. This example uses inputs
IN206; you can use any control inputs that are appropriate for your installa-
tion. Vdc for this example is 125 Vdc.
Many U.S. substation trip bus configurations have an incandescent trip indi-
cator lamp from the battery + terminal to the trip bus. This lamp presents an
impedance that can provide sufficient “pull-up” on the trip bus to falsely
assert the control input. The worst case for this condition occurs when the
circuit breaker is open (auxiliary circuit breaker (52A) contact in Figure 8.4
is open). You can change the input debounce time IN206PU for slow or
noisy mechanical switches; the default debounce time of 1/8 cycle should be
sufficient for most trip bus arrangements.
Use the SET G (GLOBAL) command or the QuickSet Global > Control
Inputs Settings tree view to confirm that the debounce time (settings
IN206PU and IN206DO) are correct for your trip bus control voltage. You
must enable independent control input conditioning by using Global setting
EICIS. Enter these settings:
EICIS := Y Independent Control Input Settings (Y, N)
IN206PU := 0.1250 Input IN206 Pickup Delay (0.0000–5 cyc)
IN206DO := 0.1250 Input IN206 Dropout Delay (0.0000–5 cyc)
BM1TRPA := IN206 Breaker Monitor Trip—BK1 (SEL
OGIC Equation)
Use this procedure to cause the circuit breaker monitor to initiate for either
external or internal Circuit Breaker 1 A-Phase trips.
Figure 8.4 Trip Bus Sensing With Relay Input IN206
Other
External
Trips
CS/T
(Control Switch Trip)
52A
Trip
Coil
(+)
(-)
IN206
Relay
OUT201 := TRIP
TC
Trip Bus
Incandescent Lamp
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