8.13
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Monitoring
Circuit Breaker Monitor
The relay further checks the circuit breaker by testing whether the circuit breaker
has interrupted or restored current within 100 ms after the end of the trip or close
threshold times. Thus, this additional check serves as the trip time-out and close
time-out condition. This verifies that the circuit breaker actually closed or
opened, and alerts you if maintenance is required on circuit breaker mechanical
linkages.
Pole Scatter
The relay records and compares the operation time of each circuit breaker pole to
detect time deviations between pairs of circuit breaker poles when tripping and
closing all three poles simultaneously on single-pole-capable circuit breakers.
The relay measures the differences in operating times resulting from auxiliary
circuit breaker (52A) contact status changes. The logic compares the operation
time of each individual circuit breaker pole against the time for each of the other
poles. The relay triggers an alarm, B1PSAL, for any time deviation greater than
the preset time threshold settings B1PSTRT and B1PSCLT for Circuit Breaker 1.
NOTE: Pole scatter applies only to
single-pole mechanism circuit
breakers (BK1TYP := 1). These circuit
breakers have an auxiliary circuit
breaker (52A) contact for each phase.
Figure 8.7 shows the operating time for each pole (A, B, and C) of Circuit
Breaker 1. TAB represents the operating time deviation between poles A and B.
TBC is the time between B and C, and TCA is the time between C and A. Once
activated, the pole scatter alarm remains asserted for five seconds.
BM1CLSB := BK1CL OR IN205 Breaker Monitor B-Phase Close—BK1
(SEL
OGIC Equation)
BM1CLSC := BK1CL OR IN206 Breaker Monitor C-Phase Close—BK1
(SEL
OGIC Equation)
Assertion of the Relay Word bit B1ESOAL indicates any one of the follow-
ing four conditions:
➤ The electrical operating time for a trip operation exceeds 25 ms
(the slow trip alarm setting)
➤ The electrical operating time for a close operation exceeds 65 ms
(the slow close setting)
➤ No pole-open logic status change occurred during the time
B1ESTRT plus approximately 100 ms after trip initiation (a trip
time-out condition)
➤ No pole-open logic status change occurred during the time
B1ESCLT plus approximately 100 ms after close initiation (a
close time-out condition)
Example 8.6 Electrical Operating Time Settings (Continued)
Figure 8.7 Timing Illustration for Pole Scatter at Trip
All Poles Closed All Poles Open
Pole B: 52AB1
Pole C: 52AC1
Pole A: 52AA1
TBC
TCA
TAB
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