8.16
SEL-400 Series Relays Instruction Manual Date Code 20171006
Monitoring
Circuit Breaker Monitor
Figure 8.8 Pole Discrepancy Measurement
Example 8.8 Pole Discrepancy Alarm for Circuit Breaker 1—No Other Circuit
Breaker Monitor Functions
Use Circuit Breaker 1, a single-pole tripping circuit breaker, for this exam-
ple. This example uses control inputs IN301, IN302, and IN303 for the A-,
B-, and C-Phases, respectively; you can use any control inputs that are
appropriate for your installation.
The control voltage for this example is 125 Vdc. Control Inputs IN301–
IN303 are located on I/O Board #2. Connect the circuit breaker normally
open auxiliary circuit breaker (52A) contacts through station battery power
to IN301, IN302, and IN303.
Set the relay internal Relay Word bits to respond to these inputs by using the
QuickSet Breaker Monitor (SET M) settings:
52AA1 := IN301 A-Phase Normally Open Control Input—BK1
(SEL
OGIC Equation)
52AB1 := IN302 B-Phase Normally Open Control Input—BK1
(SEL
OGIC Equation)
52AC1 := IN303 C-Phase Normally Open Control Input—BK1
(SEL
OGIC Equation)
Connect external trip signals to IN301, IN302, and IN303, and external close
signals to IN304, IN305, and IN306 for the A-, B-, and C-Phases, respec-
tively. This example uses control inputs IN301–IN306; you can use any con-
trol inputs that are appropriate for your installation.
Set the pole discrepancy time delay (B1PDD) at 1400 ms. This time delay
assumes a dead time of 1000 ms plus a pole closing time of 100 ms (includ-
ing contact latency), plus 20 percent (for security), rounded to the next
higher hundreds of milliseconds value. This pole discrepancy time is longer
than the single-pole open interval time default of 900 ms; confirm that this is
the case for your application settings.
Enter the following settings:
B1PDD := 1400 Pole Discrepancy Time Delay—BK1 (1–9999 ms)
EB1MON := Y Breaker 1 Monitoring (Y, N)
BK1TYP := 1 Breaker 1 Trip Type (Single Pole = 1, Three Pole = 3)
The pole discrepancy timing window is B1PDD := 1400 (ms). Assertion of
the Relay Word bit B1PDAL indicates that the status of the three Circuit
Breaker 1 poles disagrees for 1400 ms or longer.
All Poles Open
Pole B: 52AB1
Pole C: 52AC1
Pole A: 52AA1
Pole
Discrepancy
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