4.17
Date Code 20171021 Instruction Manual SEL-421 Relay
Front-Panel Operations
One-Line Diagrams
The Bay Control indicates the status of breakers in the one-line diagrams. The
setting EPOLDIS, Enable Single-Pole Discrepancy Logic, controls the behavior.
If the breaker is a single-pole type, Global Setting BKnTYP = 1, where n is 1 or 2,
the breaker status will be determined based on the EPOLDIS setting. If
EPOLDIS = Y, then the breaker status is indicated by the Relay Word bits 52ACLn,
52BCLn, and 52CCLn, which check for current to determine the breaker status.
This setting is useful to identify a pole discrepancy, where a pole may not open
but the other two do. In this case, the breaker status would display a pole discrep-
ancy screen as shown below in Figure 4.14. If EPOLDIS = N, the single-pole dis-
crepancy logic is disabled, and the breaker status will follow the 52nCLSM
SEL
OGIC setting.
Figure 4.13 Configuring PB1_HMI for Direct Bay Control Access
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