Hysteresis; Circuit Breaker Operation Capability - Hitachi Relion 650 Series Technical Manual

1MRK 511 557-UEN Rev. A
Table 253: Alarm status bits for binary input signals
Input in phase
L1
L2
L3
Hence the alarm status for binary input 10 is 101001. This gets bit packed in ALS6T10 (in 24th to
29th bit position).
If none of these conditions are met (that is no warning or alarm), the bits are set to 0.
12.17.7.2

Hysteresis

Hysteresis is applied to prevent frequent toggling of alarms if the input signal oscillates around the
threshold by a small amount. The extent of the hysteresis zone is defined by InpxHystAbsolute for
each of the analog input signals x. This setting applies equally to all enabled thresholds for that
signal group.
• If the signal rises above one of the upper thresholds, the output will indicate this condition until
the signal drops below the level threshold minus hysteresis.
• If the signal drops below one of the lower thresholds, the output will indicate this condition until
the signal rises above the level threshold plus hysteresis.
This is demonstrated in
High Warning, High Alarm, High Warning, Normal, Low Warning, and back to Normal ranges.
Hysteresis is indicated by arrows, and small circles mark the points of output status change.
Hysteresis
IEC17000227 V1 EN-US
Figure 117: Example of analog signal passing through warning and alarm levels with hysteresis
12.17.7.3

Circuit breaker operation capability

The operation capability of the circuit breaker can be determined by the binary input signal levels for
the three phases.
For any phase,
Technical Manual
Alarm range
Warning
Alarm
High Alarm
Figure 117, showing an analog signal passing from Normal range through
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Alarm status
is set to 01
is set to 1000
is set to 100000
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High Alarm level
High Warning level
Low Warning level
Low Alarm level
IEC17000227-1-en.vsd
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Section 12
Monitoring
259