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2.39.1 Scheme logic
State transition diagram and scheme logic are shown in Figure 2.39-1 and Figure 2.39-2. It
should be noted that the scheme logic requires two binary inputs: circuit breaker (CB) OPEN
and circuit breaker (CB) CLOSED.
Under the normal operation, where the CB is closed, the CLP stays in STATE 0, and the
OC operates with a normal setting group.
When the CB opens, the scheme moves into STATE_1, then Cold-load-enable-timer
(TCLP) runs. If the CB closes again while the TCLP is running, the scheme will re-enter into
STATE_0. If the TCLP expires and the load is in cold, the scheme moves into STATE_2. When
the CB closes again, the scheme moves into STATE_3.
Cold-road-reset-timer (TCLP) runs at STATE_3. If the CB re-opens while the TCLP is
running, the scheme returns into STATE_2. If the TCLP is time out, the scheme moves into
STATE_0, where the load is considered as warm, and the setting of normal operation is applied
again.
At STATE_2 and STATE_3, the setting group of the CLP is applied. The operation of the
CLP is forbidden by placing set of OFF for the scheme switch [CLP-EN].
Accelerated reset of the CLP is also possible. As being at STATE_3, poly-phase currents
are monitored by the function of inrush current detection (ICD). If poly-phase currents plunge
below the setting of ICD threshold, and when the duration of the plunge is longer than setting
[TCLP_DO], then the scheme automatically reverts into STATE_0. By placing set of ON for
scheme switch [CLP-DOEN], it is possible for the reset function to accelerate.
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