Siemens siprotec SJ62 User Manual page 120

Figure 2-33 Timing charts of the dynamic cold load pickup function
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
active, no comparison is made with the "normal" thresholds. The function is inactive
and the fast reset time, if applied, is reset.
If overcurrent elements are picked up while time Active Time is running, the fault
generally prevails until pickup drops out, using the dynamic settings. Only then the pa-
rameters are set back to "normal".
When the dynamic setting values are activated via the binary input „>ACTIVATE
CLP" or the signal "79M Auto Reclosing ready" and this causes drops out, the "nor-
mal" settings are restored immediately, even if a pick up is the result.
When binary input „>BLOCK CLP" is enabled, all triggered timers will be reset and,
as a consequence, all "normal" settings will be immediately restored. If blocking
occurs during an on-going fault with dynamic cold load pick-up functions enabled, the
timers of all non-directional overcurrent relay elements will be stopped, and may then
be restarted based on their normal duration.
During power up of the protective relay with an open circuit breaker, the time delay CB
Open Time is started, and is processed using the "normal" settings. Therefore, when
the circuit breaker is closed, the "normal" settings are effective.
Figure 2-33 illustrates the timing sequence. Figure 2-34 shows the logic diagram of
the dynamic cold load pickup feature.
2.4 Dynamic Cold Load Pickup
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