2.6 Dynamic Cold Load Pickup for Time Overcurrent Protection
191
7UT613/63x Manual
C53000-G1176-C160-2
2.6 Dynamic Cold Load Pickup for Time Overcurrent Protection
With the dynamic cold load pickup feature, it is possible to dynamically increase the
pickup values of the time overcurrent protection stages when dynamic cold load over-
current conditions are anticipated, i.e. in cases where consumers have increased
power consumption after a longer period of dead condition, e.g. in air conditioning sys-
tems, heating systems, motors, etc. Thus a general raise of pickup thresholds can be
avoided taking into consideration such starting conditions.
2.6.1 Function Description
The dynamic cold load pickup feature operates with the time overcurrent protection
functions as described in the above sections2.4.32.5. A set of alternative pickup
values can be set for each stage. It is selected automatically-dynamically during oper-
ation.
Note
Dynamic cold load pickup is in addition to the four setting groups (A to D) which are
configured separately.
There are two methods used by the device to determine if the protected equipment is
de-energised:
• Via a binary inputs, an auxiliary contact in the circuit breaker can be used to deter-
mine if the circuit breaker is open or closed.
• The current flow monitoring threshold may be used to determine if the equipment is
de-energised.
You may select one of these criteria for the time overcurrent protection for phase cur-
rents and for that for residual current. The device assigns automatically the correct
side or measuring location for current detection or the breaker auxiliary contact in ac-
cordance with the assignment of the associated protection functions. The time over-
current protection for earth current allows the breaker criterion only if it is assigned to
a certain side of the protective object (Section 2.1.4, margin heading „The assignment
of the 1-phase measuring inputs “); otherwise the current criterion can be used
exclusively.
If the device recognises the protected equipment to be de-energised via one of the
above criteria, then the alternative pickup values will become effective for the overcur-
rent stages once a specified time delay CB Open Time has lapsed. When the pro-
tected equipment is re-energised (i.e. the device receives input via a binary input that
the assigned circuit breaker is closed or the assigned current flowing through the
breaker increases above the current flow monitoring threshold), the active time
Active Time is initiated. Once the active time has elapsed, the pickup values of the
overcurrent stages return to their normal settings. The time may be reduced when
current values after startup, i.e. after the circuit breaker is closed, fall below all normal
pickup values for a set period of time Stop Time. The start condition for the fast reset
time is made up of an OR-combination of the dropout conditions of all time overcurrent
elements. When Stop Time is set to ∞ or binary input is active, no comparison is
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