EDR-5000
IM02602007E
CLPU - Supervision Module Cold Load Pickup
Available Elements:
CLPU
When manually or automatically closing a breaker after it has been open for a prolonged time, a greater than normal
load current may be experienced due to the load inrush . This high starting current causes some overcurrent elements
to unnecessarily trip the breaker. The cold load pickup (CLPU) function prevents this from happening.
The cold load pickup function detects a warm-to-cold load transition according to the four selectable cold load detection
modes:
•
Breaker state;
•
Undercurrent (I<);
•
Breaker state AND undercurrent; and
•
Breaker state OR undercurrent.
After a warm-to-cold load transition has been detected, a specified load-off timer will be started. This User-settable
load-off timer is used in some cases to make sure that the load is really “cold” enough. After the load-off timer times
out, the CLPU function issues an “enable” signal »CLPU.
ENABLED
« that can be used to block User-selected, sensitive
protection elements such as instantaneous overcurrent elements, current unbalance, or power protection elements.
Using this enable signal, some User-selected time inverse overcurrent elements may also be desensitized by means of
activating adaptive settings of the corresponding overcurrent elements.
When a cold load condition is finished (a cold-to-warm load condition is detected) due to, for example, breaker closing
or load current injection, a load inrush detector will be initiated that supervises the coming and going of the load inrush
current process. A load inrush is detected if the coming load current exceeds a User-specified inrush current threshold.
This load inrush is considered as finished if the load current is decreased to 90% of the inrush current threshold.
After the inrush current is diminished, a settle timer starts. The cold load pickup enable signal can only be reset after
the settle timer times out. Another max-Block timer, which is started parallel with the load inrush detector after a cold
load condition is finished, may also terminate the CLPU enable signal if a load inrush condition is prolonged abnormally.
The cold load pickup function can be blocked manually by external or internal signal at the User´s choice. For the
devices with the Auto-Reclosing function, the
CLPU function will be blocked automatically if auto-reclosure is initiated
(AR is running).
This module issues a signal only (it is not armed).
In order to influence the tripping settings of the overcurrent protection, the User has to
assign the signal “CLPU
.
ENABLED
“ to an adaptive parameter set. Please refer to the
Parameter / Adaptive Parameter Sets section. Within the adaptive parameter set, the
User has to modify the tripping characteristic of the overcurrent protection according to
the needs.
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