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.
www.eaton.com 552
To Next Page
Loading...
Need help?
General
