Application; Signals - ABB 615 series Technical Manual

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1MAC059074-MB A

615 series ANSI

Technical Manual

If the reset timer reaches the value set by Reset delay time, the operation timer resets and

the PICKUP output is deactivated.

The timer calculates the pickup duration value PICKUP_DUR, which indicates the

percentage ratio of the pickup situation and the set trip time. The value is available through

the monitored data view.

The BLOCK signal blocks the operation of the function and resets the timer.

Application

In some cases, smaller distribution power transformers are used where the high-side

protection involves only power fuses. When one of the high-side fuses blows in a single-

phase condition, knowledge of it on the secondary side is lacking. The resulting negative-

sequence current leads to a premature failure due to excessive heating and breakdown of

the transformer insulation. Knowledge of this condition when it occurs allows for a quick

fuse replacement and saves the asset.

The Current block value setting can be set to zero to not block 37 with a low three-phase

current. However, this results in an unnecessary event sending when the transformer or

protected object is disconnected.

Phase-specific pickup and trip can give a better picture about the evolving faults when one

phase has picked up first and another follows.

37 is meant to be a general protection function, so that it could be used in other cases too.

In case of undercurrent-based motor protection, see the Loss of load protection.

37 Input signals

Phase A current

Phase Bcurrent

Phase C current

Block all binary outputs by resetting timers

Protection functions

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