ABB RELION 620 Series Technical Manual page 262

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Protection functions

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Functional module diagram

Level detector 1

This module compares the phase currents (RMS value) to the set Pickup value high

setting. If all the phase current values are less than the set Pickup value high value, the loss

of load condition is detected and an enable signal is sent to the timer. This signal is

disabled after one or several phase currents have exceeded the set Pickup value high value

of the element.

Level detector 2

This is a low-current detection module, which monitors the de-energized condition of the

motor. It compares the phase currents (RMS value) to the set Pickup value low setting. If

any of the phase current values is less than the set Pickup value low, a signal is sent to block

the operation of the timer.

Once activated, the timer activates the PICKUP output. The time characteristic is

according to DT. When the trip timer has reached the value set by Trip delay time, the

TRIP output is activated. If the fault disappears before the module trips, the reset timer is

activated. If the reset timer reaches the value set by Reset delay time, the trip 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 in the

monitored data view.

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

1MAC504801-IB E

620 series ANSI

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