ABB 615 series Technical Manual page 610

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Protection functions

GUID-F890E844-B9C9-4E99-A51F-6EAB19B5239B-ANSI V2 EN

Functional module diagram

Level detector

The calculated negative-sequence current is compared to the Pickup value setting. If the

measured value exceeds the Pickup value setting, the function activates the timer module.

Once activated, the timer activates the PICKUP output. Depending on the value of the set

Operating curve type, the time characteristics are according to DT or IDMT. When the

operation timer has reached the value set by Trip delay time in the DT mode or the

maximum value defined by the inverse time curve, the TRIP output is activated.

In a drop-off situation, that is, when the value of the negative-sequence current drops

below the Pickup value setting, the reset timer is activated and the PICKUP output resets

after the time delay of Reset delay time for the DT characteristics. For IDMT, the reset

time depends on the curve type selected.

For the IDMT curves, it is possible to define minimum and maximum trip times with the

Minimum trip time and Maximum trip time settings. The Machine time Mult setting

parameter corresponds to the machine constant, equal to the I

as stated by the machine manufacturer. In case there is a mismatch between the used CT

and the protected motor's nominal current values, it is possible to fit the IDMT curves for

the protected motor using the Rated current setting.

The activation of the TRIP output activates the BLK_RESTART output. The deactivation

of the TRIP output activates the cooling timer. The timer is set to the value entered in the

Cooling time setting. The BLK_RESTART output is kept active until the cooling timer is

exceeded. If the negative-sequence current increases above the set value during this

period, the TRIP output is activated immediately.

The T_ENARESTART output indicates the duration for which the BLK_RESTART output

remains active, that is, it indicates the remaining time of the cooling timer. The value is

available in the monitored data view.

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615 series ANSI

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