Application - ABB RELION REX640 Technical Manual

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1MRS759142 C

Technical Manual

Once activated, Timer runs until the set Operate delay time value is exceeded. The

time characteristics is according to DT. When the operation timer has reached the

Operate delay time value, the Timer module output is activated. If the timer has

elapsed and the inrush situation still exists, the Timer module output remains active

until the I_2H/I_1H ratio drops below the set Start value, that is, until the inrush

situation is over. If the drop-off situation occurs within the operate time up counting,

the reset timer is activated. If the drop-off time exceeds Reset delay time, the operate

timer is reset.

The BLOCK input can be controlled with a binary input, a horizontal communication

input or an internal signal of the relay program. The activation of the BLOCK input

prevents the BLK2H output from being activated.

Phase selection logic

This module determines the number of phases used for activating the BLK2H output.

If Num of start phases = "1 out of 3", an inrush on any of the phases activates output

BLK2H. If the set value equals "2 out of 3", an inrush or at least two phases are required

to activate output BLK2H.

Application

Transformer protections require high stability to avoid tripping during magnetizing

inrush conditions. A typical example of an inrush detector application is doubling the

start value of an overcurrent protection during inrush detection.

The inrush detection function can be used to selectively block overcurrent and earth-

fault function stages when the ratio of the second harmonic component to the

fundamental component exceeds the set value.

Other applications of this function include the detection of inrush in lines connected

to a transformer.

Protection related functions

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