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1MRS 751108-MUM

REX 521

Protection Relay

Technical Reference Manual, General

Fig. 4.1.7.1.-1 Filtering of a digital input

The figure above illustrates the input filtering. At the beginning, the input signal is

at high state, the first low state is filtered and no input status change is detected. The

second low state is longer than the set filter time, thus detected as a change and

attached with the time tag t

.When the input signal returns to high state, after the

filter time, the state is accepted and attached with the time tag t

Each digital input has a filter time parameter Input # filter

(Configuration\Digital inputs\Input filtering), where # is the

number of the input.

A risk for debounces and short disturbances on digital inputs grows if the input filter

time is changed to less than the default value.

4.1.7.2. Inversion of digital inputs

The status of digital inputs can be inverted with parameters accessible through the

HMI or the Relay Setting Tool (Configuration\Digital inputs\Input

inversion). When inverted, the status of a digital input is TRUE (1) when no

control voltage is applied to the terminals, and FALSE (0) when the control voltage

is applied.

4.1.8. Outputs

The outputs are categorized as follows:

• HSPO: High speed power output, single or double pole contact, for example for

tripping purposes

• PO: Power output, single pole contact

• SO: Signal output, NO/NC (Normally open/Normally closed) contact

For detailed information about terminal connections, refer to the terminal diagrams.

Technical data of the outputs is found in the section “Technical data” on page 44.

Table 4.1.7.1-1 Filter time parameter

Parameter Values Default

Input # filter 1...65535 ms 5 ms

dipo_rex

Filter Time

Filtered Input

Input

Filter Time

Filter

ABB REX 521 Technical Reference Manual, General

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