ABB RELION REX640 Technical Manual page 826

Protection and control

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Protection functions

Function block

Figure 467: Function block

Functionality

The directional negative-sequence overcurrent protection function DNSPDOC is

used as directional overcurrent and short-circuit protection.

DNSPDOC starts up when the fundamental value of the operating quantity

(negative-sequence or residual current) exceeds the set limit and the directional

criterion is fulfilled. The operate time characteristic is according to definite time

The function contains a blocking functionality. It is possible to block function

outputs, timers or the function itself.

Analog channel configuration

DNSPDOC has three analog group inputs which must be properly configured.

Table 743: Analog inputs

There are a few special conditions which must be noted with the configuration.

Table 744: Special conditions

U3P connected real measurements

Improper analog channel configuration causes a validation error if the analog

channels are not completely configured or they do not match with certain settings.

For troubleshooting, check the contents of this chapter and also the preprocessing

Can be connected to GRPOFF if

See the preprocessing function blocks in this document for the possible

signal sources. The GRPOFF signal is available in the function block called

Operating quantity is set to "Negative seq"

Three-phase currents

Residual current (measured or calculated)

Necessary when

Operating quantity is "Re-

sidual" or "Residual (calc)"

Three-phase voltages

The function requires that at least two volt-

age channels are connected.

1MRS759142 F

Technical Manual