ABB RELION REX640 Technical Manual page 833

Protection and control

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1MRS759142 F

Function block

Figure 470: Function block

Functionality

The phase discontinuity protection function PDNSPTOC is used for detecting

unbalance situations caused by broken conductors.

The function starts and operates when the unbalance current I

limit. To prevent faulty operation at least one phase current needs to be above the

minimum level. PDNSPTOC operates with DT characteristic.

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

output, timer or the function itself.

Analog channel configuration

PDNSPTOC has one analog group input which must be properly configured.

Table 754: Analog signals

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

blocks in this document. The configuration can be written to the protection relay

once the mismatch is corrected.

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "On" and "Off".

The operation of PDNSPTOC can be described by using a module diagram. All the

modules in the diagram are explained in the next sections.

Technical Manual

See the preprocessing function blocks in this document for the possible

signal sources.

Protection functions

Three-phase currents

Operation setting. The

exceeds the set