4.4.3.2 Function block
Figure 470: Function block
4.4.3.3 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
2
/I
1
exceeds the set
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.
4.4.3.4 Analog channel configuration
PDNSPTOC has one analog group input which must be properly configured.
Table 754: Analog signals
Input Description
I3P Three-phase currents
See the preprocessing function blocks in this document for the possible
signal sources.
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.
4.4.3.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. 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.
1MRS759142 F
Protection functions
REX640
Technical Manual
833
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