4.3.8 High-impedance or flux-balance based differential
protection MHZPDIF (ANSI 87HIM)
4.3.8.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
High-impedance or flux-balance
based differential protection
MHZPDIF 3dIHi>M 87HIM
4.3.8.2 Function block
Figure 458: Function block
4.3.8.3 Functionality
The high-impedance/flux-balance based differential protection for motors function
MHZPDIF provides winding short circuit protection for motors.
MHZPDIF starts and operates when any of the three-phase differential currents,
ID_A, ID_B or ID_C, exceeds the set limit. The operation timer characteristic is
according to the definite time (DT).
This function contains a blocking functionality. It is possible to block the function
outputs, timers or the function itself.
4.3.8.4 Analog channel configuration
MHZPDIF has one analog group input which must be properly configured.
Table 724: Analog inputs
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.
Protection functions
1MRS759142 F
806 REX640
Technical Manual
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