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NPT957 - Transformer Protection IED

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NPT957 - Transformer Protection IED

Multi-Function Protection
Regulation PLC
The NPT957 is a transformer protection device with a differential protection function and an integrated automatic voltage regulator function.
The relay also provides complete current-based and voltage-based protection functions as well as full measurements.
You can add up to total 9 optional modules (I/O and other type of modules) into the device for extensive monitoring and control applications. The NPT957 communicates using various protocols, including the IEC 61850 substation standard.
  • A large I/O capacity.
  • Automatic/manual voltage regulation and/or parallel voltage regulation (AVR).
  • Complete transformer protection functionality.
  • 2nd and 5th harmonic blocking.
  • Automatic verification of connection group and nominal value settings.
  • Overloading and through fault statistics for preventive maintenance.
Product family: 
IEC 61850 - Protection and Control Relays
ANSI code : 
50/51 - Three phase overcurrent protection
50N/51N - Earth tank protection
67 - Phase directional overcurrent
67N - Earth directional overcurrent
32N - Directional earth fault
46/46R/46L - Current unbalance / broken conductor protection
50H/51H/68H - Harmonic overcurrent protection / inrush blocking
50BF - Breaker failure with overcurrent
52BF - Breaker failure protection with position rise
59 - Overvoltage
27 - Undervoltage
59N - Maximum of zero sequence voltage
47/27P/59NP - Positive sequence under/overvoltage protection
81O - Over frequency
81U - Under frequency
81R - Rate of change frequency
32 - Directional power
24 - Overfluxing
RTD - Resistance temperature detectors
49T - Thermal overload for transformer
87T - Transformer differential relay
87M - Machine differential relay
87G - Generator differential relay
99 - Programmable functions
50ARC - Arc protection
50NARC - Arc protection
78 - Vector jump / surge
90 - Voltage regulator
CTS - Current transformer supervision
CBW - Circuit breaker wear monitoring
THD - Current total harmonic distortion
THD - Voltage total harmonic distortion
21FL - Fault locator
60 - Fuse failure
SOTF - Switch-on-to-fault
TRF - Transformer status monitoring

NP950 Series


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