NA21

Feeder protection

The relay type NA21 is typically used in HV, MV and LV radial networks as feeder or power transformer protection.
In solidly grounded systems the residual overcurrent protection can be used on feeders of any length, while in ungrounded or Petersen coil and/or resistance grounded systems, the residual overcurrent protection can be used on feeders of small length in order to avoid unwanted trippings due to the capacitive current contribution of the feeder on external ground fault.
Beside to the phase and residual overcurrent protection, the following protective functions are provided:
  • Thermal image protection of lines and power transformers
  • Undercurrent protection for monitoring of CB opening
  • Negative sequence protection against asymmetrical short circuits and unbalance loads
  • I2/I1 protection against phase interruption under low-load condition
  • Automatic reclosing.

FUNCTIONS


STANDARD PROTECTIVE & CONTROL ELEMENTS

  • Phase overcurrent side H and side L - 50/51
  • Maximum Residual Overcurrent - 50N/51N
  • Automatic Recloser - 79
  • Breaker Failure - BF
  • CT Supervision - 74CT
  • Trip Circuit Supervision - 74TCS
  • Under Current - 37
  • Negative sequence overcurrent - 46
  • Thermal Image Transformer - 49LT

SW PACK OPTIONAL CONFIGURATION

  • Thermal with Pt100 Probes - 26

COMMUNICATION FUNCTIONS

  • One USB Type B local port for communication with ThyVisor setup software

DOWNLOADS

NA21 Coding
Flyer NA21
PRON NA21 IEC 103 Attestation of Conformity
Manual NA21

RELATED PRODUCTS

XMR-A

XMR-A is a part of XMORE platform, the complete range of IEDs for Medium Voltage application including feeder, motor, generator, transformer and capacitor bank.

Thanks to Hardware and Software modularity XMR-A is flexible and scalable in term of application and performance as:

  • Overcurrent and Earth fault protection (StandardSW configuration)
  • Additional double Earth Fault input for two-side Transformer protection (SW PAC Xtra Current)
  • Additional Earth Fault Directional Overcurrent(SW PAC Xtra Voltage)
  • Small sized Motor Protection (SW PAC Motor)
The relay is compliant with CEI-016 requirements

...

> discover more

NA20

The relay type NA20 is typically used in HV, MV and LV radial networks as feeder or power transformer protection.
In solidly grounded systems the residual overcurrent protection can be used on feeders of any length, while in
ungrounded or Petersen coil and/or resistance grounded systems, the residual overcurrent protection can be
used on feeders of small length in order to avoid unwanted trippings due to the capacitive current contribution
of the feeder on external ground fault.
Beside to the phase and residual overcurrent protection, the following protective functions are provided:
  • Thermal image protection of lines and power transformers.
  • Undercurrent protection for monitoring of CB opening.
  • Negative sequence protection against asymmetrical short circuits and unbalance loads.
  • I2/I1 protection against phase interruption under low-load condition.

...

> discover more