The relay type NA90 can be typically used in radial or meshed MV and LV networks as feeder or power transformer protection:
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On radial, ring and parallel feeders of any length in solidly grounded, ungrounded, Petersen coil and/or resistance grounded systems.
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On parallel connected generators and transformer on the same busbar.
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For ground fault protection on both sides of power MV-LV transformers.
Moreover undervoltage and overvoltage functions are provided.
Specifications
Key: 
standard 
optional 
alternative
Applications
- Feeder
- Generator
- Motor
- Transformer
Protection functions
- Pt100 thermometric probes (26)
- Undervoltage (27)
- Thermal image (49)
- Phase overcurrent (50/51)
- Measured residual overcurrent (50N(1)/51N(1))
- Measured residual overcurrent (50N(2)/51N(2))
- Calculated residual overcurrent (50N(Calc)/51N(Calc))
- Overvoltage (59)
- Residual overvoltage (59N)
- Phase directional overcurrent (67)
- Ground directional overcurrent (67N)
- High impedance restricted earth fault (87NHIZ)
- Breaker failure (BF)
Monitoring and control functions
- CB diagnostic
- Cold Load Pickup (CLP)
- CTs monitoring (74CT)
- Digital Fault recording (DFR)
- Fault and event logging (SER & SFR)
- Logic selectivity
- Multiple setting profiles
- Programmable Logic Controller
- Second harmonic restraint
- Self-test
- Trip circuit supervision (74TCS)
- VTs monitoring (74VT)
Hardware
- 2 binary inputs + 6 output relays + 8 LEDs
- Auxiliary power supply 110-230 Vac/dc
- Auxiliary power supply 24-48 Vac/dc
- Flush, projecting, projecting, rack, with separate MMI
- Network module with Ethernet FX port (optical fiber)
- Network module with Ethernet TX port (copper RJ45) + RS485 port
- Nominal current 1/5 A selectable by DIP-switch
- RS485 port (unavailable with Ethernet FX port)
- Standard CT amperometric inputs 1/5 A
Communication
- Modbus RTU RS232 protocol
- Modbus RTU RS485 / IEC 870-5-103 / DNP3 protocol
- Modbus TCP/IP protocol (network board must be provided)