Stator earth fault protection for Generators by Low-Frequency/ 20Hz Injection method

Stator earth fault protection for Generators by Low-Frequency/ 20Hz Injection method

The 100% stator earth fault protection system is based on a sub-harmonic injection principle. To implement a 100 % stator earth fault protection system a 20Hz current is injected into the generator star point. The 20Hz generator SGEN-1001 is used in combination with the Band Pass Filter SBPF-1001 in the Stator Earth fault protection. The injection can be performed by connecting the SGEN-1001 and the SBPF-1001 to the load resistor of an earthing or neutral transformer. If an earth fault occurs in the generator star point, the 20Hz current flows through the fault resistance. From the driving voltage and the fault current, the protective relay determines the fault resistance.

Features

  • 100 % stator earth fault protection based on subharmonic injection
  • Detectsstator earth faults when the generator is offline
  • Provides a wide range of fault resistance coverage
  • Low-cost unit with high performance
  • Plug and Play System

Applications

  • Generators

Specifications

20Hz GENERATOR SPECIFICATION

Power Supply
Supply Voltage 85 to 260V AC, 1φ, (47Hz to 63Hz)
or 120V to 370V DC
System Status
LED Power & Signal
Alarm PFC contact
Output Signal
Output Voltage 50V Peak to peak +10%, Rectangular
Output Current 5A continuously
Output Frequency 20Hz +5%
Efficiency 85%
Environment
Operating Temp 0°to 55°C
Humidity 93% Non-Condensing
Cooling Passively Cooled
Mechanical
Dimension 482mm x 173mm x 245mm +5mm
Enclosure Panel/Table Top Mountable
Protection Class IP20
Test
Burn-in Test IEC 60068-2-78
Vibration Test IEC 60068-2-6
Shock Test IEC 60068-2-27
Seismic Test IEC 60068-3-3

 

20Hz BANDPASS FILTER SPECIFICATION

Input Signal
Frequency 20Hz +5%
Voltage 50V +10%, Rectangular
Output Signal
Output Voltage Min 25V RMS without Load
Output Current 5A continuously
Output Frequency 20Hz +5%
Withstand voltage 245V AC at 50Hz (NGT V)
The impedance at the centre frequency <5Ω @ 20Hz
The impedance at System frequency >50Ω @ 50Hz
Environment
Operating Temp 0°to 55°C
Humidity 93% Non-Condensing
Cooling Passively Cooled
Mechanical
Dimension 482mm x 173mm x 245mm +5mm
Enclosure Panel/Table Top Mountable
Protection Class IP20
Test
Burn-in Test IEC 60068-2-78
Vibration Test IEC 60068-2-6
Shock Test IEC 60068-2-27
Seismic Test IEC 60068-3-3

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