Monitoring of return currents in railway networks

The Polaris performs a continuous monitoring of parallel connecting cables in 2 x 25 kV railway systems, which typically carry the return current. If the connection of one of these cables deteriorates, it will be detected and selectivelydisplayed. In addition, any undesired increase of the earth potential is detected and displayed.

The above events are remotely reported to the control room. This enables the railway asset management to send the service team to the point of failure in a targeted manner.

Equipment set includes:

  • 1 display unit
  • 2 – 6 single-phase current sensors
  • Monitoring of lines in the reverse current system of electrical railway supply
  • Monitoring the earth potential
  • Relay for remote signal

Technical specifications

Measurement sensors 0 - 630 A
tI>> response delay 500 ms / 1,000 ms / 5 s / 10 s (adjustable)
Threshold inequality 30, 40, 50, 60 % (adjustable)
Trip current earth potential 50 V AC -2 V/+2 V
Accuracy ±5 %
Amount of channels 2 - 6 (adjustable)

6 red LEDs / 1 per channel

2 yellow LEDs IMB> (unbalanced return current) and VE> (shift in earth potential)

1 red LED ERR (device error)

1 green LED PWR (power supply)

Relay contacts 2 relay contacts, momentary contact
Remote contact

Potential-free permanent contact

Contact capacity: 230 V AC/1 A/ 62.5 VA;

220 V DC/1 A/60 VA

Manual reset ---
Remote reset -
Automatic time reset -
Reset via interface -
Reset on current restoration -
Reset on voltage restoration -
Reset on restoration of auxiliary supply -
Reset via Explorer Software -
Internal power supply -
External auxiliary supply 24 V +10 %/-20 %, 200 mA max.
CT powered -


Temperature range -30 to +70 °C
Cable diameter -
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