DC-Current Monitor – Type 8546-RVL



The 8546-RVL current monitor works with 24V DV and measures the magnetic field around a conductor (e.g. a power rail).

The 8546-RVL is designed to monitor a railways voltage limiter (RVL). A program specially adapted for the RVL serves to monitor it and to provide error reports.
The polarity of the DC-current does not affect this.

Special technology means that the device remains functional even with strong magnetic fields (e.g. lightning strikes), despite its high responsiveness. The switching threshold of the device (sensitivity) can be set with a potentiometer. If the switching threshold is exceeded by the current, a digital switching output (positive switching around 24V DC) is triggered.

As a basic principle, the device operates with a storing output (latch), i.e. exceeding the threshold once leads to permanent setting of the output. The device is reset by means of a 24V DC reset input. If this input is connected permanently to 24V DC, the latch function is suspended and the output of the device follows the measurement current.

A test button allows the sensitivity of the device to be increased by a factor of 3. This can be used for adjustment to a current that is smaller by this factor.
The operation of the switch output is „low active“, i.e. if the device has not exceeded its threshold value, the output is at 24V DC. If the threshold value is exceeded, the output is drawn towards GND. A line break in the downstream analysis is therefore treated in exactly the same way as an overcurrent.

The status of the device is shown by two LEDs:

  • green LED: ready for operation
  • yellow LED: check RVL

The output is set if the pre-set current is exceeded three times within 60 mins. or if the pre-set current flows for longer than 60 mins.

The output is automatically reset after 8 hours or by means of a reset pulse applied to input (2).

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