Monitoring relays

The latest-generation PMDsigma relays monitor voltage, current, temperature and phase sequence, while enabling values to be set via a rotary knob and saved onto a chip card so they can be copied onto other units.

The unit indicates motor load, monitoring the thresholds and simultaneously providing an analog voltage or current value proportional to the true power, so the overload and underload thresholds can be monitored via an analog signal (PLC) or relay.

Both DC and AC motors rated up to 550 V and 11 kW along with frequency-controlled drives can be monitored directly, while larger motors can be monitored via current transformers.

Motor start-up and transient power fluctuations can be suppressed so that high inrush currents don’t affect the unit.

An early warning system for hazardous plant conditions can be implemented without needing additional sensors.

Filter plugging or wear and tear on mechanical components such as bearings can be identified before they lead to failure.