Current Sensor (Residual Current Monitor)
Detect AC and DC leakage current in EV chargers and other mains equipment.
What is it?
A residual current monitor (RCM) watches the live and neutral conductors that run through it and measures the difference between the current going out and the current coming back. In a healthy circuit the two cancel. If current leaks to earth, for example through damaged insulation or a person, the difference appears as a residual current and the RCM flags it so the equipment can switch off. Magnias current sensors are RCM units for EV charging equipment: they detect both AC residual current and smooth DC residual current (6 mA DC), which EV charging standards require because the car side is DC.
When do you need it?
- Mode 3 EV chargers (wallboxes) that must detect 6 mA DC residual current (IEC 62955).
- Mode 2 in-cable control and protection devices (IC-CPD, IEC 62752).
- US Level 1 / Level 2 chargers that need a UL 2231 CCID20 charge-circuit interrupting device.
- Ground-fault and converter leakage-current detection.
How to pick the right one
- Standard and trip levels
- Match the outputs to your standard: 6 mA DC for IEC 62955, 20 mA for UL 2231 CCID20, 30 mA AC plus 6 mA DC for IC-CPDs (IEC 62752).
- Rated primary current
- The live and neutral conductors run through the sensor, so check its nominal current (Magnias: 40 A, 40 / 80 A or 42 A by part).
- Outputs
- Separate push-pull outputs for the DC and AC thresholds let the controller tell the fault type apart; a single output is simpler.
- Self-test
- Run the built-in function test at start-up or before each charge. No residual current may flow during the test.
- Insulation
- Check working voltage and insulation for your mains: the MRCM parts list 300 V rms working voltage, 3 kV AC test voltage and 7 kV impulse withstand.
- Supply
- 5 V (4.9-5.3 V), about 25 mA.
What Magnias offers
Four MRCM residual current monitoring units for EV charging equipment, all on a single 5 V supply with push-pull outputs and a self-check input: MRCM-M340-A6205P-A, MRCM-P280-A6205P-B and MRCM-N280-A6205P-C (6 mA DC and 20 mA rms outputs, IEC 62955 and UL 2231 CCID20, -40 to +85 °C) and MRCM-M342-A6305P-A (30 mA AC and 6 mA DC detection with one output, for IC-CPD designs, -40 to +105 °C). The sensor only monitors: your circuit must drive the relay, contactor or breaker.