www.megger.com 7CAR CHARGERS FOR ELECTRIC VEHICLES:A STEP-BY-STEP GUIDE TO AUTOMATED TESTING 7WWW.MEGGER.COM ■ For testing L-PE circuits in chargers fitted with and RDC-DD (most chargers), select RDC EV or if a type B RCD is fitted select RCD on Hot Key 2. If testing L-N or L-L circuits, select NO RCD. ■ Press the TEST button. The MFT-X1 will display the loop impedance for the circuit being tested. If the correct mode is selected the RCD/RDC should not trip. ■If an internal RCD or RDC trips during the loop impedance test, the car charger output will be disabled. If the RCD in the supply to the charger trips the charger will switch off. If it’s an RCD, reset it. RDCs should reset automatically. The EVX will attempt to reset the charger by sending the state sequence C, B, A, B, C. It will continue to do this until the charger returns to State C2. ■Test the protection devices. Car chargers fitted with either a type B RCD, or a type A RCD and an RDC-DD, can be tested with the EVX. The EVX provides automatic test sequences for RCD and RDC testing, but if necessary, these can be modified in the SETTINGS RCD tab. Refer to the MFT-X1 user guide for more details. The test sequence is as follows: ■ Select the RCD test function on the left rotary knob of the MFT-X1. The charger should switch to State C2 and an output voltage should be indicated in the voltage widget on the MFT display. ■ Use Hotkey 2 to select EV A/B or EV A/RDC, depending on the devices protecting the EV charger. ■ Use Hotkey 5 to select L1-PE, L2-PE, L3-PE as required. ■ Press the TEST button. The MFT-X1 will start the test sequence testing the RCD at ½xI, 1xI and 5xI, followed by the RDC ramp test. ■ Each time the RCD trips, reset it. The EVX100 will automatically return the charger to State C2. RDCs will generally reset automatically. ■ At the end of the test sequence, the MFT-X1 will display the complete test sequence results. ■ After all devices have been reset, the EVX should return the charger to State C2. Note 1: RDC trip time can be up to 10seconds and is not generally recorded. However, the trip current (<6mA) is important. The RDC test, indicated with a ramp in the display, applies a current ramp test up to 6mA and holds that current for 10seconds. The RCD should trip between 3mA and 6mA. If it fails to trip in 10seconds the RDC has failed. Note2: In North America, RCDs are usually known as GFCIs (ground fault circuit interrupters) or, specifically when used in chargers, CCIDs (charge circuit interrupting device). Note 2: Some car chargers isolate all terminals when tripped, including the earth terminal. The voltage on the earth terminal may cause the MFT-X1 to show a PE error. If this happens, contact Megger technical services for further advice. ■After completing tests, ensure the car charger is reset, if necessary, and returned to normal operating mode. In particular, be sure to exit maintenance mode if this has been used, and to properly refit any covers that have been removed to gain access to, for example, protective devices.
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