Title www.megger.com6CAR CHARGERS FOR ELECTRIC VEHICLES:A STEP-BY-STEP GUIDE TO AUTOMATED TESTING6CAR CHARGERS FOR ELECTRIC VEHICLES: A STEP-BY-STEP GUIDE TO AUTOMATED TESTING WWW.MEGGER.COMWARNING: The following tests are live circuit tests. Appropriate procedures and precautions for live circuit testing must be observed at all times. ■Test PE and CP error mode. Make sure that the MFT is in voltage mode and that the MFT is displaying State C2. Then press Hotkey 2 to select CP error or PE error. The charger should be disabled and the MFT should show its output as 0 V. On releasing the Hotkey, the charger should return to State C2, and the voltage at its output should return to normal. The test should be repeated for both CP and PE errors. ■Test for PE earthing issues. Make sure that the MFT and EVX are connected and communicating. Switch the MFT-X1 to loop impedance mode and use Hotkey 5 to select the L-PE option. Check that the voltage widget triangle shows mains voltage (typically 230 V AC in the UK). Then touch, but DO NOT PRESS one of the red TEST buttons. If there is a problem with the PE bonding, the MFT will display a warning screen, and live testing will be inhibited. If no warning is displayed, it is safe to proceed with live testing. Note: The PE earthing test inhibit function can be disabled. See the EVX user guide for more information. ■The tests carried out so far have verified that the basic functions of the car charger are working correctly. The remaining tests are standard electrical tests that would be performed on almost any type of electrical installation. These tests should have already been performed up to the point of connection of the charger to the supply system, but they should now be repeated at the output of the charger. This is necessary because the charger may include additional protection devices, such as RCDs (GFCIs in the USA) and RDCs, which must be tested and will certainly include switching devices, such as contactors, that may add significantly to the total loop impedance. ■Before proceeding, determine the type of earth fault protection used with the car charger. In many cases, primary protection will be provided by a 30 mA type A RCD (residual current device) in the circuit supplying the charger, which works in conjunction with a 6 mA RDC-DD (residual direct current detecting device) within the charger. Alternatively, a 30 mA type B RCD, either within or outside the charger, may be used on its own, without an RDC-DD. All of the earth fault protection devices will need to be tested to verify correct operation. The type of device(s) fitted will affect the type of tests used. ■Measure loop impedance. Loop impedance is measured in the same way as it would be on the MFT-X1 without the EVX adaptor, but note that the EVX limits the functionality of the MFT-X1 to those tests appropriate for use on EV chargers. The outline test sequence is as follows. For further details, refer to the MFT-X1 user guide. ■ Select the loop test function on the left rotary knob of the MFT-X1. The charger should switch to State C2, and output voltage should be indicated in the voltage widget on the MFT display. ■ Press Hotkey 1 to select Z. ■ Press Hotkey 5 to select the circuit connection you wish to test: - For chargers rated 7 kW or less, select L1-PE, or L1-N. - For chargers rated more than 7 kW, use Hotkey 5 to select L1-PE, L2-PE or L3-PE for earth loop impedance testing, or L1-N, L2-N or L3-N for Live to Neutral testing. ■ In addition, on 3 phase chargers you can select L1-L2, L2-L3 or L1-L3 for multi-phase testing. Press Hotkey 4 to select either 3 wire or 2 wire testing. - For L-PE tests ALWAYS use the 3 Wire option. For All other tests use the 2 Wire option.
Previous page: Steg-för-steg-guide för automatiserad testning av [5 / 8]
Next page: Steg-för-steg-guide för automatiserad testning av [7 / 8]
