Results of all four tests are displayed in trip current. Again, a 0° or 180° option is available.
The tests are performed in the same manner as shown above for the fundamental protective device test. Output voltage, touch voltage and the chosen earth leakage current test are performed, as previously described. The result is displayed in mA. Interpretation of results is similar to that for the fundamental GFCI/ RCD performance tests.
Charger Operation Checking Tests
3.1 Proximity Pilot (PP) check: A proximity circuit provides the electric vehicle with a signal so that it knows it is connected to a charger. The proximity circuit prevents the vehicle from moving. When not connected, the voltage on the proximity pin of the electric vehicle is 4.5 V. Once connected, the voltage drops to 1.5V. A charger tester will check to as- sure that this happens correctly by simulating the circuit in the electric vehicle. In chargers that use separate connecting charging cables, the connector applies a PP resistance signal to the charger to indicate to the charger the rating of the connection cable being used. The maximum current available indicated to the vehicle via the CP signal is adjusted accordingly. A charger tester is used to check that this happens correctly by testing with different rated connecting cables.
3.2 Control Pilot (CP) check: The control pilot signal is the communication between the charger and the vehicle. There are three main areas of communication: state of the vehicle/charger, max current to be drawn by the vehicle and whether digital communication indicates current.
The state of the vehicle/charger comprises disconnected, connected, charging, charging with ventilation, CP to PE fault, and charger fault. The Control Pilot signal is a 1 kHz square wave signal with the charger state communicated using the signal voltage level. Max current and digital communication use are indicated by the signal duty cycle. The charger tester takes the place of the vehicle and allows the user to set the CP code. The tester then reads the code back from the charger as set out in Table 8 of the IEC Standard 61851-1. This allows the user to verify the correct operation of the charger, ensuring that the charger responded as expected. Also, testing the Control Pilot signal measures the charger output voltage and frequency.
Output charging voltage and frequency should be as expected for the supply to which the charger is connected. Polarity should read ok. The max current should match the rating of the charger or connecting cable. Control pilot voltage, duty cycle and frequency should be repeatable. The CP state read from the charger should match the code set for the test. A fault or error with the charger itself will be indicated.
A Preventive Maintenance program is just as much in order for electric vehicle chargers as for any other piece of electrical equipment. Don’t let their apparent simplicity or ubiquity create a false sense of security or complacence. There are potential safety hazards that are readily identified and corrected, with an appropriate Electric Vehicle Charger Tester in regular use as part of an electrical maintenance program. These tests can be performed quickly and readily, creating a valuable asset against equipment damage and personnel injury along with a list of other benefits that include client and customer protection, Standards compliance, and legal safeguards.
