Title www.megger.com4CAR CHARGERS FOR ELECTRIC VEHICLES:A STEP-BY-STEP GUIDE TO AUTOMATED TESTING4CAR CHARGERS FOR ELECTRIC VEHICLES: A STEP-BY-STEP GUIDE TO AUTOMATED TESTING WWW.MEGGER.COMCar charger control signalsTwo control signals – proximity pilot (PP) and control pilot (CP) - are used to communicate between the vehicle and the car charger. These are set on the adaptor or if using the EVX, automatically by the instrument.The PP signal indicates to the car charger that a vehicle is connected. One of its primary functions is to ensure that the EV does not drive off while charging is in progress. The PP signal is also used to indicate the maximum charging rate applicable to a particular combination of car charger and EV. Car charger testers need to be able to simulate PP signals.The CP signal provides information about the status of the charging process, and for the purposes of testing a car charger, the test equipment needs to simulate these CP states: ■State A – no vehicle connected ■State B – vehicle connected but not ready to charge ■State C – vehicle connected and ready to charge; ventilation not requiredOptionally the test equipment may also provide: ■State D – vehicle connected and ready to charge; ventilation requiredEquipment for testing car chargersThe equipment needed for testing all car chargers (except for Mode 4 types) can be divided into two sections. First, an electrical test instrument, such as an electrical installation multi-function tester (MFT), is required. This is the same type of instrument used for general testing on electrical installations, including the supply to the car charger, but it needs to have some extra features to test the unique protective devices often used in car chargers. Second, a car charger adaptor is needed, which must mimic a vehicle’s connection to the charger. The adaptor may also offer basic safety tests, such as checking for earthing issues and simulating basic error conditions of the Control Pilot (CP) and Proximity Pilot (PP) signals, which are explained in more detail later.In the case of the EVX adaptor used with the MFT-X1 multifunction installation tester, the adaptor mounts directly onto the tester with a single lead to the car charger – no additional interconnecting cables are required. The standard type adaptor such as the EVCA210 is connected to the charging outlet of the car charger using a suitable type of supplied connector, and the adaptor connects to the test instrument using the instrument’s standard test leads.Alternatively, a self-contained and simplified car charger checker can be used to verify the functionality and basic safety of a car charger. However, these checkers do not offer the full range of functionality of the MFT and adaptor. Consequently, they are unsuitable for initial verification of a newly installed car charger, but they are ideal for post-installation testing and maintenance. A separate step-by-step guide covering the use of this kind of checker is available. The remainder of this document assumes that tests are being carried out using a Megger MFT-X1 multifunction installation tester plus an EVX car charger adaptor.Testing step-by-stepAn important note about resetting chargersSome of the tests described will make the charger trip out because of simulated fault conditions, while others will necessarily cause protective devices to trip. Before proceeding, check carefully that it will be possible to reset the charger or protective device after tripping. Chargers used in non-domestic applications are frequently networked, and supervisor-level access to the network may be needed to reset them. In some cases, however, the charger may offer a maintenance mode to permit local resetting during testing. If this mode is available, it should be used. It is also recommended that in new installations electrical testing should be completed, if possible, before connecting chargers to the network. A further issue relates to protective devices. These are often external to the charger and may even be in another building. It is, therefore, important to know the location of the devices and to be sure that access is available to reset them.
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