With the Indian government push for Electric vehicles by imposing aggressive implementation goals for the next few decades, electric vehicle infrastructure development becomes prominence and ought to be realized in parallel as the EV market grows over years. By “ Electric vehicle infrastructure “, I mean the well-connected EV charging network around the country. The government also wants to install charging stations in around 60,000 state-run and private petrol stations around the country which will improve the drive connectivity nationally.
There are various kinds of EV charging systems which are used in Home charging for usage less than 2.5kw as well as public charging. Chargers are classified into AC and DC chargers based on the type of power fed to the vehicle onboard charger. Another type of classification of chargers is fast charging stations and slow charging stations. The main advantage of the development of Charging infrastructure is to achieve an extended range for an electric vehicle while on road. The Central Electricity Authority released safety guidelines and provisions to be followed while setting up an EV charging station. These provisions apply to AC and DC charging Points with standard A.C. supply voltages and D.C. supply voltages for providing power supply to Electric Vehicle (EV). This article emphasises the key points in the safety guidelines.
Important bullet points of this document are follows
- All EV charging stations shall be installed so that any socket-outlet of supply is at least 800 mm above the finished ground level.
- Cable assembly shall be constructed so that it cannot be used as extension set while connecting EV to the charging point.
- Adaptors shall not be used to connect a vehicle connector to a vehicle inlet.
- Parking places specific to EVs should be such a way that the connection on the vehicle parked shall be within 5 meters from the EV charging point.
- Portable socket-outlets are not permitted to be used for EV charging.
- Suitable lightning protection system shall be provided for the EVs charging stations as per IS/IEC 62305. The standard classifies the sources and types of damage to be evaluated and introduces the risks or type of losses to be anticipated as a result of lightning activity.
- The Charging stations shall be equipped with protective devices against the uncontrolled reverse power flow from the vehicle.
- While disconnection, after one sec, the voltage between accessible conductive parts or between earth shall be less than or equal to 42.4 Peak ( 30 Vrms ) or 60V DC. If the voltage is greater than 42.4 V peak (30 V RMS) or 60 V D.C., or the energy is 20 J or more, a warning label shall be attached in an appropriate position on the charging stations.
- A vehicle connector used for D.C. charging shall be locked on a vehicle inlet if the voltage is higher than 60 V D.C. The vehicle connector shall not be unlocked (if the locking mechanism is engaged) when hazardous voltage is detected through the charging process including after the end of charging. In case of a charging system malfunction, a means for safe disconnection may be provided.
- The D.C. EV charging point shall disconnect the supply of electricity to prevent overvoltage at the battery if the output voltage exceeds the maximum voltage limit sent by the vehicle. This enables the charging station to get disconnected when an overvoltage is seen at the supply end and charging should not happen. An indication of this error on the panel will be a value-adding feature.
- The EV Charging station shall not energize the charging cable when the vehicle connector is unlocked. The voltage at which the vehicle connector unlocks shall be lower than 60 V. The residual voltage during unlocking may lead to sparking and this norm make sure no sparks or low-level sparks if the voltage is less than 60V.
- Earthing of all EV charging stations shall be TN system as per IS 732. IS 732 is an Indian standard code for electrical wiring installations for various voltage levels.
- The enclosure of charging stations shall be made of fire retardant material with self-extinguishing property and free from Halogen. A fire retardant is a substance that is used to slow or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion.
- An electric vehicle charging station operator shall arrange periodic test/ inspection of an EV charging station or EVSE should be carried out by electrical inspector/CESE in every four years. The owner/operator shall keep records of the results of every periodic assessment and details of any issues found during the assessment; and any actions required to be taken in relation to those issues. The owner/operator shall retain a copy of all records, whether in hard copy or electronically, for at least seven years and shall provide a copy of the records to the inspecting officers.
- The owner/operator shall establish and implement a safety assessment programme for regularly assessing the electrical safety of EVSE, conductors and fittings.
- Where the connection point is installed outdoors, or in a damp location, the equipment shall have a degree of protection of at least IPX4 in accordance with IEC 60529. IPX4 is resistant to water splashes from any direction. This is a critical requirement as the charging stations will be installed outside.
My take on this regulation is as follows that
- All the major points have been taken care in terms of safety to the end user while charging.
- Most of the points above are related to design level implementation, some are to take care while installation and a few points to be taken care during the charging system lifetime.
- Regarding the point “ The Charging stations shall be equipped with protective devices against the uncontrolled reverse power flow from the vehicle “, is opposing the entire concept of Vehicle to Grid configuration. I think this should be defined better to make sure the vehicle to the grid also can be realized.
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