Abstract: AC charging pile, commonly known as "slow charging pile", is fixedly installed outside the electric vehicle and connected to the AC grid. The national standard adopts 220V single-phase alternating current on the power supply device that provides AC power on-board chargers for electric vehicles (that is, the chargers that fixedly installed on electric vehicles). The national standard GB51348-2019 stipulates that it should be equipped with current-limiting electrical fire protection devices in the places for reserve warehouses, electric vehicle charging and so on. Electrical fire-resistant current-limiting protectors can effectively overcome the disadvantages such as high current during short-circuit, long time to cut off short-circuit current, large arc sparks generated during short-circuit, and short service life of the traditional circuit breakers like air switches and monitoring equipments.When a short-circuit fault occurs,it can quickly limit the short-circuit current at a microsecond speed to achieve arc extinguishing protection, which can significantly reduce electrical fire accidents and ensure the safety of personnel and property on site.

Keywords: electric vehicle charging pile; AC charging pile; charging pile distribution box; slow charging pile; short-circuit protection; electrical fire protection

0.Industry background

    With the development of the world, environmental protection has become the task of the human community with a shared future. Because new energy vehicles have no exhaust emissions, no harmful substances such as carbon monoxide, carbon dioxide, nitrogen oxides, no noise pollution, and less environmental pollution, governments around the world also provide preferential policies to encourage the popularization of electric vehicle technology.

    AC charging pile, commonly known as "slow charging pile", is fixedly installed outside the electric vehicle and connected to the AC grid. The national standard adopts 220V single-phase alternating current on the power supply device that provides AC power on-board chargers for electric vehicles (that is, the chargers that fixedly installed on electric vehicles). The AC charging pile only provides power output and has no charging function. It needs to be connected to the on-board charger to charge the electric vehicle, which only plays the role of controlling the power source. It adopts an AC charging mode that conforms to the national standard, and the output power is not higher than 7kW. Generally, it takes 5-8 hours for a vehicle battery to be fully charged from 0. The specific situation depends on the capacity of the power battery of different models and the actual charging power.

    For electric vehicle charging piles, the national standard GB51348-2019 《Civil Building Electrical Design Standards》13.5.5 stipulates that it should be equipped with current-limiting electrical fire protection devices in the places for reserve warehouses, electric vehicle charging and so on.

1.Product introduction

     The ASCP series of electrical fire-resistant current-limiting protectors are specially developed by Acrel to protect short-circuit and overload problems in low-voltage power distribution lines. It can effectively overcome the disadvantages such as high current during short-circuit, long time to cut off short-circuit current, large arc sparks generated during short-circuit, and short service life of the traditional circuit breakers like air switches and monitoring equipments. When a short-circuit fault occurs,it can quickly limit the short-circuit current at a microsecond speed to achieve arc extinguishing protection, which can significantly reduce electrical fire accidents and ensure the safety of personnel and property on site.

The ASCP series of electrical fire protection current-limiting protectors can be widely used in the protection of main and branch line in various places where electricity is used,such as schools, hospitals, shopping malls, hotels, entertainment venues, temples, cultural relics, libraries, archives, exhibitions, residences, warehouses, kindergartens, elderly buildings, dormitories, Electric vehicle charging stations and leased-for-sale shopping malls, wholesale markets, bazaars, dangerous goods warehouses for Class A, B, and C, and so on.

For the case of using a centralized distribution box in an electric vehicle charging station, it is recommended to use the ASCP500-40B series of multi-circuit current-limiting protective boxes. It not only simplifies the installation, but also can be more beautiful and practical. The product is showed below.

1）The function of Short-circuit protection. The protector monitors the current of 4/6 power lines in real time. When a short-circuit fault occurs, it can achieve rapid current-limiting protection within 150 microseconds and send out sound and light alarm signal.

2）The function of overload protection. When the current of the protected circuit is overloaded and the duration of the overload exceeds the action time (3~60 seconds can be set), the protector will start the current-limiting protection and send out sound and light alarm signal.

3）The function of over-temperature protection in the meter. When the operating temperature of the internal components of the protector is too high, the protector implements over-temperature and current-limiting protection and sends out sound and light alarm signal.
4）The function of Over-voltage protection. When the protector detects undervoltage or overvoltage of the line voltage, the protector sends out sound and light alarm signal, and it can be set in advance whether to activate current-limiting protection.
5） The function of leakage current monitoring. When the monitored line leakage exceeds the alarm setting value, the protector will send out sound and light alarm signal，and it can be set in advance whether to activate current limiting protection.
6）The protector display unit has a RS485 interface, which can be connected to a wireless communication module, supports 2G, NB-IoT and 4G, and can send data to the background monitoring system to realize remote monitoring. The monitoring background not only can be the host for electrical fire monitoring of Acrel Acrel-6000/B ,but also can be the safe cloud platform for power management of Ankerui Acrel-6000, even can be a third-party monitoring software or platform.

3.Product application

For AC charging piles, centralized power supply is generally used. If it is installed outdoor, the charging piles are distributed in multiple locations, and the positions are relatively scattered. It’s trouble to install electrical fire-resistant current-limiting protector on every charging pile,and also,there is no installation location and the requirement of waterproof is really high.. If it is installed on the wall indoor, the protector needs a certain position.However, the unified and centralized installation way is convenient to manage and maintain.

Indoor parking lot, the charging pile is wall-mounted

Outdoor parking lot, using columns to install dispersedly

    The distribution box of the charging pile is generally installed in a centralized manner during the design, as shown in the following figure.

    Therefore, it can be installed on the wall in batches according to the design drawings.