[Summary]As the electric vehicle industry continues to expand, the frequency and scope of using electric vehicle charging facilities will increase. According to data from the China Association of Automobile Manufacturers, in the first half of 2022, China's new energy vehicle production and sales reached 2.661 million and 2.6 million respectively, both growing by 1.2 times year-on-year, with a market penetration rate of 21.6%. Therefore, the safety issue of electric vehicles cannot be overlooked and should be integrated into every stage of the charging process to ensure the safety of the charging personnel, facilities, and process.
[Keywords]Electric Vehicles; Charging; Safety
0. Overview
In recent years, the electric vehicle and its supporting charging infrastructure industry has experienced a period of rapid development, but the economic returns remain less than optimistic. The supply chain of electric vehicle charging systems and their equipment involves various stakeholders, including operators, equipment manufacturers, car manufacturers, and connector manufacturers. Establishing a safe management system for charging facilities requires a significant investment of human, material, and financial resources, further increasing the pressure on all involved enterprises. Considering this, many charging equipment companies and product manufacturers within the industry have resorted to reducing component costs and工艺 standards to lower selling prices in exchange for wider sales and deployment rates. The domestic market is characterized by a mix of good and bad, and the industry faces multiple issues such as a lack of unified standards and high certification difficulties.
Analysis of Safety Risks in Electric Vehicle Charging Products
In response to several safety incidents involving electric vehicle charging facilities, particularly the commonly used AC charging stations, that have caused fires and burns, an analysis of the risk sources has been conducted. Besides safety risks arising from improper system and equipment installation or inadequate maintenance, the main risk points involving product quality issues include the following aspects:
(1) Electrical Risk: ① Defects in electrical shock protection lead to excessive contact current, with common issues including overly small protective grounding conductor specifications and excessively large protective grounding connection resistances. ② Lack of residual current protectors, or inappropriate selection of the protector type, means that the product cannot effectively and promptly cut off power in the event of equipment failure or insulation degradation, increasing the risk of electric shock accidents. ③ The continuous monitoring function for the protective grounding conductor is missing in some products, with issues such as rusted and loose screws at the grounding connection points or abnormal grounding conductor open circuits. Although the product can still operate normally, if a leakage fault occurs, the product's housing and metallic parts may become electrified, posing an electric shock hazard. ④ The equipment lacks insulation detection and grounding continuity detection functions.
(2) Short Circuit Risks: ① Insulation resistance is low, leading to reduced insulation performance, which may cause phase-to-ground short circuits or equipment-to-ground short circuits, posing fire hazards in severe cases. ② Failure of overcurrent protection can easily result in overheating of the charging circuit, even leading to burn damage of the output cable's insulation, presenting a short circuit risk.
(3) Fire Risk: ① The overload protection device specifications are oversized. If the charging demand exceeds the rated output current and charging power, and the overload protection device's action limit is not triggered, the entire charging circuit, including the charging cable and connection points, will be at risk of overheating, potentially leading to a fire. It will not serve as a protective measure. ② Both power supply and vehicle connectors should be equipped with necessary temperature monitoring devices. Both the power supply equipment and the electric vehicle systems should be equipped with functions to monitor temperature and provide over-temperature protection.
(4) Comprehensive Risks: ① The protective grade (IP) of the housing is below the standard requirements (e.g., indoor IP32, outdoor IP54), particularly in outdoor applications. Since the product fails to meet the IP54 requirements, exposure to sunlight and rain can lead to phenomena such as water intrusion, rust, and dust accumulation inside the components, potentially causing a decrease in electrical shock protection and insulation performance, ultimately resulting in safety risks such as leakage and short circuits. ② Contactor粘连 can lead to uncontrolled machine operation, and in severe cases, may cause mechanical accidents or personal injuries. ③ Vehicle connectors without an electronic locking device or a failed locking device can result in unavoidable live disconnections during charging, posing a risk of electric shock to the user. Additionally, direct current (DC) charging machines may experience arcing, leading to fire hazards. ④ Failure of the emergency stop button can damage equipment and even cause personal injury accidents. ⑤ Communication failures can prevent the charging machine from stopping charging in a timely manner, potentially damaging the equipment or causing personal injury.
(5) Other Risks: During the startup of the charging process, excessive surge currents may cause disturbances from instantaneous current spikes, leading to abnormal equipment operation and circuit damage.
2. Electric Vehicle Charging Protection Measures
Adding an electrical fire prevention current limiting protector at the front end of electric vehicle charging piles is one of the important protective measures. In the event of a short circuit fault in the protector's rear-end circuit, the system's current surges, and the protector can complete current limiting protection within 150 microseconds, preventing electrical fires from occurring at the protector's rear end. Secondly, the current limiting protector can enable residual current monitoring, monitoring the residual current value at the rear end. When the residual current exceeds the set value, the protector can either activate current limiting protection or trigger an alarm. Thirdly, the current limiting protector can enable overload and cable temperature monitoring. When the system is overloaded or the cable temperature is too high, the protector can either initiate current limiting protection or raise an alarm.
3. Product Overview
Electrical fire-limiting current protectors effectively overcome the drawbacks of traditional circuit breakers, air switches, and monitoring equipment, such as large short-circuit currents, long time to interrupt short-circuit currents, large arcs and sparks generated during short-circuit, and short service life. In the event of a short-circuit fault, they can rapidly limit the short-circuit current at a microsecond speed to achieve arc extinguishing protection, thereby significantly reducing electrical fire accidents and ensuring the safety of personnel and property in the usage area.
The ASCP300-63B Electrical Fire-Resistant Current-Limiting Protector is a three-phase current-limiting protector with a maximum rated current of 63A. It is widely applicable for line protection in various electrical locations, such as schools, hospitals, shopping malls, hotels, entertainment venues, temples, cultural heritage buildings, exhibitions, residential areas, warehouses, kindergartens, elderly buildings, collective dormitories, electric vehicle charging stations, rental commercial shops, wholesale markets, and marketplaces, as well as for the main and branch circuits in various power supply facilities.
(1) Features and Benefits
Short-circuit Protection Feature. The protector monitors the current in the electrical circuit in real-time and can achieve rapid current limiting protection within 150 microseconds when a short-circuit fault occurs, accompanied by an audible and visual alarm signal.
Overload Protection Feature. When the protected circuit experiences an overload and the overload duration exceeds the set trip time (adjustable from 3 to 60 seconds), the protector activates current limiting protection and emits an audible and visual alarm signal.
Over-temperature Protection Function. When the internal components of the protector exceed the operating temperature, the protector initiates over-temperature current limiting protection and emits an audible and visual alarm signal.
Overvoltage and undervoltage protection function. When the protector detects line voltage being either too low or too high, it emits an audible and visual alarm signal, and it can be pre-set to activate current limiting protection.
Temperature Monitoring Function for Power Cable. When the monitored cable temperature exceeds the alarm setpoint, the protector emits an audible and visual alarm signal, and it can be pre-set to activate current limiting protection.
Phase Loss Protection Function. Upon detection of a phase loss in the circuit, the protector triggers an audible and visual alarm signal, initiating a current limiting protection.
Leakage Current Monitoring Function. When the monitored circuit exceeds the alarm setting value, the protector emits an audible and visual alarm signal, and it can be pre-set to initiate current limiting protection.
The protector features a 1-way RS485 interface, allowing data to be transmitted to the back-end monitoring system for remote surveillance. The monitoring backend can be an Acrel-6000/B electrical fire monitoring host by AnkoRui, an Acrel-6000 safe electricity usage management cloud platform by AnkoRui, or a third-party monitoring software or platform.
(2) Application Case
(3) Product Aesthetics
4. Conclusion
The ASCP series electrical fire protection current-limiting devices are specifically designed by Ankorui to protect low-voltage distribution lines from issues like short circuits and overloads. They effectively overcome the drawbacks of traditional circuit breakers, air switches, and monitoring equipment, such as high short-circuit currents, long time for cutting off short-circuit currents, large arcs and sparks during a short circuit, and short service life. In the event of a short-circuit fault, they can rapidly limit the short-circuit current at the speed of microseconds to achieve arc extinction protection, significantly reducing electrical fire accidents and ensuring the safety of personnel and property in the usage location.
