LEM presents new leakage current transformer for electric vehicle charging stations

The CDSR 0.07-TP/NP was developed by LEM to meet the market demand for residential and commercial charging stations and is available as a version for single-phase architectures (TP) as well as for three-phase systems (NP).

Since 2016, IEC standards have required that DC leakage currents of 6mA must be detected. This prevents the residual current circuit breakers in the domestic installation from becoming ineffective. This phenomenon, known as the "blinding effect", occurs when an electric vehicle (EV) has an insulation fault.

Following the trend towards digital technology, the CDSR has an analog output as well as a Serial Peripheral Interface (SPI), which makes it easy to connect the hardware. The CDSR is operated with +3.3VDC and has a typ. It has a typical current consumption of only 50mA when measuring a maximum of 150mA primary fault current. 

The ratiometric behavior of the CDSR ensures that fluctuations in the power supply are compensated and a stable output signal is guaranteed. This has a typical response time of less than 200us and, together with the independent test winding available for functional testing of the EV charging station in real time, offers a high degree of safety.

The CDSR is extremely robust and is suitable for operation in all EV charging stations from 3.7 to 22kW (max. current per phase 32Aeff). It works in an operating temperature range of -40 to +85°C and its long air and creepage distances of 13.2 mm ensure very high insulation between the primary and measuring circuits.

The CDSR is an essential part of vehicle electrification and will make the charging infrastructure more affordable, safer and more reliable in the future. Developed by LEM's R&D team in Geneva, it offers new opportunities to reduce CO2 emissions through DC charging systems.

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