Insulation monitoring for DC charging stations

The number of electric vehicles is constantly increasing and will grow even faster in the future. This will also drive forward the expansion of the charging station infrastructure, as DC charging stations are the first choice when electric vehicles need to be charged in the shortest possible time. Electrical safety must be guaranteed during the charging process. For this purpose, an unearthed DC power supply system (IT-grid) with insulation monitoring is set up and monitored by means of an insulation monitoring device (IMD). The user must never be exposed to high voltages (up to 1000 V) at any time.

The insulation monitor RN 5897/020 of the VARIMETER IMD family is used especially for DC charging stations according to the IEC/EN 61851-23:2014/AC:2016-06 standard and monitors the charging process from the charging station into the vehicle. The device is characterised by the short response delay of ≤ 1s, a rated voltage up to DC 1000 V with coupling device and the detection of asymmetrical as well as symmetrical insulation faults. The integrated voltage measurement ensures reliable detection of the insulation resistance in the IT grid. The insulation monitor also features a selftest. This takes place automatically after power-on and after every full operating hour.