AC/DC sensitive residual current monitor for electric vehicle charging systems

The AC/DC sensitive residual current monitoring module RCMB420EC is used for fault current monitoring of AC charging stations for electric vehicles, in which DC or AC fault currents are likely to occur, the value of which is constantly greater than zero.

Residual current monitoring of the charging station takes place via an externally connected measuring current transformer. Here, the r.m.s. value is determined by the DC component contained in the residual current and the AC component that is below the cut-off frequency.

The alarm relays switch when the limit values IΔn ≥ 6 mA DC and/or r.m.s. value IΔn ≥ 30 mA (r.m.s.) are exceeded.

After actuation of the device's own test button or via the digital input (e.g. with an external test button or a control device), the device generates a test current. The level of the test current is designed so that when functioning correctly the threshold is exceeded triggering both alarm relays.

Device features

• DC sensor acc. to IEC 60364-7-722 (VDE0100-722) with additional AC tripping (type B characteristic)
• Response value 1: DC 6 mA
• Response value 2 – AC/DC 30 mA: r.m.s. value measurement
• Frequency range residual current 0…2000 Hz
• Frequency range load current 45…65 Hz
• Monitoring of the connection to the measuring current transformer
• Fully shielded residual current transformer to avoid influences due to external disturbances

Variants: One-channel (RCMB422EC) and two-channel (RCMB420EC) residual current measurement