VAC

An important safety function of differential current sensors is the monitoring of leakage currents against the earth of the entire system. Such systems consist of either a photovoltaic module or motor in combination with the inverter, or the grid in combination with a battery. A defective system can become dangerous for humans or cause fire, therefore corresponding standards require that the inverter or charger disconnects from the grid, before it might become dangerous for the system or humans.

Leakage currents are unintended hence uncontrollable fault currents against earth and can contain direct as well as alternating portions, therefore AC/DC-sensitive monitoring is necessary. The key component is the VAC differential current sensor, whose measurement value is transmitted as an output voltage and evaluated by the control system.

Generally, protection devices with AC/DC-sensitive differential current sensors shall be used, where flat or pulsating direct currents can occur, whose amount is permanently greater than zero. Further examples are power supplies or uninterruptible power supplies.