Residual Current Monitoring

The monitoring of residual currents is also called Residual Current Monitoring (RCM). It is used to detect residual currents and to signal changes. This makes it possible, for example, to detect residual currents even below critical limit values and before the supply line is switched off, and to take appropriate measures such as replacing the defective device.

The systems for detecting residual currents are divided into different types depending on the type of residual current. These are essentially:

Type A

This type of residual current involves pure sinusoidal alternating currents or pulsating direct currents. Most residual current protection systems detect type A residual currents. E.g. residual current circuit breakers.

Type F

In addition to type A residual currents, this type detects any AC currents up to 1 kHz.

Type B

This type detects the currents of type F and additionally also smooth DC currents.

Type B+

This residual current protection system corresponds to type B with detection of currents with frequencies up to 20 kHz.

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