Due to the increasing use of type B RCDs to protect systems with power electronics equipment (e.g. frequency converters), these RCDs are also being triggered more frequently without the conventional testing methods being able to detect a fault in the system. The cause of such false triggering is usually differential currents in the form of capacitive leakage currents with frequencies that deviate from the mains frequency and that flow to earth via real or parasitic capacitances (e.g. EMC capacitors or line capacitances). Depending on the type of electronic equipment, leakage currents can have very different frequency mixtures. Since these differential currents also cause a contact voltage at the earthing resistance of the electrical system, they must be detected by an RCD and trigger a trip. Measuring systems in this class enable the analysis of differential currents and differential current mixtures whose frequency deviates from the mains frequency. In most cases, the analysis results allow conclusions to be drawn about the causes of the leakage current and thus provide information about measures to reduce it so that a type B RCD can be used without any problems. Measuring devices in the DRCA series offer complex analysis tools for determining the origin of residual currents and selecting suitable RCDs. The set consists of the following components: 1. DRCA 1 measuring unit: The DRCA 1 measuring unit analyses the measured values and prepares them for further processing on the PC, which is connected to the measuring unit via a standard USB port. 2. DRCA 1-MC measuring line: The DRCA 1-MC measuring line ensures that the measured values are transmitted to the measuring unit without distortion. 3. DRCA 1-CT70 measuring through-current transformer: The residual current transformer includes all active conductors leading to the consumers and its output signal shows the temporal progression of the sum of all conductor currents flowing through it. Its output signal is proportional to the differential current (fault current) that flows back to the earthing point of the supply network via the protective conductor or the earth in the event of an insulation fault. The level of the differential current is evaluated from this signal by the measuring unit of the analysis system and forwarded to the connected PC for display. 4. Analysis software DRCA 1-SW: The analysis software DRCA 1-SW provides a variety of functions for displaying and evaluating the measured values. Properties: Through-hole converter DRCA 1-CT70: - 70 mm inner diameter, - suitable for recording differential currents from 10 Hz to 100 kHz, - other inner diameters available to adapt to the cable to be monitored, - robust plastic housing, - reverse polarity protected connection socket for measuring line, measuring line DRCA 1-MC: - cable length 3 m, - reverse polarity protection thanks to plug/socket arrangement, measuring unit DRCA 1:- suitable for recording residual currents from 10 Hz to 100 kHz and an amplitude of up to 10 A, - immunity to DC residual currents of up to 3 A with a maximum of -10% measurement deviation, - robust, handy plastic table housing, - reverse polarity protected connection sockets for measuring cable and USB cable, - LED to display the operating status, Analysis software DRCA 1-SW: - diverse analysis functions, including display of the signal curve of the residual currents, analysis of the frequency spectrum (Fourier analysis), display of the effective values, long-term measurement with storage of the measured values for later detailed evaluation, recording of the signals by defining trigger conditions to determine switching operations or sporadically occurring residual currents, - intuitive operation, - runs under Windows 7, Windows 8 and Windows 10, Mounting type: Measuring unit DRCA 1: - table device for setting up on flat surfaces, Measuring through-hole transformer DRCA 1-CT: The device is attached to load-bearing surfaces