MeasureSafe 3B Advance RCD Compliance Tester

The MeasureSafe 3B Advance RCD Compliance Tester tests RCD/ELCB/Safety Switches and ground fault detector circuit breakers that are used in mains meter boxes and as portable devices to protect personnel against faulty household and industrial circuits as a result of equipment fault or failure.

Mains mounted RCD’s along with portable units found on extension leads and integrated with power boards can fail as a result of abuse, age, corrosion, ingress of water or dirt and welded contacts.

An absolute minimum annual testing should be used. Quarterly testing is recommended as a more reliable strategy.

The MeasureSafe 36B can test all currently available RCD’s by simulating various earth leakage problems. In addition it will also report the mains voltage and incorrect wiring of outlets.

Suspect equipment can also be tested whilst in operation to provide earth leakage operating margins to identify nuisance tripping problems or faulty equipment. Simply connect the MeasureSafe 36B measure the trip current, then remove the suspect equipment redo the current trip test then the difference is the leakage current from the test equipment.

AFCI Testing

An arc fault circuit interrupter (AFCI) is a circuit breaker designed to prevent fires by detecting non-working electrical arcs and disconnect power before the arc starts a fire. The AFCI should distinguish between a working arc that may occur in the brushes of a vacuum sweeper, light switch, or other household devices and a non-working arc that can occur, for instance, in a lamp cord that has a broken conductor in the cord from overuse. Arc faults in a home are one of the leading causes for household fires.

AFCIs resemble a GFCI/RCD (Ground-Fault Circuit Interrupt/Residual-Current Device) in that they both have a test button, though it is important to distinguish between the two. GFCIs are designed to protect against electrical shock, while AFCIs are primarily designed to protect against fire.

The testing of AFCI’s is a little more difficult as we need to simulate an arc. The MeasureSafe 36B has the ability to simulate an arc that the AFCI will detect as an arc profile and then trip. Only the trip time is measured as the arc current is of little concern. Extensive work has been undertaken to generate a simulated “faulty arc” current profile.

RCD testing with isolation transformer

When conducting testing on RCD’s if the RCD is being tested on a RCD protected line there is the potential to trip the RCD at the main switch board. This is not desirable. The easiest way to do this is to use an isolation transformer and isolate the earth lead. However the transformer needs to be modified to ensure that the isolation transformer does not interfere with the normal testing.

The purpose of an isolation transformer is to electrically isolate the mains while maintaining a 1:1 voltage ratio. As simple diagram below shows an isolation transformer.

 

Normal Isolation transformer                   Modified for RCD testing

As can be seen in the simple diagram the Isolated secondary is completely disconnected from the Primary. As a result of the isolation transformer there will be no imbalance in the primary current and as such the RCD on the primary side will not trip.

In order to test RCD or to have RCD’s function correctly after the isolation transformer the Neutral Isolated must be connected to the Earth line. Other wise there is no way the RCD can function correctly and any subsequent testing will fail or give misleading results.

For continued operation protection the isolation transformer must not be left in place.

MeasureSafe 36B RCD Tester Specification