Identifying deterioration of installation and other causes of “nuisance tripping" of an RCD (Residual

Current Device) in live circuits is not always a straightforward matter. Problem of access and

isolation may make the inspection costly and takes time.

Then, let's look at KEW Leakage Clamp Meters designed to take the stress out of inspecting live

installations.

IF AN RCD TRIPS

Imagine an electrical contractor is called in to deal with a fault which has shut down a complete

installation, or part of it. He finds that the supply has been lost, because a 30mA RCD protecting the

faulty circuits has tripped. He closes the RCD only to find that tripping occurs again or just a few

hours later.

What steps should he takes to trace the fault?

Since an RCD senses an imbalance between the phase and neutral currents in a circuit, the

contractor is faced with identifying the source of the leakage current to earth which is causing the

device to trip.

One possible path this leakage current may take is through the phase/earth insulation resistance

and, therefore, he decides to perform an insulation test by an insulation resistance tester.

But to perform the insulation test in order to trace the fault means to disconnect and separate the

different lines, the appliances from the installation. His customer, however, is anxious to minimize

installation downtime.

In addition, the faulty circuit may serve sensitive electronic systems which are likely to be damaged

by the high voltage generated by insulation test.

How can the contractor resolve this problem?

KEW LEAKAGE CLAMP METERS REALLY HELP

Now, thanks to AC Leakage Clamp Meters developed by KYORITSU, he can make not only a

precise measurement of the earth leakage current in a circuit, but also an instant assessment of the

cause of that leakage without shutting down the installation.

Several models are available for him to choose; the most compact model 2431, the large jaw

models 2413F / 2413R, the very high resolution model 2432, versatile models 2433 / 2433R and

the cost effective model 2434. The substantial time and money saved in using these instruments

will repay their costs after only a few visits on site.