Low-resistance testing

Louise Smyth

With the new and exceptionally versatile four-terminal test lead system from Megger, users of low-resistance test sets no longer have to carry around multiple lead sets to suit specific applications. Instead, Megger’s new system features test leads equipped with duplex connectors, allowing the correct type of termination for almost any test to be fitted almost instantly.

This arrangement is not only convenient, since the weight and bulk of multiple lead sets is eliminated, it is also economical, as users pay for only one lead set instead of many.

An additional key benefit is that the new leads are optionally available with integral LED indicators that work with the DLRO10 series of instruments. These give a warning if connection is made to a hazardous live voltage, as well as showing when continuity is achieved, when the test is complete and, if used with Megger DLRO10X test sets, whether the test results are within user-adjustable pass/fail limits. The LED display is at the end of the test lead remote from the instrument, and it therefore allows users to monitor progress from the test location, even if the instrument is out of sight.

The new test leads can be supplied in 1.5m, 3m and 6m versions with and without LED indicators for use with the popular Megger DLRO10, DLRO10X and DLRO10HD test sets. Leads in the same lengths are also available for use with older BT51 test sets, but these instruments do not support LED functionality. As a further aid to versatility and convenience, 6 m extension leads are offered for use in conjunction non-LED test leads.

At the heart of Megger’s new low-resistance test lead system is a bespoke connector that allows terminations such as Kelvin clips and duplex test probes to be fitted and changed as required. The connectors hold the selected terminations securely in place with a push-and-twist retaining mechanism that is fast and easy to operate.

As well as the leads themselves, the system includes five types of termination. The duplex connect probe terminations are ideal for general-purpose use and incorporate replaceable probe tips with hardened gold-plated needle points. Duplex connect twist probe terminations are designed so that, as the probe is pressed against the test piece, the tips compress and twist, allowing them to cut through surface coatings or corrosion. Concentric duplex connect probe terminations feature a long small-diameter probe tip, which means that they can easily reach even deeply recessed terminal screws.

The range of terminations for Megger’s low-resistance test lead system is completed by two types of Kelvin clamp. The first is a heavy-duty clip for standard applications which has a capacity of 40mm, while the second is a fully insulated touch-proof clip for applications where a high safety rating is required. The fully insulated version has a sliding jaw that can be adjusted from 52mm to 75mm maximum capacity.