T&D World Magazine

Earth Testers Feature Convenience Clamp

Clamps with elliptical apertures that can accommodate cables up to 39 mm diameter and flat earth tapes up to 50 mm wide make Megger’s new DET14C and DET24C earth resistance clamp testers quick and easy to use, even with large conductors and in applications where access to conductors is restricted. In addition, these instruments are the first of their type to have a CATIV 600 V safety rating in line with EN61010, with 8 kV of transient isolation. Operator safety is further enhanced by a hazardous current warning that is operative on all test ranges.

To help ensure long-term accuracy and reliability, the instruments use clamps that have smooth mating jaw faces. These are easy to clean and they eliminate the easily bent interlocking teeth found on most other earth resistance clamp testers.

Designed to allow accurate measurement of earth resistance in multiple loop systems without the inconvenience of having to break earth connections, the new instruments can measure ground resistance over the range 50 m ohms, and true RMS ground leakage current from 0.2 mA to 35 A. As an aid to use in hard-to-reach locations, they incorporate a convenient pre-hold function that automatically initiates a test when clamped round an electrode and then holds the reading for easy review when the test is complete.

DET14C and DET24C earth resistance clamp testers are powered by standard AA batteries that are readily and inexpensively available almost everywhere. Battery life is exceptional – with a 25 ohm load, for example, up to 24 hours of continuous testing can easily be obtained from a single set of batteries.

Both models offer auto ranging, high and low alarms, automatic self-calibration and internal memory that allows results to be recorded and reviewed. Results stored in memory are automatically date and time stamped. In addition, a display backlight, along with hold key that produces an audible tone when pressed, make it easy to use the instruments even in areas where lighting is poor or access is restricted.

The DET24C adds an optically isolated USB interface that allows it to be connected to a PC, and it can calculate the maximum, minimum and average values of periodic measurements. The DET24C is compatible with Megger’s powerful data capture and analysis software packages PowerDB and PowerDB Lite, which provide a consistent platform for handling, archiving and reporting on data from power test instruments of all types.

Megger’s DET14C and DET24C earth resistance clamp testers are supplied complete with carrying case, calibration loop, batteries and a comprehensive user guide. Additionally supplied with the DET24C models are a USB interface and copy of the PowerDB Lite software package.

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