Megger’s popular 4-terminal ground testing instrument family includes four basic models with different kit variants for each that include select accessories for greater testing flexibility.
The top-end models (DET4TC2 and DET4TCR2) include a current measuring function for ART (Attached Rod Technique) testing capabilities. With this added function, on-site grounds can be tested separately without having to remove the utility connection (as explained further in this document). They also provide stakeless testing capability. This method allows the operator to use the instrument like a clamp-on ground tester in applications where that method is viable, while also being able to operate as a fall of potential tester if required.
The basic kit includes the test leads, stakes, batteries and calibration certificate, delivered in a tough polypropylene carry case – everything you need to start testing in one package.
All models are rated to IP54, making them truly outdoor instruments. They are designed to meet stringent safety standards and are rated CAT IV 100 V. The ground testers have been designed to be easy to use – a large selector switch makes selection of 2, 3 or 4 pole tests easy with gloved hands – and the design makes the fitting of shorting links to perform 2-pole tests a thing of the past. A large, clear, easy to read LCD and thumb sized test button also make the instruments particularly well suited to the outdoor conditions of ground testing. In addition to this ease of use feature, the instruments automatically check the connection and conditions of the P spike, C spike, and also the level of ground noise, indicating the status on the display. They also include a voltmeter to enable measurement of ground voltage.
The DET4TD2 and DET4TR2 can measure resistance from 0.01 ohms to 20 kΩ, while the DET4TC2 and DET4TCR2 can measure resistance from 0.01 ohms to 200 kΩ, a key capability for soil resistivity testing. Also, to allow accurate testing in noisy environments, the instruments are capable of rejecting noise up to 40 V peak to peak.
The DET4TD2 and DET4TC2 are powered by eight AA batteries which are widely available and also give excellent testing time – the status of these batteries is given by a bar graph on the LCD display, allowing the operator to decide when to change the batteries before they expire. The DET4TR2 and DET4TCR2 are powered from rechargeableAA cells. The battery charger is built in and the instrument is supplied with an AC/DC adapter. For all instruments, the battery status is displayed using a bar-graph.
The DET4TC2 and DET4TCR2 include additional capabilities. By using the optional ICLAMP the user can augment the traditional fall-of-potential measurement method with ART (Attached Rod Technique), which allows electrode testing without disconnection and also leakage current measurements down to 0.5 mA. A second optional clamp, the VCLAMP, enables true stakeless (clamp-on) measurements to be made in situations where driving stakes is not practical.
The DET4TC2 and DET4TCR2 also feature a backlit display, which extends the operational environment of the instrument to cable cellars and other dark locations. Finally, all units have selectable 25 V or 50 V output for compliance with IEC 61557-5. The 25 V output is required for testing in agricultural environments.