Megger DET4T2 Series Four-Terminal Earth Ground Resistance Tester

Overview

The Megger DET4T2 series is a family of four-terminal earth and ground resistance testers that also measure soil resistivity. Four models make up the range: the DET4TD2 with dry-cell batteries and the DET4TR2 with rechargeable cells are basic testers for 2, 3 and 4 pole measurement, while the DET4TC2 and DET4TCR2 add selectable test frequencies, higher sensitivity, the Attached Rod Technique and stakeless measurement. The Megger DET4T2 range is designed for testing earth electrodes, grounding grids, lightning protection systems and bonding in outdoor environments.

An earthing system in a power station, substation, refinery, gas plant or telecom site must be proven to be low in resistance and stable over the years, and soil resistivity data are the starting point for designing it. Seven Star LLC supplies the Megger DET4T2 series from Muscat with engineering support, and our team can help you choose between the basic and clamp-capable models, the lead kits and the optional clamps for ART and stakeless testing in Oman and across the GCC.

Test Principle

The classical fall-of-potential method drives a test current through the earth electrode under test and a remote current stake, while a voltage is measured between the electrode and a potential stake placed in between. The Megger DET4T2 series supports two-pole, three-pole and four-pole connections without any shorting links, and automatic checks of the current stake, the potential stake and the ground noise tell the operator when a stake needs to be repositioned. The four-pole connection of the Megger DET4T2 is also used for soil resistivity testing.

The DET4TC2 and DET4TCR2 add the Attached Rod Technique, which allows electrode testing without disconnection when used with the optional MCC clamp, and stakeless measurements with the optional MVC clamp for situations where driving stakes is impractical. Leakage current can be read down to 1 mA with the clamps. To avoid interference from stray currents, the operator can select one of four test frequencies of 94 Hz, 105 Hz, 111 Hz and 128 Hz and one of two output voltages, 25 V or 50 V, for compliance with IEC 61557-5.

Engineering Design of the Megger DET4T2 Series

The Megger DET4T2 instruments are built with a large rotary selector switch and a one-press test button that can be used with gloved hands, and a high-contrast liquid crystal display with a backlight so the readings can be seen in sunlight and in dark cable cellars. The DET4TC2 is powered from eight AA cells, and the DET4TCR2 uses rechargeable NiMH cells with a built-in charger and an AC and DC adaptor, with the battery state shown as a bar graph. The housing is rated IP54 and the operating temperature range is -15 to +55 degrees Celsius.

On the Megger DET4T2, safety is covered by compliance with IEC 61010-1 for 100 V CAT IV between terminal pairs, which depends on the use of a leadset of at least that rating, and by compliance with EN 61557 parts 1 and 5 and KEMA K85B. The standard kit includes a hard carry case, stakes and a wire set of 15 m, 10 m, 10 m and 3 m, terminal adaptors for bare wire and a calibration certificate. Kitted options add the MCC and MVC clamps and a calibration check box, and professional kits include a 2 x 50 m and 2 x 30 m set of leads with spikes in a weatherproof holdall.

Key Features

The following characteristics show why the Megger DET4T2 series is used for earth system verification:

• Two, three and four pole measurements with no shorting links, and automatic C stake, P stake and noise checks.
• Resistance measurement from 0.01 Ω to 20 kΩ in 2, 3 and 4 pole modes and up to 200 kΩ with the Attached Rod Technique.
• Stakeless measurement from 0.01 Ω to 200 Ω with the MCC and MVC clamps, and ground current measurement from 0.5 mA to 19.9 A.
• Ground noise voltage measurement from 0 to 100 V AC and rejection of noise up to 40 V peak to peak.
• User selectable test frequency of 94, 105, 111 or 128 Hz and selectable output of 25 V or 50 V.
• IP54 enclosure, backlit display and a robust carry case for outdoor use.
• CAT IV 100 V safety rating and compliance with EN 61557 parts 1 and 5.
• Delivered with a calibration certificate and available with dry-cell or rechargeable power.

Industrial Applications

Earth resistance testing is required at commissioning and at regular intervals on substations, transmission towers, power plants, oil and gas facilities, wind and solar farms and communication sites. In Oman, where soil is often dry sand or rock and seasonal variation affects results, a tester such as the Megger DET4T2 with selectable frequency and strong noise rejection is valuable for energised sites. Utilities and contractors in Muscat, Sohar and Salalah use the Megger DET4T2 series to verify electrodes, bonding of tanks and pipelines, and grounding grids at fuel terminals and process plants.

Because a good earth is also essential for instrumentation, communications and lightning protection, maintenance teams often equip a toolkit that combines the Megger DET4T2 with a Fluke 87V industrial multimeter, a Infratek 23DC-Source battery tester for standby power systems and a Fluke 5502A multi-product calibrator for laboratory checks. Seven Star LLC can quote the complete set with the correct leads, clamps and carry cases.

Technical Specifications

The data below are drawn from the Megger datasheet for the DET4TC2 and DET4TCR2; the basic DET4TD2 and DET4TR2 omit the ART, stakeless and frequency selection functions.

Request a Quote for Megger DET4T2

Contact Seven Star LLC for a quotation on the Megger DET4T2 series, and tell us which kit you prefer: basic, with MCC and MVC clamps, or with the ETK50C lead set. We will confirm stock in Muscat, share the official datasheet and arrange delivery to your site in Oman or the GCC. Our instrumentation team can also advise on the number of test spikes and cable reels so your Megger DET4T2 kit is complete from day one.