The AMRU-200 measures earth resistance by the 2-, 3- and 4-wire methods, with a clamp for multiple earth electrodes and with two clamps when auxiliary electrodes cannot be driven into the ground, as well as earth impedance by the impulse method, soil resistivity and leakage current with a clamp.
Measurement methods
- Earth resistance using auxiliary electrodes, by the 2-, 3- and 4-wire method.
- Earth resistance using auxiliary electrodes and a clamp, for multiple earth electrodes.
- Earth resistance using two clamps, when auxiliary electrodes cannot be driven into the ground.
- Dynamic earth resistance (impedance) by the impulse-wave method, with a 4/10 μs or 10/350 μs test impulse.
- Soil resistivity by the Wenner method, and leakage current with a current clamp or a flexible clamp.
- Continuity of equipotential bonding and protective conductors, with auto-zero and a 200 mA test current, to IEC 60364-6-61:2000 section 6.12.2.
Applications
The impulse method checks the earthing of lightning protection systems, simulating the current wave of a strike without needing to disconnect the circuit, which is especially useful on lattice towers and lines where service should not be interrupted. The clamp and double-clamp methods verify multiple and interconnected earths, and the automatic or manual selection of the mains frequency (16 2/3 Hz, 50 Hz, 60 Hz or 400 Hz) allows work next to railway or industrial lines with particular interference.
Power, memory and software
It runs from a rechargeable 4.8 V 4.2 Ah Ni-MH battery pack, giving over 300 measurements per charge and recharged through the supplied Z7 adaptor or a car cigarette-lighter cable. It stores up to 990 measurements in 10 banks of 99 cells, each with the real-time clock's time stamp, and transfers them to a computer over the supplied USB cable. An optional PC application for creating measurement documentation completes the meter, installed on a computer to organise and print the downloaded readings.
Technical specifications
| Earth resistance (3- and 4-wire) | 0.00 Ω...19.9 kΩ; to IEC 61557-5, from 0.10 Ω |
| Resistance with clamp (3-wire + clamp) | 0.00...1999 Ω; to IEC 61557-5, from 0.12 Ω |
| Resistance with double clamp | 0.00...149.9 Ω |
| Earth impedance (impulse method) | 0.0...200 Ω, 4/10 μs or 10/350 μs impulse |
| Soil resistivity | 0.00 Ωm...999 kΩm (Wenner method) |
| Leakage current with clamp | 0.1 mA...300 A |
| Protective continuity | 0.00 Ω...19.9 kΩ; to IEC 61557-5, from 0.045 Ω |
| Measurement category | CAT III 600 V, to EN 61010-1 |
| Protection rating | IP54 |
| Memory | 990 measurements (10 banks of 99 cells) |
| Warranty | 36 months |
Frequently asked questions
What is the impulse method used for?
To measure the dynamic resistance (impedance) of lightning protection earths, with a 4/10 μs or 10/350 μs test impulse.
Can it measure leakage current?
Yes, with a current clamp or a flexible clamp, over a range from 0.1 mA to 300 A.
Which mains frequencies does it filter against interference?
It filters interference at 16 2/3 Hz, 50 Hz, 60 Hz and 400 Hz, with automatic or manual selection.
How are measurements transferred to a computer?
Through the supplied USB cable.
How many measurements does it store?
Up to 990 measurements, organised in 10 banks of 99 cells, each with the date and time from the real-time clock.
