Video: AMRU-200 GPS

Video transcript

The AMRU-200 GPS measures every kind of earth and stores where each result was taken, how the position is recorded, and how it is connected for four wires, towers, impulse and soil resistivity. A substation has dozens of electrodes, and a line has a tower every few hundred meters. After a day of tests, the hard part is knowing which result belongs to which earth. With the position stored next to each result, the report writes itself. A built-in GPS receiver with three-meter accuracy,

three- and four-pole earth resistance up to nearly 20 kOhm. The impulse method with three lightning waveforms, and a clamp, two clamp, and soil resistivity methods. The screen shows each result with date, time, and coordinates. The terminals run along the top edge, clamp socket, E, ES, S, and H. The rotary switch selects the method, start runs it, and F4 shows the position. GPS is switched on in the menu. While it searches for satellites, the icon blinks.

Once it has a fix, it stays on. From then, on every result carries its coordinates, and F4 shows them on the screen. In the open, the position is accurate to about three meters. On sight, the routine is always the same. Turn the switch to the method, set the test voltage or the pulse shape with F1, connect, press start, and store the result, which keeps its position. For low earth resistances, use four wires. Disconnect the electrode, then connect E to it,

S to the voltage probe, and H to the current probe, all in line. Finally, add ES on the electrode below the E-lead. The resistance of the E-lead drops out of the result. Check every result. Move the voltage probe a few meters both ways. If readings differ by more than 3%, move the current probe further out. The meter shows the probe resistances and the uncertainty they add, and flags limit above 30%. a lattice tower, the line can stay in service.

E goes to the leg under test, S and H to their probes in line. A flexible clamp goes round the same leg below the E-clip through the flexible clamp adapter to the clamp socket. Each leg is measured in turn, and the meter combines them. meter is told how many legs the tower has, and measures them one after another, showing each leg's resistance before the resulting earth resistance. No line outage. No test joints to open. And with GPS, every tower is recorded where it stands.

lightning current rises in microseconds, so the inductance of the earth conductors matters. The impulse method sends pulses shaped like lightning, with three standard waveforms, and divides the peak voltage by the peak current. It is meant for lightning protection earths. the switch to four-pole impulse. E goes to the down conductor, and the H lead shield joins E. E-S goes below E on the same conductor.

S and H go to their probes, leads fully unrolled, and at least 60 degrees apart, with the test joint closed. For soil resistivity, drive four probes in a straight line at equal spacing L. From first to last, they go to E, E-S, S, and H. The meter asks for L in meters or feet, and calculates two pi times L times R. Each result is stored with its position. 990 results in 10 banks of 99 cells, each with date, time, and position. They go to the computer over USB or Bluetooth,

or straight to a phone app on site, and from there into the inspection report. Measuring Category 4 at 300 volts, an IP54 case, about 2 kilos, and a rechargeable pack that can also be charged from a car socket between sites. Earthing networks of substations and industrial plants, transmission towers and service, lightning protection by impulse, and soil surveys for new designs, each result tied to its place. Earth resistance testing from Amperis.