Video: AMZC-310S

Video transcript

How the AMZC-310S measures very low fault loops with a current of up to 280 A, why it uses four leads for that, and how it also measures touch voltage. Close to a transformer or a mainboard, fault loops are a few milli-ohms. At that level, the resistance of the test leads and a test current of a few A are no longer good enough. You need a high current and a separate pair of leads that measures only the voltage. methods in one meter, four poles with up to 280 A, and a resolution of a tenth of a milli-ohm.

Two poles with up to 42 A, from 0.13 ohms, and touch voltage up to 100 volts. The six sockets are on the right, I1 for 280 A, U1, U2, I2, the touch voltage socket, and I1 for 42 A. The rotary switch selects voltage, two poles, for poles, or memory. START runs the test. The kit holds black and yellow 1.2-meter leads with probes for the two-pole method and two 3-meter twin cables, U1I1 and U2I2, with Kelvin clamps and high current probes for the four-pole method.

Also crocodile clips, a case, a harness, an RS-232 cable, and 5 C cells. Set the rated network voltage in the menu. 220 or 230 volts phase to neutral. Choose two poles or four poles with the switch. For two poles, set the lead length. Connect, check the voltage and frequency on the display, and press start. two-pole method uses two leads, like any loop tester. For the LPE loop, the yellow lead goes from I2 to the protective conductor,

and the black lead from the 42 amp I1 socket to the phase. The resistance of the leads is taken into account from their length. The four-pole method separates current and voltage. I2 and U2 go to the same point of the protective conductor, I1 and U1 to the same point of the phase, each pair in a Kelvin clamp. The current flows through the I leads, and the U leads read only the drop across the loop, so the leads need no calibration. four poles? Two leads measure their own resistance along with the loop.

With separate voltage leads, almost no current flows in them, so they add nothing. And a current of up to 280 amps gives a clear drop even across a few milli-ohms. With four poles, the meter also measures touch voltage. I1 and U1 go to the phase, I2 and U2 to the housing of the equipment, and the UST socket to a separate earthing bar. For the shock voltage, a probe on the floor replaces the bar, and the meter adds a one-kilohm resistor that represents the body. As with any loop tester, the meter measures impedance and calculates the prospective

short circuit current from the rated voltage, phase to neutral, or phase to phase. With four poles, the range goes up to 32 kiloamps at 230 volts and 55.7 at 400. Our RCDs and the circuit have to be bridged during the test, then restored and checked. Measurements just downstream of inverters are not reliable. Above 440 volts, the meter warns and must be disconnected at once, and it must never be left connected unattended. Using a phase of the installation as the source, the meter can also give a quick check of an earthing resistance.

The result includes the source and the phase conductor, so it airs on the safe side. If it is below the limit, the earthing is good enough. Results are stored in 990 memory cells, 10 banks of 99, with the network voltage and frequency, and sent to the PC over RS-232, or over USB with the adapter. Measuring Category 4 at 300 volts, 5 C cells for at least 2,000 measurements, a built-in fan, and 2.2 kilos in a case with the connection diagrams printed inside the lid.

Main and sub-distribution boards close to the transformer, industrial installations with very low loop impedance, bus bar systems, and touch voltage checks on equipment housings. loop testing, from Amperis.