Video: AMIC-5010

Video transcript

What the AMIC-5010 measures, how it is connected for two-lead, three-lead and continuity tests, and how to read PI, DAR and DD. Insulation ages with heat, moisture and dirt, long before it breaks down. Measuring its resistance at a high DC voltage, and how that resistance changes with time, shows the ageing early. Any test voltage from 50 volts to 5 kilovolts, resistance up to 15 teraohms, a test current of 1.2 or 3 milliamps, and the indices PI, DAR and DD. Three test sockets on the right:

plus, the guard G, and minus, with a shielded socket. The rotary switch sets the test voltage or the function. MENU and the F keys set the parameters, and START runs the test. The case carries 3 test leads rated 11 kilovolts, in red, blue and black, with probes and crocodile clips. There is also the mains cable, the USB cable and the calibration certificate. Leads up to 20 metres are options. Apply a DC voltage and the current falls with time.

The capacitance charges in seconds; the absorption current fades over minutes; what remains is leakage. So sound insulation shows a rising resistance, and damp or dirty insulation a flat one. Every test follows the same routine. Make the object dead, and keep it earthed until the leads are on. Choose the voltage. Set times, current and limit with MENU. Connect. Hold START, or lock it with ENTER.

Then wait for the automatic discharge. Two leads, on a power cable. The other cores and the screen are bonded together and earthed. The red lead, R ISO plus, goes to that bonded group, and the black lead, R ISO minus, to the core under test. Repeat for each core. With R ISO plus on the screen and R ISO minus on the core, stray currents and electric fields in a substation disturb the reading far less. A long cable can rebuild its charge after the test,

so earth its cores again before you remove the leads. Three leads, on a transformer. The blue guard lead goes to the tank. The red lead goes to the bonded high-voltage terminals, and the black lead to the bonded low-voltage terminals. The result is the insulation between the two windings. Current creeping over a damp or dirty surface would add to the leakage through the insulation.

The G socket collects it and leads it past the measurement, so only the volume resistance is measured. DAR divides the one-minute reading by the 32nd reading. PI divides the ten-minute reading by the one-minute reading. Being ratios, they depend far less on the size of the object than the resistance itself. The step voltage test applies 5 rising voltages, up to 5 kilovolts: sound insulation gives the same resistance at every step.

Dielectric discharge measures the current one minute into the discharge; a DD below two is good, above 7 is bad. Next to live high-voltage plant, the meter tells mains voltage from induced voltage. Mains voltage blocks the test for safety; induced voltage does not. Digital filters of 10, 30 or 60 seconds, on the F one key, steady the reading. For protective conductors, switch to R CONT: 200 milliamps or more, in both directions. First zero the leads: short them, press F two and START.

Then red to the main earthing terminal, and black to the exposed part. Results go to 990 memory cells, and transfer over USB or Bluetooth. An Android app plots resistance and leakage current live, so the operator can stay clear of the object. Measuring category 4 at 600 volts. A case rated IP 67 when closed. Minus 20 to 50 degrees. And a lithium iron phosphate battery good for at least 1000 tests, or mains power. Power and distribution transformers, motors and generators,

medium-voltage cables and switchgear, in power plants, industry and substations, including work next to live busbars and lines. Insulation resistance testing, from Amperis.