Video: AHZAQ – Technical guide

Video transcript

How the AHZAQ is set up and connected, how a test area at 100 kV is made safe, and how gloves, boots, sticks, blankets and detectors are tested, step by step. This is a high voltage test at up to 100 kV. Only trained staff work on it. The test area is fenced, with the warning light in sight, and nobody is inside the fence while voltage is applied. Everything is earthed before anything else is connected, and after every test the high voltage parts

are earthed again before they are touched. The system is made of the control unit, the test transformer of 50 or 100 kV, the protection resistor, the high voltage divider, and the test bath. The fixtures for sticks, blankets and detectors are added when needed, and everything can travel on a trailer. connection, earth first, the control unit, the transformer, the divider, and the bath all go to the earth bar. Then the low voltage output of the control unit to the transformer primary.

From the transformer, the high voltage goes through the protection resistor to the bath. The divider taps the high voltage, and its output returns to the measurement input. Every test follows the same order. Earth the whole system. Connect the low voltage and the high voltage circuits. Load the items. Leave the fenced area and close it. Set the test and start it from the console. And after the test, earth the high voltage parts before entering.

For gloves and boots, the bath does the work. Gloves are tested with water inside and outside, as the standard describes, with the electrode inside each glove. Boots stand in the tubs and are filled with 4 mm steel balls, which act as the inner electrode. Each item hangs from its own high voltage position. On the console, set the test for the item and its class. The test voltage and the time required by the standard,

the rate at which the voltage rises, and the leakage current limit. Then the item type, so that it appears on the report. Start the test from the console outside the fence. The voltage rises at the set rate. The timer starts at the test voltage, and the display shows the 8 leakage currents live. At the end, the voltage returns to 0, and the unit switches off. If an item breaks down, its position is disconnected at once,

and the other 7 carry on. Reading the result is simple. An item fails if it breaks down, or if its leakage current is above the limit for its class. In the report, a position that reads far above the others deserves a closer look even if it passed. In this boot test, 7 red about 0.02 mA and 1 red 0.46. Hot sticks go on the remote control bracket.

It has 8 stations and 3 sets of electrodes. The center one at high voltage, the outer one's earthed, opened and closed by motor from a remote control. 35 kilovolt sticks are tested whole. Sticks up to 110 kilovolts are tested in segments, at 100 kilovolts every 300 millimetres. Blankets, mats, covers, and insulating clothing are tested on the insulated bench. Its center has an embedded earth electrode,

and stainless steel electrodes go on top of the item. Matching electrodes are supplied for sleeves, chest, and trousers. Capacitive voltage detectors of 10 to 35 kilovolts are checked on their own stand. The high voltage electrode is a sphere, the earth electrode a fixed ring. The sphere moves by motor, from buttons, or a wireless remote, with fine adjustment and a scale, so the detector is tested at the right distance without anyone near it. When the test ends, wait until the voltage is

at zero and the warning light has changed. Then, before opening the fence, earth the high voltage parts with the earthing rod. Only then are the items removed, dried and marked, and the next batch loaded. The whole system can be mounted on a trailer and taken to the cruise. On site, the same rules apply. A firm, dry place, a good earth, the fenced area, and the warning light, before the first item is tested. Dielectric testing, from Amperis.