Video: VIPO-85

Video transcript

How the VIPO-85 checks the vacuum of an interrupter: the principle, the connection, the test and what the result means. A vacuum bottle that has lost its vacuum looks exactly like a good one. Nothing shows on the outside, but it can no longer clear a fault. That is why its integrity is checked at commissioning and at every maintenance, before the breaker goes back into service. With the contacts open and a high voltage across the gap, the bottle behaves like an ion tube, the same principle as a Penning or magnetron gauge.

The gas left inside is ionised, and the more gas there is, the more ions and the more current. In a good vacuum only a few microamps flow. As the pressure rises, the current climbs until it crosses the limit, and finally the gap flashes over. The VIPO-85 applies that idea directly. A regulated direct voltage, up to 85 kilovolts, is applied across the open contacts, the leakage current is measured, and it is compared with the limit you set.

The answer is a clear pass or fail, following the ANSI and I triple EDC test methods. One to 85 kilovolts in one kilovolt steps, with point 3 milliamps continuous at full voltage. Pass or fail limits of 100, 200 or 300 microamps, a resolution of one microamp, and 9.4 kilos for the complete system. Everything is on one panel. The red lamp lights whenever high voltage is present. The power and test button, the touch display, the printer and the USB port.

On the left, the high-voltage output and return leads, and below them the ground lead, which is always the first connection. The instrument works from inside its case, and the cables stay connected between jobs, so there is nothing to set up. It is ready two seconds after power-up, runs on 100 to 240 volts, or on a replaceable lithium-ion battery in the VIPO-85 B version. The order does not change. The breaker is disconnected from the network and open. The VIPO-85 is grounded first.

Then the return lead goes to one side of the bottle, and the high-voltage lead to the other, with the cable fully extended. Power comes last. Here is the connection. The green and yellow ground lead to station earth. The blue return lead to the lower terminal of the open interrupter. The high-voltage lead, the grey cable with the red clip, to the upper terminal, stretched out fully and away from anything grounded. Then the mains cable.

On the touch screen, choose the vacuum interrupter test. Set the test voltage in one kilovolt steps, to the value the breaker maker or the applicable standard gives. Choose the pass or fail limit, and a test time from two seconds to two minutes. Press and hold the test button. The voltage rises to the set value, the red lamp and the tone warn that it is live, and the leakage current is measured for the set time. The verdict appears, and the voltage is removed and discharged in under 3 seconds.

Reading the result is simple. Leakage below the limit is a pass: the vacuum holds. Leakage above the limit is a fail. A flashover stops the test, because the gap cannot hold the voltage. Either way, the bottle does not go back into service. The same instrument is also a compact DC hipot. In HiPot mode it shows kilovolts, microamps and teraohms, holds 85 kilovolts at 300 microamps continuously, and stops at a limit set from 25 to 300 microamps. Every test is stored with its date and time, up to 200,

and can be printed on site on the built-in thermal printer. Results are transferred with a USB flash drive, the same way the firmware is updated. The key figures: output accuracy of 1.5% with ripple below two percent, current accuracy of two percent of full scale, operation from zero to 50 degrees, and 5 to 95% humidity without condensation. It is used wherever vacuum breakers are commissioned or maintained: medium-voltage switchgear in the field, periodic maintenance,

and acceptance tests in the workshop, with the printed record as evidence. Circuit breaker testing, from Amperis.