Megger VIDAR Vacuum Interrupter Tester
Megger harnesses their knowledge and experience within the power circuit industry, plus over one hundred years‘ of high quality instrumentation production to manufacture VIDAR. This model of vacuum interrupter presents a superior alternative to AC Hi-Pot testing.
Insulation integrity testing is recommended by the manufacturers of circuit breakers, and well documented in international test standards such as IEC and IEEE.
VIDAR has a user-friendly pass/fail test procedure where a light indicates the test result. The procedure avoids unneeded misinterpretations based on normal fluctuations of stray currents. Those are mostly due to test environment variables such as relative humidity, or polluted surfaces of the test object.
The Megger VIDAR vacuum interrupter tester is used to test the ability of the vacuum chamber to inhibit flashovers. VIDAR is rugged, lightweight, compact and portable so ideal for field work and shop floor applications.
The internal pressure of vacuum chambers do not last forever. Leakage starts after years or decades and the bottles fill with air making the circuit breaker unreliable. In most cases the leakage process is rapid once it has started. In addition to leakage, dirt on the poles and on the exterior surface of the bottle can make it unsafe during operation.
The mechanics of the breaker can become misaligned so that the distance between the poles no longer is adequate. When a vacuum circuit breaker is commissioned or undergoes routine tests, it is very important to be able to ascertain whether or not the Vacuum Interrupter (VI) is intact before putting it back into operation.
VIDAR enables you to check the integrity of the vacuum interrupter quickly and conveniently by means of the known relationship between the flashover voltage and the vacuum interrupter. A suitable test voltage (DC) is applied to the breaker, and the result is known immediately.
Megger VIDAR Key Features:
- Traditional AC equipment is more than ten times the weight of VIDAR
- Tests the integrity of vacuum interrupters quickly, safely and easily
- User defined voltage selection
- Extensive voltage range
- Easy to operate. Follows ANSI/IEEE standardised DC test methods
- Lightweight and portable
How to use Megger VIDAR:
A typical test of a vacuum circuit breaker follows a simple sequence:
- Make sure the circuit breaker is secured and safe to work upon
- Put it in the open position
- Ground both test instruments and test object to the same point
- Apply HV test leads across the first phase vacuum bottle
- Set the test voltage selection switch to the voltage nearest to the desired test voltage given in the circuit breakers manufacturer‘s specification
- Twist the double command, and note the test result
- You can now repeat the sequence for phase two and three
ALWAYS check the manual before using any test instrument
History of vacuum insulation media in switchgears
Since the 1950’s vacuum has been used as insulation media in switchgears. Even though that technology has proven to be very reliable, over time air will leak into the vacuum chamber and degrade the insulation. Also, a good practice is to measure after transport or accidents. The accepted way to test the vacuum integrity has always been via a voltage withstand test. For field tests, DC test is preferred due to the weight and size of the instruments.