Vacuum interrupter tester

Data records

• A direct-voltage tester is far lighter than an alternating-voltage one because the resistive current that reveals a loss of vacuum is many times smaller than the capacitive current the interrupter draws under alternating voltage, which makes the resistive component hard to distinguish in an alternating-voltage test. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.direct-versus-alternating
• The direct-voltage test relies on the known relationship between the flashover voltage of the interrupter and the integrity of its vacuum; the test voltage is taken from the breaker manufacturer's recommendation or derived from the manufacturer's recommended alternating test voltage, and the result is indicated at once as pass or fail. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.flashover-relationship
• Flexible magnetic field coils wrapped several turns around the interrupter, or rigid coils placed around the external insulating housing where the interrupter cannot be reached, let the MAC test be made with the interrupter still mounted in its breaker or contactor, in the field or in the shop. Source: Group CBS article page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.mac-in-place
• The magnetron atmospheric condition (MAC) method runs the Penning discharge test that interrupter manufacturers use at the factory: with the contacts open a high direct voltage is applied for a short time while a magnetic field from a coil wrapped around the interrupter traps the charge carriers, and the current measured depends on the number of gas molecules present, so a lower current means a better vacuum. Source: Group CBS article page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.mac-method
• Because the MAC reading quantifies the condition of the vacuum rather than giving a pass or fail, readings tracked over time can be extrapolated to estimate when the vacuum will no longer interrupt current; the first MAC test on an interrupter gives the most valid reading because the test itself temporarily affects the internal pressure. Source: Group CBS article page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.mac-pressure-and-life
• A vacuum interrupter tester checks whether the vacuum inside the sealed interrupter of a medium-voltage circuit breaker is still intact, and therefore whether the breaker can still interrupt a fault current; the interrupter is tested in place without dismounting it from the breaker. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.purpose
• Contamination on the outside of the interrupter conducts a small current under the applied direct voltage and can fail a sound interrupter, so the surface is cleaned and dried and the test repeated, with the lead clamps moved to the opposite positions, before the interrupter is judged defective. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.surface-contamination
• The instrument class is written Vacuum interrupter tester. Value: Vacuum interrupter tester. Source: Electrical Testing Reference editorial taxonomy, 2026-10 edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.title
• The go/no-go method applies a direct test voltage across the open contacts and holds it for a set time; if the leakage current stays below a preset limit for the whole time the result is a pass, while a flashover or a current above the limit returns a failure and the voltage is shut off at once. Source: Doble product page, web page edition. Verified 2026-10-27. Record instr.vacuum-interrupter-tester.withstand-method