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Transformer Testing


Dielectric Voltage Testing – Standard Methods

There are two standard methods from ASTM International: D877, Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes, and D1816, Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Using VDE Electrodes. VDE stands...

Breaker Testing


Partial Discharge & Circuit Breaker Asset Management

Detecting and avoiding preventable failures BY JAY GARNETT, Doble Engineering Company While metal clad switchgear can be very reliable, sometimes operating for over 50 years, throughout the aging process, this group of electrical disconnect switches, fuses and circuit breakers can experience issues...

Dynamic Resistance Measurement

Condition testing of circuit breaker’s arcing contacts BY BUDO MILOVIC, DV-Power The preventive maintenance on a high-voltage (HV) breaker consists of several routine tests. The timing and motion tests are methods used to assess the breaker’s mechanical condition. When the timing and motion...

Power Factor Testing of Circuit Breakers

Detecting contamination and deterioration in SF6 breakers to ensure longevity BY LINDA NOWAK, Doble Engineering Company The purpose of “Doble testing”, or power factor testing, SF6 (sulfur hexafluoride) circuit breakers is to detect the presence of contamination and/or deterioration of the...

Circuit Breaker Lubrication

Developing circuit breaker lubrication procedures BY RICK YOUNGBLOOD, Doble Engineering Company Circuit breaker analyzers are used to determine operating speeds and velocity. This information enables the tester to determine if a breaker is safe to place back into service. The data recorded by a...

Circuit Breaker Time and Motion Testing

Determining mechanical condition of high-voltage circuit breakers BY JOZEF LEVI, Doble Engineering Company Life expectancy of a newly installed high-voltage circuit breaker is approximately 40 years. Throughout its life, under normal circuit conditions, the circuit breaker will operate less than...

HV Test Equipment

Vacuum Interrupter Testing for Circuit Breakers

How to predict field life using vacuum interrupters

BY FINLEY LEDBETTER, Group CBS

Utilities have widely replaced older air-magnetic and oil interrupters for circuit breakers rated at one kilovolt (kV) or higher with vacuum interrupters (VI) due to higher interrupt capability. Vacuum interrupters also last up to 10 times the expected lifetime than newer sulfur hexafluoride (SF-6) gas interrupters. Unfortunately, the downside to building a protective device with a long service life is that utility...

HV Test Equipment Articles