Switchgear Breaker Testing in Carolina: Testing for MV Circuit Breakers

The interrupting mechanism and voltage class determine the types of tests that switchgear requires. The focus is on breaker testing for medium voltage (MV) gear that interrupts arc faults using oil, air, vacuum, or SF6 (sulfur hexafluoride) breakers. In the Carolina area, Prime Power performs switchgear breaker testing for commercial and industrial power users. Essential for protecting assets and workers, switchgear testing should be performed on a routine basis. To determine the testing schedule for your facility's breaker system, contact Prime Power.

Tests for MV Oil, Air, Vacuum and SF6 Breakers

Commercial and industrial buildings contain MV circuit breakers that feature various types of interrupting mechanisms, with oil, air, vacuum, and SF6 mechanisms being the most common. There are several tests that apply to all MV breakers, but certain tests are based on the interrupting mechanism. Below are tests that are performed on MV oil, air, vacuum, and SF6 circuit breakers based on the interrupting mechanism:

Oil Interruption

Oil circuit breakers extinguish arcs by blasting them with a jet of vaporized oil. Tests for this interrupting mechanism are:

• Oil dissolved gas analysis test
• Oil dielectric test
• Oil acidity test
• Oil interfacial tension test
• Oil power factor test
• Water in oil test
• Oil density test

Because oil can degrade, creating problems with the interrupting mechanism, oil circuit breakers require the most tests based on the interrupting mechanism.

Air Interruption

Air circuit breakers extinguish arcs by blasting them with a jet of compressed air, or by swinging the contacts into a sealed chamber. Tests for this interrupting mechanism are:

• Operation pressure consumption test
• Water content in gas test

Air circuit breakers - along with vacuum and SF6 circuit breakers - are preferred to oil breakers due to their simpler maintenance requirements.

Vacuum Interruption

Vacuum Circuit breakers extinguish arcs by slightly stretching them. The test for this interrupting mechanism is the hi-pot test. Vacuum circuit breakers remain the most popular choice for MV substation switchgear.

SF6 Interruption

SF6 circuit breakers extinguish arcs by stretching them, at which point the dielectric sulfur hexafluoride completes the process. Tests for the interrupting mechanism are:

• SF6 mixture percentage test
• SF6 by-products test
• Water content in gas test

SF6 circuit breakers are preferred for their arc resistance, heat transfer capability, and the ease with which the SF6 pressure can be monitored.

Call Prime Power for Your Switchgear Testing Needs

For over twenty-five years, Prime Power has performed switchgear breaker testing in the Carolina area for commercial and industrial power users, helping them protect their assets and workers by ensuring that switchgear operates correctly. We also perform:

NFPA 110 generator testing
• Load bank testing
• Healthcare utility management
• Scheduled maintenance
• Arc flash analysis and training
• Modernization and retrofits
• Infrared scanning

If your facility needs breaker testing, do not wait for a fire or catastrophic arc flash to prove the importance of switchgear maintenance. Instead, call Prime Power today for a free consultation.