Less Maintenance

Medium Voltage Air Circuit Breaker Retrofits

Wyle Laboratories has teamed with Siemens to provide economical direct replacements for medium voltage air circuit breakers including the GE Magneblast line. Wyle offers the Siemens 3AFS which uses some of the most advanced vacuum interrupter technology available today and has proven reliable in more than 30,000 installations throughout the world. They are also engineered for long maintenance-free service. The 3AFS vacuum interrupter can withstand 30,000 mechanical operations, 30,000 full current interruptions and up to 100 rated short circuit interruptions. These breakers can be provided using refurbished trucks fitted with vacuum interrupters or all new replacement breakers.

The relative small motion of the 3AFS interrupter is accommodated by a metal bellows which is sealed during manufacturing. There are no leak paths. Siemens vacuum interrupters are conservatively guaranteed for 10 years. However, much longer periods may be expected. Breaking action, even short circuit operations, has no effect on the integrity of the vacuum. Vacuum is the ideal dielectric and the breaking time in a vacuum breaker is extremely low. Therefore, there is no need to generate artificial conditions for arc quenching and contact separation is minimal. All this translates into less required energy storage and a less complicated breaking mechanism than any other type of circuit breaker.

Siemens 3AFS breakers have less than 30 percent as many parts as comparable SF6 and air breakers. Fewer parts with lower energy mechanisms plus totally enclosed breaking contacts mean less maintenance, fewer failures and higher reliability. Mean time to failure (MTTF) has been calculated to be 24,000 years. All Siemens 3AFS breakers have virtually the same operating mechanism regardless of interrupting rating. Therefore, the required inventory of spare parts is further reduced.

Simpler, more reliable mechanisms require less maintenance and are more cost-effective than alternative breakers. Siemens recommends that the 3AFS breaker be lubricated every 10,000 operations or every 10 years and this typically requires less than one hour per breaker. Replacement of vacuum interrupters, closing solenoid, opening solenoid and trip free drive bar mechanism is recommended every 30,000 operations. A major overhaul, if ever required, typically requires less than eight hours.

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