Allis Chalmers and Siemens 5Kv and 15Kv Circuit Breakers
Early 5 Kv and 15 Kv Allis Chalmers were vertical lift air breakers that had 6 stabs that went out the top of the circuit breaker. These early am breakers required a lifting mechanism in the cell, to lock them on to. The primary disconnects of the switchgear. early vintages were AM-50-600 amp, AM-75, AM-150 A, B, C, D, and AM-250 A, B, C, D.
The Allis Chalmers breakers manufactured in the late 1950’s became horizontal draw out air breakers. This made them much more reliable to rack in and out of switchgear. Allis Chalmers circuit breakers became Siemens Allis circuit breakers and models for 5kv and 15 Kv were as follows: MA250, MA-250B, MA-250C, MA-250C1.
15 Kv Siemens Allis breakers were FC-500, FC-500A, FC-500A1, and FC-500B, FC-750 A1, and FC-1000B. These breakers; 5Kv and 15 Kv were manufactured in 1200 amp, 2000 amp and 3000 amp. Siemens Allis produced two generations of vacuum circuit breakers beginning in the late 1970’s to the early 1980’s.
The earlier generation being in 5Kv, 5-3AF-250, 5-3AF-350, and 15 Kv Siemens vacuum breakers were 15-3AF-500. The 3 AF was followed by the Siemens Allis GMI vacuum breaker. Types were: 5-GMI-250, 5-GMI-350, 15-GMI-500, 15-GMI-750, and 15-GMI-1000.