A breaker nameplate normally identifies the breaker type, rated voltage, continuous current, frequency, interrupting rating, control voltage and serial number.

Record the information exactly as shown. Don’t shorten the model number or assume that one portion of the designation provides everything needed for a replacement.

Clear photographs of the nameplate, breaker, disconnects and mechanism are also helpful, especially when identification plates are damaged or difficult to read.

Begin with the nameplate rather than relying on the breaker’s appearance.

In the GE Power/Vac VB1 4.16-350, 2000A example, 2000A identifies the continuous-current rating. The 4.16-350 portion is part of the breaker’s rating-class designation. Because legacy nomenclature may reflect older rating conventions, don’t convert it into a modern interrupting-current value without checking the nameplate and technical documentation.

The mechanism supplies the energy needed to close and open the breaker contacts. It includes components like spring charging, closing, tripping and latching.

Power/Vac breakers may use mechanisms like ML-18 or ML-18H. When requesting a replacement vacuum circuit breaker, provide mechanism details and the breaker model and ratings.

ML-18 and ML-18H are related GE stored-energy mechanisms used with certain Power/Vac breakers, but they shouldn’t be considered interchangeable.

Their applications, construction and components can differ. These differences affect replacement parts, adjustments and compatibility with a breaker frame.

Voltage and current ratings don’t give you complete medium-voltage breaker compatibility. A replacement must also match or properly coordinate with the existing:

• Interrupting rating
• Control voltage
• Primary and secondary disconnects
• Racking mechanism
• Interlocks
• Closing and tripping circuits

A breaker selected only by voltage and amperage may not rack into the cell, connect to the control circuit or operate with the switchgear’s safety features.

The cell is essentially an isolated enclosure for the breaker. Confirm switchgear-cell compatibility by comparing the replacement breaker with the original breaker and compartment.

Provide the breaker and switchgear nameplates, model and serial numbers, equipment drawings and photographs of the breaker, disconnects and cell.

The primary disconnects carry power between the breaker and switchgear. Their spacing, dimensions and contact arrangement must match the cell.

The secondary disconnect connects the closing, tripping, indication and control circuits. Its configuration and wiring must also be compatible.

Interlocks may prevent the breaker from moving while closed or closing in an incorrect position. These safety features shouldn’t be bypassed to make a breaker fit.

Reconditioning may be sufficient when the breaker frame, interrupters, mechanism and major components remain serviceable.

A direct replacement applies when the original breaker is damaged or expensive to repair. An engineered retrofit lets you stay with the existing switchgear while installing a different breaker design, reducing expense.

If the lineup has extensive insulation, bus or control-system problems, modernization makes sense. BCS also designs custom switchgear for facility power distribution when replacing one breaker won’t get you back online.

Provide the following information:

• Complete breaker model and serial number
• Rated voltage and continuous current
• Interrupting rating
• Closing and tripping voltages
• Mechanism designation
• Switchgear manufacturer and lineup information
• Breaker and cell photographs
• Available drawings or schematics

Also tell your switchgear service provider if you’re replacing a failed breaker, purchasing a spare or planning a Power/Vac switchgear modernization project.