With thousands of FSA operating mechanisms in service, ABB is confident that the design is one of the most reliable on the market. The design ensures a high degree of total reliability and minimal need for maintenance for the operating mechanism and, thus, the circuit breaker as a whole.
Applications
The FSA1 spring operating mechanisms are used for the following types of circuit breaker:
Design features
The operating mechanism consists primary of two tension springs. The closing spring generate the required driving force to close the circuit breaker and charge the opening spring. The opening spring is directly connected to the circuit breakers link system. This means that the mechanical energy needed for the vital opening operation is always stored in the opening spring when the circuit breaker is in closed position. In other words, a closed circuit breaker is always prepared for immediate opening.
A universal motor drives the spring charging gear, which automatically charges the closing spring immediately after each closing operation. The springs are kept in charged state by a latch that is released when the circuit breaker is being closed. This enables rapid reclosing of the circuit breaker after a dead time interval of 0.3 s.
Interlocking against unintentional operation
Interlocking is achieved partly electrically and partly mechanically. Electrical interlocking is achieved by having the circuits of the operation coils connected through the auxiliary contacts of the operating mechanism. In addition, the closing coil is connected through a limit switch that is controlled by the position of the spring. In this way the closing circuit is only closed when the breaker is in the open position and the closing springs are fully charged.
Panels
Behind front door (master for single-pole operation SPO) and three-pole operation (TPO) there is a panel that may be equipped differently depending on customer specific requirements. As a standard, the following equipment is included on the control panel:
- Local open/close switch
- Local/remote/disconnect selector switch
- Pole selector switch (only for SPO)
- MCB for motor
- MCB for heater
- Thermostat
- Mechanical operations counter (Visible through an indication window in the cubicle door)
- Mechanical spring charge indicator (Visible through an indication window in the cubicle door)