MOTOR BUS TRANSFER
Maintain Plant Process!
Avoid motor damage and costly shutdowns by ensuring the orderly transfer of the sources to your motors. Our complete Motor Bus Transfer System and relays properly execute the transfer of your critical motor loads.
Match the Conditions at the Instant of Transfer—
- Our Motor Bus Transfer System cabinet and loose supplied relays address fast (high-speed synch-check), in-phase (high-speed synchronizing), residual (undervoltage), fixed time transfer and manual transfer applications.
- You can use loose supplied relays or the Motor Bus Transfer System cabinet for specific automatic and manual transfer types.
Enhanced Power Delivery and Safety—
- Dynamically adapts to source conditions, composite motor bus inertia and voltage decay characteristics to automatically determine the best method for transfer— even under adverse fault conditions.
- Mitigate the effects of overvoltage, high volts-per-hertz (overexcitation) and hard loading (mechanical shock) to your motors by assuring source transfer with a minimum of electrical and mechanical stress.
- Avoid needless power plant shutdown due to unavailability of auxiliary services after faulty source transfer.
Motor Bus Transfer System Cabinet
The utility-grade Motor Bus Transfer System Cabinet consists of the M-4272 Digital High Speed Motor Bus Transfer Systems, test switches, control switches, terminal blocks and optional M-3919A Graphic Display Unit / Remote HMI. The system performs all of the necessary logic and control functions for motor bus transfers in two directions by automatically selecting either fast, in-phase or residual voltage transfer methods, according to the bus voltage decay characteristics. The system provides a fast transfer by supervising the delta phase angle and delta frequency between the motor bus and the new source, and blocks a fast transfer if the delta phase angle or delta frequency is excessive. If fast transfer is impossible because of excessive phase angle or delta frequency, the system performs a high-speed synchronizing transfer to close the motor bus in-phase with the new source at the first phase coincidence (first zero crossing). If bus voltage conditions prevent transfer by either method, the system contains a circuit that measures bus voltage, regardless of the frequency, and allows a residual voltage transfer to occur when the motor bus voltage has decayed to a safe level.
In addition to automatic transfer, the system provides manual hot parallel transfer (closed transition / make-before-break transfer) or manual open transition (break-before-make) transfer.