PRISMIC A12
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PRISMIC® A12 Excitation System PRODUCT SPECIFICATION Introduction The PRISMIC® A12 excitation system has been designed to control the excitation of a brushless generator. It incorporates the latest digital micro controller technology to make it the most comprehensive and compact controller available. The PRISMIC® A12 is based upon proven technology and combines the experience and hardware of the BRUSH PRISMIC® A50 excitation controller. It includes, additional features such as intergrated speed detection, power system stabiliser and sychronisation. The PRISMIC® A12 is produced on a plate mounted system either as a single channel or twin channel arrangement. As a twin system each controller acts as a hot standby for the other and is independently controlled with auto tracking, and smooth transfer. An optional colour display screen is also available. Complete excitation system mounted on a plate Available either as a single unit or as a high integrity twin configuration Integrated Power System Stabiliser (optional) Integrated auto synchroniser (optional) Integrated speed detection eliminating need for seperate speed switch Rotor earth fault detector input included eliminating the need for separate unit Negative forcing of exciter field voltage Modes of operation include generator terminal voltage control, power factor control, VAr control and offload VArs Digital Outputs Analogue Input Signal for special application Auxiliary power supply input allows easy setting of unit without PMG supply present Manual Reference Soft start for controlled application of excitation Diode Failure Detection and Indication HMI (Human Machine Interface) software for advanced maintenance diagnostics and downloading of data Oscilloscope style trending and analogue data logging (5ms resolution) via HMI Event Logging Externally mounted display interface computer (Optional) Automatic and manual excitation limiters The following limiters are included: • • • • • • Under Excitation Limiter Over Excitation Limiter Over Flux (V/Hz) Limiter Stator Current Limiter Fast Acting Field Current Limiter Terminal Voltage Limiter Automatic transfer of control to hot standby channel initiated by: • • • • • • Over Voltage Monitor Triggered Under Voltage Monitor Triggered Over Excitation Monitor Triggered Under Excitation Monitor Triggered Over Flux Monitor Triggered Voltage Sensing Error The PRISMIC® A12 includes the following communication port • • • • Limiter and Monitor Settings 1 x RS232 service port 1 x CANbus port for communication with hot standby unit in twin configurations 1 x CANbus port available for connection of display interface computer 1 x RS485 / RS232 Modbus RTU port for SCADA/ DCS communications 1 x PROFIBUS port (optional)

Ratings Max continuous output current: Max 10 second output current: Excitation supply voltage: Excitation supply frequency: Nominal sensing voltage: Auxiliary power supply: Voltage sensing phases: Nominal generator frequency: Current transformer input nominal: Current transformer input burden: Maximum field voltage for forcing: Minimum field voltage: Voltage adjustment range Accuracy of control: Operating temperature range: Storage temperature range: Dimensions Weight: 20A 30A Single phase 85 to 264V 48Hz to 480Hz 100V to 120V 24V d.c. Either 3 phase or 1 phase 50Hz or 60Hz Either 5A or 1A...