PRISMIC® A30 Excitation Controller PRODUCT SPECIFICATION Introduction The PRISMIC® A30 excitation controller is designed to control the excitation of a brushless generator. Incorporating a wide range of features, the A30 is housed in a 19” rack assembly requiring only external instruments and control switches to provide the complete excitation system as shown in Fig. 1 below. For commissioning of the A30, a PC is required. PC based software and two serial communications cables are provided. Features Pilot Exciter Brushless Synchronous AC Generator Voltage Transformer The rack incorporates: Instrument Current Transformer Exciter Exciter Field EXTERNAL CONTROLS: Excite/Suppress Main/Standby Selector Set Voltage Datum Set PF/VAr Datum Select PF/VAr/VAr Shed Standby Channel Power supply transformers Power semiconductors Control circuits Excitation changeover contactor Field suppression contactor and resistor Independent Main and Hot Standby Excitation Channels. Main Channel Complete System Housed in a Single 19” 6U rack. Communication Ports for Commissioning & Diagnostics The unit contains two power semiconductor circuits, one acting as a hot standby to the other. Each circuit is controlled by an independent control card with automatic tracking to enable smooth transfer from one to the other. Transfer to the standby system is initiated by a separate monitor module in the following circumstances: • • Voltage monitoring (over/under voltage on generator terminals) Excitation monitoring (over/under excitation with time delays) Monitor Inhibit The settings for the monitor module are selected to enable the normal limiter settings to operate first. EXTERNAL CONNECTIONS: Null Balance Meter (Standby & Auto Matched) (see Fig.2, Generator Capability Diagram, overleaf). PRINCIPAL INDICATIONS: Power Supplies Healthy Individual Monitor Status Individual Limiter Status Diode Failure Alarm PF/VAr/VAr Shed Selected Standby at Minimum Auto/Standby High/Low Main Channel Watchdog Monitor Watchdog Fig 1. A30 Excitation Controller Scheme RELAY CONTACTS: Diode Failure Alarm Limiter Operating Monitor Tripped Field Contactor Closed Main/Standby Selected Auxiliary DC Supply Healthy General Alarm PC-based Setup and Maintenance Software. The unit is provided with PC based setup and maintenance software and cable for connection to a standard PC 9-pin COM port. A PC is required to set up the A30.

Soft Start Facility Under normal operation, as the generator approaches rated speed, the line voltage is increased at an adjustable, controlled rate to the required setpoint. Fast Acting Field Current Limiter Limits excitation current to prevent excessive line current during power system faults. Over Excitation Limiter Using inverse time delay and temperature compensation if required, this facility is provided to prevent overheating of the generator rotor. Fig. 2 Generator Capability Diagram Features (continued) Communication Port #1 for Setup and Maintenance. Provided for connection to an RS232...