SX460 AUTOMATIC VOLTAGE REGULATOR (AVR) SPECIFICATION, INSTALLATION AND ADJUSTMENTS GENERAL DESCRIPTION The SX460 is a half-wave phase-controlled thyristor type Automatic Voltage Regulator (AVR) and forms part of the excitation system for a brushless generator. In addition to regulating the generator voltage, the AVR circuitry includes under-speed and sensing loss protection to ensure safe, reliable control of the generator. Excitation power is derived directly from the generator terminals. Positive voltage build up from residual levels is ensured by the use of efficient semiconductors in the power circuitry of the AVR. The AVR is linked with the main stator windings and the exciter field windings to provide closed loop control of the output voltage with load regulation of +/- 1.5%. In addition to being powered from the main stator, the AVR also derives a sample voltage from the output windings for voltage control purposes. In response to this sample voltage, the AVR controls the power fed to the exciter field, and hence the main field, to maintain the machine output voltage within the specified limits, compensating for load, speed, temperature and power factor of the generator. A frequency measuring circuit continually monitors the generator output and provides output underspeed protection of the excitation system, by reducing the output voltage proportionally with speed below a presettable threshold. A manual adjustment is provided for factory setting of the under frequency roll off point, (UFRO). This can easily be changed to 50 or 60 Hz in the field by push-on wire link selection. Provision is made for the connection of a remote voltage trimmer, allowing the user fine control of the generator's output. TECHNICAL SPECIFICATION INPUT Voltage 85-125 V ac ü ý Jumper Selectable 170-250 V ac þ Frequency 50-60 Hz nominal Phase 1 OUTPUT Voltage max 90 V dc at 207 V ac input Current Continuous 4 A dc Transient 6 A for 10 seconds Field Resistance 15 Ω minimum REGULATION (See Note 1) +/- 1.5% THERMAL DRIFT (after 10 min) 1% for 40°C change in AVR ambient TYPICAL SYSTEM RESPONSE Field current to 90% 80ms Machine Volts to 97% 300ms EXTERNAL VOLTAGE ADJUSTMENT +/- 5% with 1 K Ω trimmer UNDER FREQUENCY PROTECTION Set Point (See Note 2) 95% Hz Slope 170% down to 30 Hz UNIT POWER DISSIPATION 10 watts maximum BUILD UP VOLTAGE 3.5 V ac @ AVR terminals ENVIRONMENTAL Vibration 20-100 Hz 50mm/sec 100 Hz-2 kHz 3.3g Relative Humidity 0-60°C 95% Operating Temperature -40°C to + 70°C Storage Temperature -55°C + 80°C NOTES 1. With 4% engine governing. 2. Factory set, semi-sealed, jumper selectable.