1.Introduction:
Stamford AS440 AVR is a half wave phase controlled thyristor type AVR and forms part of the
excitation system for a brush-less generator. The design employs Surface Mount Technology (SMT)
for high integration of features in a small footprint AVR.
Positive voltage build up from residual levels is ensured by the use of efficient semiconductors in the
power circuitry of the AVR. The power and voltage sensing circuits have separate terminals, allowing
the excitation power to be derived directly from the stator winding for basic applications or from an
auxiliary winding if sustained short circuit performance is required.
The AS440 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 +/- 1.0%.
The AVR voltage sensing terminals continuously sample 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 under-speed protection
of the excitation system, by reducing the output voltage proportionally with speed below a pre-settable 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 link selection.
Over excitation conditions are limited to a safe period by a protection circuit within the AVR.
Provision is made for the connection of a remote voltage trimmer, allowing the user fine control of the
generator's output.
An analogue input is provided allowing connection to a Newage Power Factor controller or other external
devices with compatible output.
The Stamford AVR AS440 Voltage Regulator has the facility for droop CT connection, to allow parallel
running with other similarly equipped generators.
2.Technical data:
| Technical specification |
| Sening input |
| Voltage | Jumper selectable 100-130V ac 1 phase or 190-264V ac 1 phase |
| Frenquency | 50-60Hz nominal |
| Power input | |
| Voltage | 100-264V ac 1 phase |
| Frequency | 50-60Hz nominal |
| Output | |
| Voltage | 82V dc @200V ac |
| Current | continuous 4A transient 7.5A for 10 secs |
| Resistance | 15 ohms min (10 ohms min when input volts i s less than 175ac) |
| Regulation | +/-1.0% |
