Description

AVR STAMFORD AS440

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SPECIFICATION INSTALLATION AND ADJUSTMENTS:

AS440 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.

SENSING INPUT:

Voltage Jumper selectable
100-130 Vac 1 phase or
190-264 Vac 1 phase Frequency 50-60 Hz nominal
POWER INPUT
Voltage 100-264 V ac 1 phase Frequency 50-60 Hz nominal

OUTPUT:

Voltage 82 V d.c. @ 200 V a.c.
Current continuous 4A (see note 1). transient 7.5A for 10 secs.
Resistance 15 ohms min (10 ohms min when input volts is less than 175 ac)

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 +/- 1.0%.

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 AVR has the facility for droop CT connection, to allow parallel running with other similarly equipped generators.

REGULATION:

+/- 1.0% (see note 2)

THERMAL DRIFT:

0.03% per deg. C change in AVR ambient (see note 3)

TYPICAL SYSTEM RESPONSE:

AVR response 20 mS
Filed current to 90% 80 mS
Machine Volts to 97% 300 mS

EXTERNAL VOLTAGE ADJUSTMENT:

+/-10% with 1 k ohm 1 watt trimmer (see note 4) Increasing resistance lowers voltage.

UNDER FREQUENCY PROTECTION:

Set point 94 -98% Hz (see note 5)

UNIT POWER DISSIPATION:
12 watts maximum
BUILD UP VOLTAGE:
4 Volts @ AVR terminals
ANALOGUE INPUT:
Maximum input +/- 5 Vdc (see note 6)
Sensitivity 1v for 5% Generator Volts (adjustable) Input resistance 1k ohm
QUADRATURE DROOP INPUT:
10 ohms burden
Max. sensitivity: 0.07 A for 5% droop 0PF Max. input: 0.33 A
OVER EXCITATION PROTECTION:
Set point 75 V dc
Time delay 10-15 seconds (fixed)
ENVIRONMENTAL:
Vibration 20-100 Hz 50mm/sec
100Hz – 2kHz 3.3g
Operating temperature -40 to +70C (note 7)
Relative Humidity 0-70C 95% (note 8)
Storage temperature -55 to +80C

NOTES:
1. De-rate by 12% if mounted in ‘portrait’ orientation.
2. With 4% engine governing.
3. After 2 minutes.
4. Generator de-rate may apply. Check with factory.
5. Factory set, semi-sealed, jumper selectable.
6. Any device connected to the analogue input must be fully floating (galvanically isolated
from ground), with an insulation strength of 500V ac.
7. De-rate output current by 5% per degree C above 60C.
8. Non condensing.