The MX321 analogue, 3-phase sensing, permanent magnet generator (PMG) powered automatic voltage regulator (AVR) provides isolation from the effects of non-linear loads, improved motor starting performance and sustained short circuit current.

The MX321 AVR is provided as standard for the STAMFORD S6 and HC6 alternators and can also be provided as an option across the STAMFORD range.

Technical specification:

SENSING INPUT

• Voltage: 190-264V ac max, 2 or 3 phase

• Frequency: 50-60 Hz nominal

POWER INPUT (PMG)

• Voltage: 170-220V ac max, 3 phase, 3 wire

• Current: 3A/phase

• Frequency: 100-120 Hz nominal

OUTPUT

• Voltage: max 120V dc

• Current: continuous 3.7 A, Intermittent 6A for 10 secs

• Resistance: 15 ohms minimum

REGULATION

• +/- 0.5% RMS with 4% engine governing

THERMAL DRIFT

• 0.02% per deg. C change in AVR ambient

SOFT START RAMP TIME 

• 0.4 - 4 seconds

TYPICAL SYSTEM RESPONSE

• AVR response: 10 ms

• Filed current to 90%: 80 ms

• Machine Volts to 97%: 300 ms

EXTERNAL VOLTAGE ADJUSTMENT

• +/-10% with 5 k ohm 1 watt trimmer

UNDER FREQUENCY PROTECTION

• Set point: 94-98% Hz

• Slope 100-300% down to 30 Hz

• Max. Dwell 20% volts/S recovery

UNIT POWER DISSIPATION

• 18 watts maximum

ANALOGUE INPUT 

• Maximum input +/- 5 Vdc

• Sensitivity 1v for 5% Generator Volts (adjustable)

• Input resistance 1k ohm

QUADRATURE DROOP INPUT 

• 10 ohms burden

• Max. sensitivity: 0.22 A for 5% droop 0PF

• Max. input: 0.33 A

CURRENT LIMIT INPUT 

• 10 ohms burden

• Sensitivity range: 0.5 – 1A

OVER VOLTAGE DETECTOR INPUT 

• Set point: 300v. Time delay: 1 Sec (fixed)

• CB trip coil volts: 10-30 vdc

• CB trip coil resistance: 20-60 ohms

OVER EXCITATION PROTECTION 

• Set point 75 V dc Time delay 8-15 seconds (fixed)

• Time delay 8-15 seconds (fixed)

ENVIRONMENTAL

• Vibration: 20-100 Hz 50mm/sec

                  100Hz – 2kHz 3.3g

• Operating temperature: -40 to +70°C

• Relative Humidity: 0-70°C 95%  

• Storage temperature: -55 to +80°C

NOTES

1) Derate linearly from 3.7A at 50°C to 2.7A at 70°C;

2) The stated voltage regulation may not be maintained in the presence of certain transmitted radio signals. Any change in regulation will fall within the limits in Criteria B of BS.EN.61000-6-2: 2001;

3) After 10 minutes;

4) Applies to Mod status E onwards. 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) Non condensing.