McPherson Controls | Voltage Regulator | SS321

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McPherson Controls | Voltage Regulator | SS321


  • Replacement for Newage MX321 and Onan 305-0823 
  • McPherson Controls Self Excited Automatic Voltage Regulator  
  • 3 Phase Sensing Permanent Magnet Generator type AVR 
  • Not a genuine Newage or Onan product 

Available on backorder. Usually ships in 3 to 5 business days.

can be export

Product can be export to the Caribbean, Latin America and other parts of the world with an additional payment.

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SKU: SS321
Additional Info


Details and Specifications

  • Voltage regulation less than +/-0.5% RMS 
  • For use in parallel operation 
  • RAMP, DIP, DWELL, DROOP, RMS, U/F, Over Voltage and Over Excitation Adjustment Functions 
  • Over Exc. / Over Volt. and UFRO LED indicators 
  • Current limiting function 

Product Specifications:

Sensing Input Voltage 190 to 264 Vac 3 phase 

Frequency 50/60 Hz selectable 

Power Input (PMG) Voltage 170 to 220 Vac 3 phase 3 wire 

Current 3A / phase 

Frequency 100 to 120 Hz nominal 

Excitation Output Voltage Max. 120 Vdc @ power input 220 Vac 

Current Continuous 4A Intermittent 7A for 60 seconds 

Resistance Min. 15 ohms 

External Voltage Adjustment Max. +/-10% @ 5K ohms 1 watt potentiometer 
Voltage Regulation Less than +/-0.5% RMS (with 4% engine governing) 
Build Up Voltage 5Vac residual volts at power input terminal 
Soft Start Ramp Time 0.4 to 4 seconds 
Static Power Dissipation Max. 18 watts 
Quadrature Droop Input Burden 10 ohms 

Max. Input 0.33A 

Max. Sensitivity 0.22A for 5% droop (PF=0) 

Analogue Voltage Input Input Resistance 1K ohm 

Max. Input +/-5 Vdc 

Sensitivity 1V for 5% generator volt 

Over Voltage Detector Input Set Point 300V 

Time Delay 1 second (fixed) 

CB trip coil volt 10 to 30 Vdc / 0.5 Amp 

Current Limit Input Burden 10 ohms 

Sensitivity Range 0.5A to 1A 

Under Frequency Protection (Factory Presets) Set Point 95% Hz 

Slope 100 to 300% down to 30 Hz 

Over Excitation Protection Set Point 120 Vdc 

Time Delay 8 to 15 seconds 

Voltage Thermal Drift Less than 5% at temperature range -40 to +70 °C 


AVR Control Functions 
VOLT Voltage adjustment 
STAB Stability adjustment 
UFRO Setting under frequency protection knee point 
DROOP To set the Droop to 5% at PF=0 
TRIM To optimize analogue input sensitivity 
EXC TRIP Over excitation trip level set 
DIP Hz related voltage DIP set 
DWELL Hz related recovery time set 
I/LIMIT Stator current limit set 
OVER/V Over voltage trip level set 
RAMP No load voltage Ramp set time 
RMS Root mean square of generator 


Operating Temperature -40 to +70 °C 
Storage Temperature -40 to +85 °C 
Relative Humidity Max. 95% 
Vibration 3.3 Gs @ 100 to 2K Hz 


Physical Specifications 
Dimensions 203.5 (L) x 153.6 (W) x 43.5 (H) mm 
Weight 530 g +/-2% 

PRODUCT Related documents:

SS321 Manual

Additional Info
Weight2 lbs
Dimensions9 × 6.5 × 2.25 in


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