POPULACE
Generator Automatic Voltage Regulator Stamford AVR MX321
Model: Stamford AVR MX321
Compatible MX321 AVR for supported Stamford UC alternators. Check the three-phase PMG supply, sensing arrangement and exact model before ordering.
| Warranty | 13 months |
|---|---|
| Place of Origin | Fujian, China |
| Brand Name | POPULACE |
| Model Number | Stamford AVR MX321 |
| Overall Size | 230×170×55mm |
| Weight | 0.63kg |
| Certification | CE,ISO9001 |
| MOQ | 1 pc |
| Lead time | 2-3 days after payment (in stock), 3-7 days for production batches |
Applications
- Standby and prime diesel generator sets fitted with Stamford alternators in telecom, data-centre and hospital backup power
- Commercial and industrial gensets requiring stable output voltage under varying load
- Alternator rewinds and rebuilds where the original AVR is obsolete or damaged
Product Description
MX321 is a compatible replacement, not an OEM Stamford product. Its technical manual describes a three-phase-sensed AVR supplied from a PMG and notes common use on UC-range alternators including UC22 and UC27. Confirm the alternator model and electrical arrangement before ordering.
General Features
 | Generator Automatic Voltage Regulator Stamford AVR MX321 The MX321 is an analogue, 2-phase sensing, self-excited automatic voltage regulator (AVR). The AVR is linked with the main stator windings and the exciter field windings to provide closed loop control of the output voltage. The MX321 is most commonly used on UC range and are supplied as standard to the UC22 and UC27 alternators. |
 | Features *Sensing input: 190–264 Vac maximum, 2- or 3-phase *50/60 Hz nominal *PMG supply: 170–220 Vac maximum, 3-phase, 3-wire *Output: 120 Vdc maximum; 3.7 A continuous, 6 A intermittent for 10 seconds *Regulation: ±0.5% RMS with 4% engine governing |
| Product Name | Generator AVR MX321 | |
| Sensing/Power input | Voltage | Sensing: 190–264 Vac max, 2- or 3-phase; PMG supply: 170–220 Vac max, 3-phase, 3-wire |
| Frequency | 50–60 Hz nominal | |
| Output | Voltage | 120 Vdc maximum |
| Current | 3.7 A continuous; 6 A intermittent for 10 seconds | |
| Voltage Regulation | ±0.5% RMS with 4% engine governing |
Wiring Diagram
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Stamford SX460 vs MX341 vs AS480: Which AVR Does Your Alternator Really Need? (2026 Engineering Guide)
Selecting between Stamford SX460, MX341, and AS480 AVRs depends on your alternator frame, excitation source (Shunt, PMG, or EBS), and load profile. Here is the full engineering breakdown.
Read Guide → Engineering GuideGenerator AVR Not Producing Voltage: 5 Causes and How to Test Them
A generator that runs but produces no power is most often an excitation or AVR problem. Here are the five causes we see most in the field, the multimeter check for each, and when the regulator itself needs replacing.
Read Guide →FAQ
The MX321 guide describes a three-phase-sensed AVR supplied from a PMG and notes common use on UC-range alternators, including UC22 and UC27. Confirm the exact alternator model, wiring, voltage and excitation arrangement before ordering; send the alternator nameplate and existing AVR label for a setup check.
No. Loss of output can have several causes in the excitation and alternator system. Check the exact alternator manual and wiring diagram before replacing the AVR; a symptom alone does not confirm an AVR fault.
Do not rely on wire colour alone. Use the terminal markings and the wiring diagram for the exact alternator and AVR variant.
Provide the alternator model, load condition, measured voltage and frequency, and the existing AVR label. A speed or frequency change and an AVR sensing/excitation issue require different checks.
Yes. Output voltage, stability adjustment and protection functions are bench-tested on every unit, and the test record travels with your order.
Stamford AVR MX321: overall size 230×170×55mm, shipping weight approx. 0.63kg. Send your panel or packing constraints and we confirm fit.
Stamford AVR MX321 is covered by a 13 months factory warranty. Quality issues within the term are replaced or repaired at our cost.
Stamford AVR MX321 carries CE,ISO9001 certification from our ISO9001-certified Xiamen facility.
Yes. POPULACE Electronic Co., Ltd. manufactures generator parts in Xiamen, Fujian - factory visits are welcome.
This page links a POPULACE compatible-replacement installation guide with technical and wiring information. It is not an original Stamford OEM document; confirm the alternator model and guide revision before using it.
Yes. Samples are available for testing; express freight (FedEx, DHL, UPS, TNT, Aramex) typically delivers within 3-7 days.
T/T, PayPal, Western Union, MoneyGram, Alibaba order link and RMB transfer are all supported.
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