Stamford · Automatic Voltage Regulators
MX321
MX321 Automatic Voltage Regulator
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In short
The MX321 is a PMG-excited automatic voltage regulator with three-phase RMS sensing, offering tighter regulation than the MX341 along with over-excitation protection and provision for parallel operation. It is fitted to larger Stamford HC-series machines.
Fitment
Confirm the frame and winding number against the nameplate before ordering.
| Make | Model / frame | Notes |
|---|---|---|
| Stamford | HC 534 / HC 544 | PMG builds |
| Stamford | HC 634 / HC 644 | — |
| Stamford | P0 / P7 frames | Confirm winding |
Specifications
| Sensing | Three-phase RMS, 190–264 V AC |
|---|---|
| Excitation | PMG, 170–220 V |
| Output | 75 V DC continuous at 4 A |
| Regulation | ±0.5% |
| Protection | Over-excitation, under-frequency |
Cross-references
Equivalent and superseding numbers. Verify against the machine before substituting.
- E000-23414
- MX341
Symptoms that lead here
- Poor voltage regulation on a large PMG set
- Difficulty sharing reactive load in parallel operation
- Exciter overheating
Questions about this part
Does the MX321 support parallel running?
Yes. It provides a quadrature droop input for reactive load sharing between sets running in parallel, which the simpler MX341 does not offer.