Overview
The MX342 is an Automatic Voltage Regulator (AVR) that maintains the generator output voltage within precise limits by controlling the exciter field current. It continuously samples the generator output voltage and adjusts excitation to compensate for load changes, engine speed variations, and temperature drift.
Key Features
- 2-Phase Sensing — Superior motor starting and load sharing
- PMG-Powered — Isolated from non-linear load effects
- 2.7A Continuous / 6A Intermittent — 120VDC max output
- ±1% Regulation — With 4% engine governing
- Current Limiting — Stator current limit input for overload protection
- Droop CT Input — Parallel operation capable
- Analogue Input — For PF controller or external voltage trim
- Soft Start & UF Protection — 3-sec ramp, 59.5Hz default set point
Technical Specifications
| Parameter | Value |
|---|---|
| Type | 2-phase sensing, PMG-powered, analogue AVR |
| Sensing Input | 190-264VAC, 1-phase, 2-wire |
| Power Input (PMG) | 170-220VAC, 3-phase, 3-wire, 3A/phase, 100-120Hz |
| Output Voltage | Max 120VDC |
| Output Current | Continuous 2.7A, Intermittent 6A for 10s |
| Min Field Resistance | 15 ohms |
| Regulation Accuracy | <±1% (with 4% engine governing) |
| Soft Start | 3 seconds ramp |
| UF Protection | Set point 59.5Hz (user adjustable), linear down to 18Hz |
| Overexcitation Shutdown | 75VDC, 10s delay |
| Droop CT Input | Yes (for parallel operation) |
| Current Limit Input | Yes (stator current limiting) |
| Analogue Input | ±5VDC for PF controller/external devices |
| Operating Temp | -40°C to +70°C |
Compatibility
Stamford alternators. Compatible with: MX342.
Why Choose ZenixPower
- Tight Voltage Regulation — <±1% RMS regulation ensures stable generator output under 0-100% load transients
- Fast Response — Sub-0.5 second recovery time prevents voltage dips during motor starting and load switching
- Dual Excitation Compatibility — Self-excited shunt or PMG-powered configurations clearly labeled for correct selection
- Built-in Protections — Under-frequency roll-off, over-excitation limiting, and soft-start ramp as standard
- Drop-In Replacement — Terminal layout and mounting dimensions match STAMFORD, Leroy-Somer, Marathon, and Mecc Alte OEM AVRs
- Pre-Calibrated — Each AVR ships with factory-default potentiometer settings for immediate plug-and-play operation
Specification Comparison
Compatible Generators Stamford HC/LC 100-500kW, especially suitable for generators with aging field windings or overload risk.
Competitors MX341 (Stamford standard), R250 (Leroy Somer).
| Parameter | MX342 | MX341 | R250 |
| Current Limiting | Yes | No | No |
| Regulation | ±1% | ±0.5% | ±0.5% |
| Output Current | 4A | 4A | 5A |
| Price | $55-85 | $50-80 | $110-190 |
Selection Advice The MX342 adds only one feature over the MX341 — current limiting. This function is valuable when generator field windings have aged, insulation has degraded, or the generator is prone to overload conditions. If a customer’s older generator has a history of AVR burnout, switching to the MX342 can extend service life through current limiting protection. If the generator is in good condition, the MX341 is sufficient and less expensive.
