Overview
The KRS440B 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
- High Current Output — 16A continuous rating for large alternator excitation
- Wide Sensing Range — 170-264VAC or 352-528VAC selectable input
- Solid-State Design — Reliable thyristor-based regulation for industrial environments
- Stable Voltage Control — Maintains consistent output under varying load conditions
- Direct OEM Replacement — Drop-in compatible with Stamford alternator systems
Technical Specifications
| Parameter | Value |
|---|---|
| Sensing Input | 100-130VAC or 170-264VAC, 2-phase |
| Power Input | 100-264VAC, 1-phase |
| Output Voltage | Max 82VDC at 200VAC input |
| Output Current | Continuous 4A, Intermittent 7.5A for 10s |
| Regulation Accuracy | <±1.0% (with 4% engine governing) |
| Frequency | 50-60Hz (universal) |
| UF Protection | 92%-94% of rated frequency |
| Excitation Type | Self-excited shunt |
| Soft Start | Yes (3 sec ramp) |
| Thermal Drift | 0.02%/°C |
| Operating Temp | -40°C to +70°C |
Compatibility
- Stamford Large Frame Alternators
- High-power generator applications
- Compatible with: Part.: KRS440B
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 compatible replacement, 50-200kW brushless generators.
Competitors SX440 (Stamford OEM), SX460 (Stamford entry-level).
| Parameter | KRS440B | SX440 | SX460 |
| Brand | KERUI (China) | Stamford (UK) | Stamford (UK) |
| Output Current | 4A | 4A | 4A |
| Regulation | ±1% | ±1% | ±1% |
| PMG Support | Yes | Yes | No |
| Quality Consistency | Moderate (batch variation) | High | High |
| Price | $15-25 | $40-60 | $25-45 |
Selection Advice
The KRS440B is a Chinese KERUI compatible product based on the SX440 circuit design, priced at approximately 1/3 to 1/2 of the OEM. Nominal specifications match the SX440 exactly. However, customers should be informed: domestic compatible product component quality control and factory testing standards are not as rigorous as Stamford OEM, batch-to-batch consistency varies, and long-term reliability has not been market-validated for 10+ years. Suitable for price-sensitive customers where the generator serves non-critical applications (temporary construction site power, agricultural irrigation, small shop backup). Not recommended for hospitals, data centers, or communication base stations requiring high power reliability.
