The WOODWARD 9905-001 is an analog Speed and Phase Matching (SPM-A) synchronizer designed for use with engines or turbines equipped with Woodward speed controls. This unit provides automated frequency and phase matching by generating a proportional bias signal to the governor, allowing for a seamless, bumpless closure of the generator breaker onto the bus. It is specifically engineered for systems that require a high degree of stability during the synchronization process to prevent mechanical shock to the prime mover.
Product Specifications
| Parameter | Specification |
| Model Number | 9905-001 |
| Control Type | Analog SPM-A (Speed and Phase Matching) |
| Input Voltage | 115 Vac (Nominal), 50/60 Hz |
| Input Range | 95–130 Vac |
| Power Consumption | 5 W Maximum |
| Phase Offset | Adjustable 0 to ±10 degrees |
| Frequency Window | Adjustable 0.1 to 1.0 Hz |
| Output Signal | Analog bias signal (to speed control) |
| Operating Temp | -40°C to +70°C |
| Enclosure | Back-panel mount, NEMA 1 equivalent |
The Woodward 9905-001 acts as the intelligent bridge between the generator and the utility bus, monitoring the voltage waveforms of both sources to calculate the exact moment for breaker engagement. Its specialized circuitry filters out harmonic noise on the sensing lines, ensuring that the bias signal sent to the governor is smooth and responsive. This prevents the “hunting” behavior often seen in lower-quality synchronizers, making it a reliable choice for critical power applications where grid-parallel stability is paramount.
Woodward 9905-001 SPM-A Synchronizer
Model Comparison: 9905-001 vs. 9907 Series
The 9905-001 is a foundational model within the SPM-A family, primarily differing from the 9907-028 in its input voltage configuration and output drive capability. While many 9907 variants offer selectable dual-voltage inputs (115/230 Vac), the 9905-001 is typically optimized for 115 Vac sensing environments. Furthermore, the 9905-001 is designed to interface with legacy analog load sharing and speed control modules, whereas newer 9907 revisions may include hardware enhancements for improved noise rejection and slightly different potentiometer adjustment ranges for the “Sync-Check” window.
Operation Tips
- Potentiometer Calibration: Carefully adjust the “Phase Window” and “Time Delay” potentiometers to match the specific closing speed of your circuit breaker; a window set too narrow may cause the synchronizer to “miss” its window if the breaker mechanics are sluggish.
- Sensing Transformer Polarity: Ensure that the potential transformers (PTs) for both the bus and the generator are wired with the same polarity; reversed polarity will cause the 9905-001 to sense a 180-degree phase shift, preventing synchronization.
- Bias Signal Compatibility: Verify that the output bias signal is compatible with your governor’s auxiliary input (e.g., ±3 Vdc or 0.5–4.5 Vdc); improper impedance matching can result in sluggish frequency correction.
- Grounding Practices: To avoid signal interference, ensure the synchronizer chassis is grounded to the same potential as the governor control, and use shielded wiring for the sensing leads.
