Woodward 8440-1706 Digital Synchronizer for Generators

The Woodward 8440-1706 Digital Synchronizer for Generators is a microprocessor-based synchronizing unit with integrated load sharing and power control functions for three-phase (and single-phase) AC generators. It automatically matches frequency, phase angle, and voltage of the generator to the bus, controls one power circuit breaker, and provides active/reactive load sharing plus generator protection — compatible with Woodward or other speed governors and voltage regulators.

Key Features

• Automatic frequency, phase-angle, and voltage matching via analog or discrete bias outputs
• Synchronizing and synch-check for one power circuit breaker
• Integrated active power (load) control and load sharing between parallel generators
• Reactive power (var) control and var sharing; power factor control
• Soft unloading and dead-bus start functionality (per configured package)
• Generator protection functions with power limit values and relay outputs
• True-RMS power measurement; generator power setpoints via parameters or 0/4–20 mA
• Microprocessor-based, field-configurable via parameters
• Works with Woodward or third-party governors and AVRs

Technical Specifications

• Part Number: 8440-1706 (SPM-D11 series)
• Product Type: Digital synchronizer / synchronizing unit with load sharing
• Measuring Voltage: Rated 230/400 V AC; max 300 V AC
• Measuring Frequency: 40.0–70.0 Hz (50/60 Hz systems)
• Power Supply: 12/24 V DC (9.5–32 V DC) or 90–250 V AC / 120–375 V DC
• Accuracy: Class 1
• Surge Withstand: 2.5 kV / 4.0 kV
• Load Sharing Interface: 0–4 V DC (load) / 0–4 V DC (var) sharing lines
• Bias Outputs (LSXR package): Freely configurable analog levels: ±1 V, ±3 V, 0–5 V, 0.5–4.5 V, ±5 V, ±10 V, 0–20 mA, ±20 mA, etc.
• Inputs/Outputs: Discrete inputs for synchronizing logic; relay outputs for breaker and alarm control
• System: Single-phase or three-phase AC generator sets
• Origin: United States

Installation Notes

1. Verify the SPM-D11 configuration package and supply version against the 8440-1706 part number before installation.
2. Connect the generator and bus voltage/current transformers per the wiring diagram (three-phase or single-phase per configuration); observe correct phase sequence.
3. Apply the correct power supply (12/24 V DC or AC/DC version per nameplate); fuse and protect per manual.
4. For load sharing, interconnect the load-sharing (terminal 29) and var-sharing (terminal 30) lines between paralleled units.
5. Configure parameters (sync window, voltage/frequency matching, power setpoints) via the front panel / software per manual 37259; verify synch-check before closing the breaker.

Common Questions

What does the SPM-D11 do? It synchronizes a generator to the bus (voltage, frequency, phase matching), closes the generator breaker, and then controls active/reactive power with load sharing when running in parallel — plus generator protection.

What is the difference between SPM-D10, SPM-D11, and SPM-D21? Per Woodward: the SPM-D10 is a three-phase synchronizer with dead-bus start logic; the SPM-D11 adds load sharing; the SPM-D21 adds two-breaker synchronizing and load control.

What power supply does the 8440-1706 need? 12/24 V DC (9.5–32 V DC) or 90–250 V AC / 120–375 V DC depending on the supply version — check the unit nameplate.

Which generators can it control? Three-phase or single-phase AC generators with Woodward or compatible speed governors and automatic voltage regulators.