Woodward 9907-173 Load Sharing Module

The Woodward 9907-173, also cataloged as the 9907-173 Analog Load Sharing Module, operates as a dedicated hardware component for generator real power measurement and proportional governor biasing within multi-generator paralleling networks. The device processes three-phase potential transformer (PT) and current transformer (CT) voltage and current waveforms to calculate true RMS power parameters, subsequently generating physical correction signals to balance total system kilowatts across parallel-connected prime movers.

Hardware Specifications

Actuator Loop Feedback Response and Dynamics

The Woodward 9907-173 incorporates specialized circuitry designed to optimize the actuator loop feedback response when executing load balancing actions. By establishing a 0-3 VDC isochronous loop line between paralleled units, the module tracks true RMS real power metrics and instantly translates load imbalances into a dynamic bias output. This output alters the governor speed reference circuit to prevent transient oscillations in multi-engine installations. Thermal heat sink dissipation profiles are structured to sustain stable operational characteristics within enclosed switchgear housings from -40 to +70 deg C without external cooling fans. Furthermore, internal electronic dampening provides significant harmonic distortion suppression on the sensing lines, mitigating the corrupting effects of non-linear loads on the generator busbars.

Frequently Asked Questions

Q: How is the primary AC power supply input range configured on the 9907-173 hardware interface?

A: The module accommodates either 95-130 VAC or 190-260 VAC input voltage profiles. Selection between these two distinct working parameters must be executed manually via physical jumper positioning on the terminal block assembly prior to applying line voltage.

Q: What type of signal interface is utilized to send bias commands back to the engine governor?

A: The device yields either a 500 Hz pulse-width modulated (PWM) signal with a 10-90% operational duty cycle or a continuous analog 0-5 VDC correction profile. This provides cross-platform hardware compatibility with legacy Woodward 2301 series governor architectures as well as newer electronic speed controls.

Q: Does the unit support hot-swapping or live replacement while the generator bus is energized?

A: No. The 9907-173 uses direct inline CT (Current Transformer) and PT (Potential Transformer) input terminals. Unplugging or hot-swapping the module while under load will cause an open-circuit condition on active current transformers, generating high voltage spikes that will damage terminal components and present severe hazards to personnel.

Field Installation Guidelines

• Current Transformer Isolation: Ensure all external CT circuits are physically shorted or the generator bus is completely de-energized before terminating or disrupting the CT wiring on terminals to prevent destructive open-circuit voltages.
• Jumper Verification: Verify the correct positioning of the internal voltage-selection jumper (95-130 VAC or 190-260 VAC) matches the local auxiliary utility supply before energizing the module.
• Shielding and Routing: Route all low-voltage analog load-sharing lines (0-3 VDC loop) and governor bias lines using dedicated twisted-pair shielded cables. Keep these cables isolated from high-voltage PT and current-carrying AC lines to prevent magnetic noise coupling.
• Chassis Grounding: Mount the module firmly to the industrial enclosure backing plate using standard mechanical fasteners. Connect a heavy-gauge copper grounding strap from the designated chassis ground terminal to the main station ground busbar.