The Woodward 9907-173, also cataloged as the 9907-173 Load Sharing Module, operates as a dedicated hardware component for isochronous and droop load balancing within parallel generator control systems. The module senses 3-phase potential transformer (PT) and current transformer (CT) signals from generator buses, generating a +/-3 VDC analog bias output signal to modulate speed governors and balance active real power distribution across multiple paralleled prime movers.

Hardware Specifications

Actuator Loop Feedback Response & Power Balancing

The Woodward 9907-173 computes total generator active power by processing instantaneous line voltage and current transformer inputs across a 50 Hz to 400 Hz frequency range. Internal analog control loops dynamically calculate load differentials relative to the paralleling bus, adjusting the +/-3 VDC output to optimize actuator loop feedback response. This direct speed control biasing maintains tight power balance during load step transients without introducing system oscillation.

Frequently Asked Questions

Q: How is the power supply voltage range configured on the Woodward 9907-173 module?

A: Terminal connections allow field selection between 115 VAC nominal (95-130 VAC operating band) and 230 VAC nominal (190-260 VAC operating band) power inputs across a 50 Hz to 400 Hz frequency spectrum.

Q: What are the primary sensing transformer ratings required for proper operation?

A: The sensing stage accepts 3-phase line-to-line PT inputs between 100 VAC and 240 VAC, paired with 3-phase CT secondary current inputs rated for 3 Arms to 7 Arms at maximum generator output.

Q: What range of droop speed regulation is supported when operating in droop mode?

A: The integrated droop potentiometer circuitry allows adjustment of generator speed reduction from 0% (isochronous operation) up to a maximum 10% speed droop for parallel utility grid operation.

Field Installation Guidelines

• Verify that all AC power supplies, PT lines, and CT circuits are de-energized and safely isolated prior to landing terminal wiring.
• Connect CT secondary lines through dedicated shorting blocks to ensure current transformers remain shorted during maintenance or installation.
• Route analog signal output wiring and load sharing bus lines using twisted shielded-pair cable separate from AC power and high-voltage supply lines.
• Terminate cable shields at the panel earth grounding point only to avoid ground loop noise on the +/-3 VDC analog output loop.
• Secure the chassis to the mounting panel using hardware with a minimum of 5-turn thread engagement to maintain physical stability under 40 g shock conditions.