Woodward 9905-971 Discrete Input Module

Configured for high-speed state monitoring in turbine control platforms, the Woodward 9905-971 (9905-971 Discrete Input Module) provides direct physical/electrical execution of 24 VDC contact signal acquisition.

Suffix Breakdown & Model Matrix

The 9905-971 operates as a standardized discrete input interface within the Woodward control chassis. This model is categorized as a 24-channel discrete input module featuring an update time of 5 ms and a time-stamping resolution of 1 ms. No alternate hardware revisions or functional sub-variants are defined for this specific catalog number; the unit is configured as a singular hardware assembly for integration into chassis card guides.

Hardware Specifications

V/Hz and Field-Oriented Vector Control

The 9905-971 provides the critical status feedback necessary for the execution of V/Hz and field-oriented vector control algorithms. By capturing discrete state changes with a 1 ms resolution, the module ensures that the governing system maintains precise synchronization with external turbine valve feedback and auxiliary contact positions. The integration of latent fault detection within the discrete input logic permits the monitoring system to distinguish between intended contact states and hardware-level malfunctions, thereby maintaining the integrity of the control loop feedback response during dynamic operational transients.

Frequently Asked Questions

Q: Are the discrete input channels galvanically isolated?

A: Yes, all discrete inputs are fully isolated. A common reference point must be established between the inputs and the external contact power source to ensure proper signal referencing.

Q: What are the requirements for using the internal vs. external power source for contact wetting?

A: If the internal 24 VDC power source is used, jumpers must be installed between module terminals 33, 34, and 35. When utilizing an external power source (18-32 VDC or 100-150 VDC), the common of the external source must be connected to terminals 34 and 35.

Field Installation Guidelines

1. Chassis Insertion: Align the module with the chassis card guides. Slide the module in until the edge connector makes full contact with the motherboard.
2. Mechanical Security: Secure the front panel to the chassis using the top and bottom mounting screws to prevent vibration-induced disconnection.
3. Common Referencing: Ensure the discrete input common (terminals 34 and 35) is appropriately referenced to the contact wetting power source to prevent floating input signals.
4. Wiring Termination: Verify all field wiring connections for tightness. For 24 VDC contact wetting, ensure required terminal jumpers are installed to bridge the internal supply.
5. Extraction: To remove, toggle the top and bottom handles outward to disengage the board from the motherboard connectors before sliding the module out of the chassis.