Woodward 9905-792 Speed Control Board

Technical Dossier

Product Details And Specifications

WOODWARD 9905 Series Technical Notes

The WOODWARD 9905 Series represents a mature, field-proven platform deployed across global heavy industry sectors including petrochemical refineries, nuclear power stations, offshore platforms, and large-scale thermal power generation facilities. Originally engineered as a dedicated turbine and generator control system, the 9905 Series established WOODWARD's position as a primary supplier of speed governing and load-sharing control hardware. Installations of this series remain operational across hundreds of baseload power plants in North America, Europe, and Asia-Pacific, where replacement of the control infrastructure is cost-prohibitive. The 9905 architecture is characterized by modular backplane construction, deterministic scan-cycle execution, and hardware-level redundancy options that meet the reliability requirements of continuous-process industries. Its installed base in critical rotating machinery applications — gas turbines, steam turbines, hydro governors, and diesel gensets — makes long-term spare parts availability a primary operational concern for plant maintenance engineers.

9905 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced components within the WOODWARD 9905 Series. Each entry reflects the module's primary functional role within the control system architecture.

9905-792: Speed control board; primary governing processor for turbine speed regulation and droop control.
9905-001: Analog input module; 8-channel, 4–20 mA process signal acquisition for turbine instrumentation.
9905-002: Discrete input module; 16-channel 24 VDC digital input for valve position and limit switch feedback.
9905-003: Discrete output module; 16-channel relay output for actuator command and alarm annunciation.
9905-004: Analog output module; 4-channel 4–20 mA output for valve positioner and speed reference signals.
9905-010: CPU processor board; main control execution unit, hosts application firmware and scan-cycle management.
9905-011: Redundant CPU module; hot-standby processor for bumpless transfer in critical turbine applications.
9905-020: Power supply module; 24 VDC regulated backplane power, 10 A continuous output rating.
9905-021: Redundant power supply; parallel-redundant configuration for uninterrupted backplane voltage.
9905-030: MODBUS RTU communication adapter; RS-485 serial interface for DCS and SCADA data exchange.
9905-031: Ethernet communication module; 10/100 Mbps TCP/IP gateway for plant historian and remote monitoring.
9905-040: Speed/frequency input module; magnetic pickup and proximity probe signal conditioning, dual-channel.
9905-041: Overspeed detection module; hardware-level trip relay, independent of CPU scan cycle, SIL-rated.
9905-050: Load-sharing module; isochronous load sharing across parallel generator sets via droop compensation.
9905-060: Backplane chassis, 8-slot; base mounting rack for 9905 Series module population.
9905-061: Backplane chassis, 16-slot; extended rack for large turbine control configurations.
9905-070: Battery backup module; maintains volatile RAM and real-time clock during power interruption.
9905-080: Thermocouple input module; 8-channel Type K/J/T thermocouple with cold-junction compensation.
9905-090: RTD input module; 4-channel PT100/PT1000 resistance temperature detector signal processing.

Quality Control for the 9905 Range

The WOODWARD 9905 Series employs a proprietary backplane bus architecture with time-multiplexed data transfer between the CPU and I/O modules. Standard incoming inspection procedures at DriveKNMS include visual inspection for physical damage, corrosion, and component substitution; powered functional testing on a dedicated 9905 test chassis replicating the original backplane electrical environment; firmware version verification against the customer's installed revision; and burn-in testing under simulated load conditions for a minimum of 24 hours. Speed control boards such as the 9905-792 undergo additional validation: magnetic pickup signal simulation across the full operating frequency range (0–10,000 Hz), actuator output linearity verification, and overspeed trip relay response-time measurement. Communication modules are tested for protocol compliance using MODBUS master simulation tools. All units that pass the full test protocol are issued a DriveKNMS test certificate with recorded test parameters and technician sign-off.