WOODWARD 9905‑373 Digital Synchronizing & Load Controller
1. Product Information
The WOODWARD 9905‑373 is a fully‑featured upgraded digital synchronizing and load controller of the DSLC series. It adopts open‑delta PT voltage sampling configuration and delivers 500 Hz PWM speed bias output. Integrating synchronizing & paralleling, load measurement, active/reactive load sharing, dead‑bus closing and process power management into one unit, it is designed for three‑phase AC generator sets paired with Woodward governors and automatic voltage regulators (AVR).
The 9905‑373 realizes peer‑to‑peer load sharing among multiple generator units via LON digital local area network. It supports two operating modes: island bus operation and utility parallel operation. True‑RMS three‑phase sampling guarantees control accuracy under unbalanced‑load and waveform‑distortion conditions. All parameter configuration and fault troubleshooting can be performed with the 9907‑205 hand‑held programmer. Dead‑bus closing logic is implemented without an external PLC, which greatly simplifies the engineering design of low‑voltage paralleling cabinets. It serves as a mainstream control unit for marine power stations, standby generator sets and industrial captive power plants. As a full‑featured DSLC variant, the 9905‑373 fully covers control requirements for reactive power, power factor and process inlet‑outlet power, overcoming functional limitations of streamlined DSLC models.
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Core Technical Specifications
Environmental Parameters
Operating temperature: ‑40℃ ~ +70℃; Storage temperature: ‑55℃ ~ +105℃; Maximum ambient humidity 95% non‑condensing at 38℃; Electromagnetic compatibility complies with ANSI/IEEE C37.90.2 and ANSI C37.90.1‑1989; Mechanical shock meets MIL‑STD 810C; Vibration complies with MIL‑STD 167 Class I.
Power & Electrical Parameters
Continuous control power supply: 8‑32 VDC; Short‑term maximum 77 VDC for 5‑minute duration; Continuous reverse withstand voltage: ‑56 VDC; Total unit power consumption: 18 W; Maximum operating current: 1 A.
Voltage sampling: 120 Vac open‑delta PT configuration, input range 65‑150 Vac, applicable frequency 45‑66 Hz; per‑phase power consumption below 0.1 VA; full‑scale measurement accuracy 0.1%.
Current transformer input: 0‑5 AAC, short‑term peak 7 A, 45‑66 Hz; per‑channel power consumption ＜0.1 VA; measurement accuracy 0.1%.
Digital inputs: 18‑40 VDC, 10 mA per channel. Analog inputs: 4‑20 mA (243Ω) / 1‑5 VDC (10 kΩ).
Analog outputs: 500 Hz PWM speed bias signal; high‑channel voltage bias ±9 V, low‑channel voltage bias ±3 V; output current 50 mA.
Relay driver outputs: 18‑40 VDC, sink current 200 mA.
Communication interfaces: LONWORKS local area network at 1.25 Mbps; RS‑422 port for calibration and diagnosis.
Model‑Specific Parameters
WOODWARD 9905‑373 is a fully‑featured upgraded unit with 120 V open‑delta PT and 500 Hz PWM speed bias output. Overall dimensions: 460.5 mm × 264.16 mm × 58.55 mm; approximate unit weight 3.1 kg; UL and cUL safety certifications obtained.
Core Features
Dual‑architecture operation modes: island‑bus mode and utility‑parallel mode. Automatic mode switching comes with adaptive reactive‑power control logic; manual locking of VAR / power‑factor regulation mode is also available.
Synchronization function supports two paralleling logics: phase‑matching and slip‑frequency synchronization. It coordinates with the AVR regulator to complete voltage‑amplitude matching prior to grid‑closure for minimized paralleling transients.
Dual‑mode reactive‑power control: fixed reactive‑power output and constant power‑factor control. Reactive load is equally shared among multiple units in island‑mode systems via the LON network.
Process power management: remote set‑points for import‑export power are given through analog signals. Combined with the MSLC master synchronizing controller, it realizes plant‑wide total load management.
Comprehensive hardware I/O configuration: multiple isolated digital inputs collect circuit‑breaker auxiliary contacts and close‑permit signals; relay outputs govern breaker closing, voltage raise/lower, load increase/decrease and fault alarms; multiple isolated analog outputs interface with governors and AVR automatic voltage regulators.
Standard certifications: UL/cUL listed certification meets compliance requirements for complete generator‑set export projects. Wide‑range temperature and voltage tolerance enables reliable performance under harsh conditions such as marine vessels and field power stations.
Hardware expansion compatibility: The WOODWARD 9905‑373 can work in conjunction with MSLC master controllers, 723PLUS gateways and LSIM load‑sharing interface modules to construct large‑scale multi‑unit parallel power‑station systems.
Application Fields
Industrial captive diesel / gas generator‑sets: factory backup power and peak‑shaving power stations for multi‑unit island parallel operation and load management under utility grid‑tied conditions.
Marine power systems: multi‑generator paralleling for merchant ships and engineering vessels, covering dead‑bus closing and load sharing during navigation.
Field power stations for oil & gas fields: stable synchronizing control for mobile generator‑sets under wide‑temperature and wide‑voltage operating environments.
Backup power for buildings and data centers: redundant parallel operation of multiple units with seamless switchover to island‑mode upon utility power failure.
Small‑scale combined heat and power (CHP) units: grid‑connection with constant power‑factor and precise import‑export process power management.
Legacy power‑station retrofitting projects: the WOODWARD 9905‑373 is compatible with conventional analog governors. It replaces old discrete synchronizers and load‑sharing modules and simplifies rewiring during renovation.
FAQ
Q1: What is the core difference between WOODWARD 9905‑373 and the streamlined DSLC version?A1: The WOODWARD 9905‑373 is a fully‑featured upgraded model embedded with three modules: VAR reactive‑power control, constant power‑factor regulation and process import‑export power control. The streamlined DSLC lacks these functions and only supports synchronizing‑paralleling and active load sharing, suitable merely for simple single‑unit parallel applications.
Q2: Can WOODWARD 9905‑373 operate without the MSLC master controller?A2: MSLC is not required for multi‑unit island‑bus parallel operation. Multiple WOODWARD 9905‑373 units can achieve autonomous load sharing via the LON bus. MSLC master controller is mandatory only when the system needs to manage total import‑export power between the whole plant and utility grid.
Q3: Which voltage‑transformer wiring is compatible with WOODWARD 9905‑373?A3: The WOODWARD 9905‑373 adopts dedicated 120Vac open‑delta PT configuration. It cannot directly replace DSLC models with wye‑connected PT. Secondary PT terminal wiring inside cabinet shall be modified during replacement.
Q4: Is the 9907‑205 hand‑held programmer mandatory for commissioning WOODWARD 9905‑373?A4: All parameter configuration, status monitoring and fault retrieval can only be completed through the 9907‑205 hand‑held programmer. There is no direct PC software debugging channel, so it is an essential accessory for WOODWARD 9905‑373.
Q5: What are the wiring requirements for LON‑bus networking of multiple WOODWARD 9905‑373 units?A5: Use Woodward‑specified dedicated LON cable. Terminating resistors must be installed at both ends of the main bus. The maximum length of branch cables shall not exceed 600 mm. The upper limit of total bus nodes is 20 units. Shield grounding shall be implemented throughout wiring to suppress interference.
Q6: What causes reverse‑power tripping during grid‑paralleling of WOODWARD 9905‑373?
A6: Firstly check slip‑frequency synchronization parameters, ramp rate and speed‑bias output range. Secondly verify whether LON‑bus disconnection results in failed load sharing. Thirdly confirm reversed CT current‑transformer polarity. The issue can be resolved by adjusting load‑control parameters under Menu 2 of WOODWARD 9905‑373.
Recommended Part Numbers of the Same Brand
9905‑354 DSLC Digital Synchronizing & Load Controller (Streamlined, 120/240 Wye, 0.5‑4.5Vdc)9905‑355 DSLC Digital Synchronizing & Load Controller (Full‑featured, 120/240 Wye, 0.5‑4.5Vdc)9905‑363 DSLC Digital Synchronizing & Load Controller (Full‑featured, 240 Open‑delta, +3.0Vdc)9905‑366 DSLC Digital Synchronizing & Load Controller (Streamlined, 120 Open‑delta, 0.5‑4.5Vdc)9905‑369 DSLC Digital Synchronizing & Load Controller (Full‑featured, 240 Open‑delta, 0.5‑4.5Vdc)9905‑372 DSLC Digital Synchronizing & Load Controller (Streamlined, 120 Open‑delta, 500Hz PWM)9905‑373 DSLC Digital Synchronizing & Load Controller (Full‑featured, 120 Open‑delta, 500Hz PWM)9905‑374 DSLC Digital Synchronizing & Load Controller (Streamlined, 240 Open‑delta, 500Hz PWM)9905‑603 DSLC Digital Synchronizing & Load Controller (Full‑featured, 120/240 Wye, 1‑5Vdc)9905‑708 DSLC Digital Synchronizing & Load Controller (Full‑featured, 120 Open‑delta, 1‑5Vdc)9905‑710 DSLC Digital Synchronizing & Load Controller (Full‑featured, 240 Open‑delta, 1‑5Vdc)9907‑007 DSLC Digital Synchronizing & Load Controller (Streamlined, 120/240 Wye, +3.0Vdc)9907‑205 DSLC / MSLC Hand‑held Programmer8239‑082 LSIM Load‑Share Interface Module
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