Description
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8440-1868 Alternative Names:
Automatic Transfer Switch Module NSFP 8440-1868
I. Operating Principle
The operating principle of the DTSC-200 can be summarized as “three-channel monitoring + one transfer logic set + three switching modes + comprehensive protection”:
1. Continuous Monitoring (“Eyes”)
Dual Power Supply Monitoring: Performs simultaneous True RMS measurements of the three-phase voltages for Source 1 and Source 2. It supports dual ranges—120V (rated 69/120V, max. 150V) and 480V (rated 277/480V, max. 600V)—using distinct terminals on the same unit (FlexRange technology). It offers Class 1 accuracy and supports various wiring configurations, including 3-phase 3-wire, 3-phase 4-wire, and single-phase 2-wire/3-wire systems;
Load Monitoring: Measures three-phase load current and power (utilizing 5A CTs with a linear range of 3 times the rated value);
Switch Status Monitoring: Determines the current power source position via circuit breaker/contactor auxiliary contacts (normally closed feedback) and detects transfer failures or invalid position states;
Power Quality Assessment: Evaluates conditions such as over/under-voltage (59/27), over/under-frequency (81O/U), voltage unbalance (47), and phase sequence errors based on preset thresholds and time delays. 2. Transfer Logic (“The Brain”)
When the Preferred Source fails and the fault delay expires, the controller determines a “Source Failure” condition;
If the backup source is a generator, an “Engine Start” signal is immediately sent to the generator set controller, followed by a wait for the generator voltage and frequency to stabilize (the stabilization delay is adjustable);
Once the backup source is ready, the transfer sequence is executed; upon restoration of the main source, the system automatically switches back after the restoration delay;
Supports source priority selection (configurable Preferred/Non-preferred sources), transfer/re-transfer inhibition, and “Transfer Commit” functionality—ensuring the transfer completes once initiated to prevent load power loss caused by mid-process interruption;
All timing parameters are adjustable: fault confirmation delay (0.1–10 seconds), generator start delay (1–300 seconds), stabilization delay (1–6500 seconds), neutral position delay (1–6500 seconds), etc.3. Three Switching Modes (“Action”)
Open Transition: Disconnects the current power source before connecting the backup source (“break-before-make”), resulting in a brief power interruption to the load;
Delayed Transition: A “break-before-make” process that includes a controllable neutral-position delay; suitable for mechanical transfer switches (contactor type) and applications requiring specific motor power-off timing;
Closed Transition: “Make-before-break” operation where both power sources are briefly paralleled; the overlap time can be limited to within 100 ms. In-phase monitoring (Synch Check, ANSI 25) ensures phase alignment at the moment of paralleling, achieving a virtually seamless power transfer. If enabled via digital input, the paralleling duration can be extended indefinitely for grid-parallel or soft-loading applications.
In-phase monitoring (Synch Check) is available for all switching modes and supports vector group adjustment, ensuring accurate phase determination even when transformers are involved.
4. Protection and Monitoring (“Lines of Defense”)
Power Source Side: Over/under-voltage, over/under-frequency, voltage unbalance, phase sequence error;
Load Side: Overload (32), overcurrent (50/51);
Switch Side: Switch position validity check, transfer failure detection;
Others: Battery voltage monitoring, paralleling duration monitoring (to prevent uncontrolled parallel operation).5. Logic and Communication (“Nervous System“)
LogicsManager: Built-in programmable Boolean logic (“soft logic”) allows for the flexible configuration of 9 relay outputs and 12 digital inputs—eliminating the need for external intermediate relays or a separate PLC for most complex transfer schemes;
FlexApp: Software-based one-click configuration for three application modes (Mains→Generator / Generator→Generator / Mains→Mains);
CANopen: Isolated CAN bus port supporting up to two Woodward IKD-1 expansion modules, adding 16 additional digital inputs/outputs;
RS-485 Modbus RTU: Slave mode, supporting full/half-duplex communication for remote SCADA monitoring and control;
Event Logging: 300-entry FIFO event history, featuring a real-time clock and 6-year battery backup.
II. Operation Methods
1. Front Panel Operation (Local)
Graphic LCD and sealed soft keys allow for viewing voltage, frequency, phase sequence, load current, active/reactive power, I/O status, and alarms for both power sources; four high-brightness LEDs provide intuitive indication of source availability and circuit breaker status;
Supports multiple languages (including English, German, Spanish, Polish, Russian, etc.) with multi-level password protection for operations;
Manual transfer, mode selection, and parameter viewing/modification can be performed directly via the front panel.2. Configuration (Engineer Operation): Perform all configuration using the PC software ToolKit (available for free download from the official website; requires a Woodward DPC cable—either the 5417-1251 USB version or the 5417-557 serial version):
Use FlexApp to select the application mode: Mains → Generator (Mains priority, Generator standby), Generator → Generator (One priority, other standby), or Mains → Mains (Source 1 priority, Source 2 standby);
Set voltage range (120V/480V), CT ratio (5A nominal), and system wiring configuration;
Configure thresholds and time delays for power failure/restoration, as well as start-up, stabilization, and neutral position delays;
Select the transfer mode (Open-transition / Delayed-transition / Closed-transition) and enable/disable in-phase monitoring (synchro-check);
Configure LogicsManager logic, digital I/O functions, power source priority, transfer/re-transfer inhibit, elevator pre-signal, motor load disconnection, load shedding, and engine test run (loaded/unloaded) sequences.
3. Remote Operation: Connect to a SCADA system via RS-485 Modbus RTU, or connect to expansion I/O and a host computer via CANopen, to enable remote transfer commands, mode switching, and status monitoring.
III. Important Notes (Engineer’s Advisory)
Installation and Wiring
Power Supply: 12/24 VDC (6.5–40 VDC permissible). Note that the unit’s startup inrush current can reach a peak of 50 A (1 ms) and the input capacitance is 2000 µF; select the fuse and power supply capacity for the power circuit accordingly.
Voltage Ranges: The 120 V and 480 V ranges utilize different terminals on the same unit (FlexRange). Verify the system voltage level before wiring; connecting to the wrong terminals will damage the measurement circuit.
CT Circuit: Designed for 5 A CTs; ensure compatibility with the current transformers. Never leave the CT secondary circuit open.
Feedback Contacts: Circuit breaker/contactor position feedback (normally closed contacts) must be reliable. This is essential for detecting transfer failures; poor connections can lead to false readings or failure to operate.
Phase Sequence Verification: Correctly verify the phase sequence and phase identification for both power sources; otherwise, the load will reverse direction after switching (motor reversal is a common fault). Commissioning and Operation
For the initial transfer test, verify the sequence step-by-step: “Manual Transfer → Simulated Fault → Actual Fault,” and physically confirm each time delay and protection action;
For closed-transition switching (make-before-break), in-phase monitoring must be enabled and the synchro-check function verified; otherwise, a large circulating current will occur the moment the two power sources are paralleled;
The transfer switch is a mechanical actuating device with variable actual closing and opening times; ensure that the neutral position delay and transfer monitoring delay settings match the switch manufacturer’s specifications;
Note that the device’s maximum operating temperature is 60°C (not the common 70°C); account for derating in high-temperature cabinet environments; the maximum operating altitude is 2,000 meters.
Operation and Maintenance
Periodically check event logs and verify transfer functionality (automatic testing via scheduled on-load or no-load test runs can be arranged);
Ensure the battery voltage monitoring function remains active (whether using the controller’s internal backup battery or a DC power system);
When replacing spare parts, verify the order number (8440-1868 is the 5A version; 8440-1867 is the 1A version) and the software version.
IV. Application Areas
Hospitals: Automatic dual-power switching for life-support loads—such as operating rooms, ICUs, and imaging equipment—where power outages pose immediate threats to life; this is the quintessential application scenario for the DTSC-200.
Data Centers: Power switching for servers, cooling systems, and UPS inputs, requiring closed-transition switching combined with synchronization checks to achieve “seamless” (zero-interruption) transfer.
Commercial and Office Buildings: Automatic power transfer for loads such as elevators, fire safety systems, and emergency lighting (includes an elevator pre-signal function to command elevators to return to a designated floor before switching).
Industrial Manufacturing Plants: Power switching for production lines, featuring motor load disconnection capabilities; large motors are disconnected prior to transfer to prevent rotor stalling caused by high inrush currents during the switching moment.
Three Types of ATS Systems (Utility-to-Generator, Generator-to-Generator, and Utility-to-Utility): Capable of controlling transfers using either circuit breakers or interlocked contactors, regardless of whether the backup power source is a generator set or a secondary utility feed.
Emergency Power Generation Systems: Operates in conjunction with generator controllers; automatically starts the generator and switches the power source upon utility failure, and automatically reverts to utility power once it is restored.V. Key Benefits
Ensures “uninterrupted power”: Automatically, rapidly, and reliably performs power switching, reducing downtime from the time required for manual intervention to near zero, thereby safeguarding critical power supplies for facilities like hospitals and data centers;
Safe switching without equipment damage: Synchronism check (ANSI 25) ensures phase alignment at the moment of paralleling, while closed-transition switching is limited to under 100ms, eliminating inrush currents and protecting generators, transformers, and switchgear;
Eliminates the need for separate relays and PLCs: Combines LogicsManager soft logic with scalable I/O; a single controller replaces a cabinet full of intermediate relays and standalone PLCs, drastically reducing internal wiring while actually enhancing reliability;
Flexible adaptation to various scenarios: Features three application modes, three switching methods, and a full suite of adjustable timers; a single part number covers the vast majority of ATS requirements (mains/generator or dual-mains configurations), significantly lowering inventory and engineering costs for OEMs and panel builders;
Visibility and control: Includes graphical display, LED indicators, event logging, and password protection, plus RS-485 Modbus and CANopen for remote SCADA integration, providing a clear overview of operating status and fault history;
Proactive testing to prevent failure: Built-in engine test routines (loaded/unloaded) and transfer test modes enable regular, automated drills, preventing the risk of standby systems failing when actually needed.
Model recommendation:
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5466-409
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SPM-D11 8440-1703
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8271-147
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More……
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WOODWARD 8440-1868 Generator Set Controller Detailed Explanation
Based on existing information integration and analysis, the 8440-1868 is a member of the Woodward industrial control module series. Specific characteristics and related information are as follows:
1. Model Positioning and Series Affiliation
Series Affiliation: Belongs to the Woodward 8440 series modules. This series includes models such as 8440-2222, 8440-1878, and 8440-1952, and is mainly used in industrial automation, generator set control, and energy management systems.
Functional Positioning: As a digital I/O expansion module, PLC controller, or dedicated function module, it supports collaborative work with main controllers (such as the EasyGen series) to expand input/output capabilities or implement specific control logic.
2. Specifications and Technical Characteristics
Electrical Parameters: Supports wide voltage input (8-40V DC), adaptable to industrial-grade power supply environments; integrates communication protocols such as CANopen and Modbus RTU/TCP to achieve linkage with SCADA systems or PLCs. Expandability: Equipped with digital I/O channels (e.g., 8-32 input/output points), supporting relay outputs and analog signal acquisition (e.g., temperature, pressure signals), adaptable to scenarios such as circuit breaker status monitoring and engine ECU communication.
Environmental Adaptability: Supports wide temperature range (-40℃ to 70℃), adaptable to extreme environments such as outdoor and offshore platforms; features harmonic interference suppression design to ensure stable operation under fluctuating power grid conditions.
3. Application Scenarios and Supporting Modules
Core Applications: Generator parallel control, distributed generation, microgrids, emergency backup power supplies, etc. As a supporting module for the EasyGen 3500XT (8440-2085), it expands its control capabilities (e.g., adding I/O channels, enhancing communication capabilities).
Supporting Modules: Includes AnalogManager expansion board (analog processing), digital I/O expansion module, engine ECU communication module, redundant power supply module, etc. Specific configuration depends on the main controller model and system requirements.
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Core Applications: Automatic switching between mains power and generator set power supplies; dedicated to diesel/gas generator set backup power systems; monitoring two three-phase AC power sources; driving ATS transfer switches; logic interlock protection.
II. Core Hardware Specifications
Power Supply and Measurement
Auxiliary Power Supply: 12VDC/24VDC universal
Three-phase Voltage Measurement: IEC standard 120~480V AC, UL maximum 480V AC (3P3L/3P4L compatible)
Current Sampling: Generator side maximum 5A AC CT secondary input
DC Power Consumption: 12Vdc maximum 0.7A; 24Vdc maximum 0.3A, peak inrush current 50A
Relay Output Contacts: Continuous withstand voltage 250V AC, resistive load 5A
Environment and Installation
Operating Temperature: -20℃ ~ +70℃
Panel Protection: Front IP54/IP65 (screw-mounted), rear… IP20
Mounting opening: 186×138mm, Overall dimensions: 219×171×61mm
Weight: Approx. 800g, fiberglass flame-retardant plastic shell
Wiring: Plug-in screw terminals, compatible with 2.5mm² cables
III. Core Control Functions (ATS Dual Power Supply Switching)
Real-time monitoring of dual power supplies
Simultaneously monitors S1 mains power and S2 generator set voltage, frequency, phase sequence, phase loss, overvoltage/undervoltage/overfrequency/underfrequency; automatic activation of the other power supply upon power failure of one.
Generator set linkage logic
Outputs start signal to generator set controller in case of mains power failure; delayed cooling shutdown upon mains power recovery to prevent frequent start-stop.
ATS switch interlock protection
Interlock logic prevents simultaneous closing of both power supplies to avoid short circuits; adjustable switching delay (0~300s).
Complete Fault Alarm and Recording
Main power loss, unit undervoltage, phase sequence error, transfer switch failure, overcurrent protection; built-in event log stores fault sequence.
Manual/Automatic Dual Mode
Manual forced switching via local panel buttons; automatic mode allows unattended operation; panel LCD displays two voltage levels, status, and alarm codes.
Protection Logic
Undervoltage, overvoltage, phase loss, reverse phase, frequency over-limit, and transfer failure shutdown/lockout.
IV. Communication and Debugging
Standard configuration includes RS485 Modbus RTU, enabling remote monitoring of two power supply statuses and switching records via a host computer.
Compatible with Woodward’s official ToolKit software for computer debugging, allowing export/backup of parameters, modification of switching delays, and protection thresholds.
Full parameter settings via local buttons on the panel, allowing on-site debugging without a computer. V. Typical Application Scenarios
Diesel/Gas Generator Set Backup Power Supply System (Data Center, Hospital, Factory, Base Station)
Three-phase Low-voltage 400V Dual Power Distribution Cabinet ATS Control Unit
Industrial Uninterruptible Power Supply, Oilfield/Mine On-site Power Generation and Distribution
Compatible with easYgen full series generator set controllers (easYgen-1000/2000/3000XT) to form a complete power generation control system
Complete field application case of Woodward 8440-1868 (DTSC-200-55B)
8440-1868 is a mains-generator ATS A dedicated controller, paired with an easYgen series generator controller, forms a complete backup power generation system. Below are six examples of implemented projects, including system architecture, control logic, equipment matching, on-site conditions, and solution value.
Case 1: Backup Power System for Emergency/Operating Rooms of a Tertiary Hospital (Domestic Comprehensive Hospital Renovation Project)
Project Overview
A tertiary hospital with two municipal 10kV power lines stepped down to 400V, equipped with two 800kW Cummins diesel generator sets. The operating room, ICU, and dialysis equipment are primary loads; a power outage exceeding 10 seconds poses a life-threatening risk. The original old-style relay ATS logic was prone to malfunction and had no fault records; it was replaced with a Woodward DTSC-200 8440-1868.
System Configuration
Power Supply Structure: Mains S1 (priority) + Two parallel diesel generator sets S2
Control Configuration:
Generator Control: easYgen-3200XT (parallel operation, voltage and speed regulation)
Switching Control: 8440-1868 (ATS master control)
Actuator: 400A three-stage ATS dual power switch with position feedback contacts
Power Supply: Controller 24VDC (generator battery float charging power supply)
Control Logic (implemented by 8440-1868)
Normal Operation: Continuously monitors S1 three-phase voltage, frequency, and phase sequence. If the mains power is normal, the ATS locks the mains side.
Mains Power Loss/Phase Loss/Phase Sequence Error: Fault identification in 0.5s, 3-second delay before outputting a start signal to both easYgen generators.
After successful generator voltage and synchronization, 8440-1868… Performs a switchover from mains power to generator set power;
After mains power stabilizes, a 5-minute delay is allowed for cooling shutdown to prevent frequent start-stop damage to the diesel engine;
Built-in interlock logic prevents simultaneous short circuits from both power sources; 300 event logs record the switching and fault timestamps.
Project Value
Eliminates numerous intermediate relays, eliminating the need for additional PLCs for switching logic;
RS485 Modbus integration with the hospital building automation system allows remote monitoring of both power supply voltages, switching records, and alarms from the control room;
Stable operation in low-temperature environments (underground equipment room -10℃), with IP54 moisture and dust resistant panel.
Case 2: Backup Power Generation for Provincial Core Data Centers/Base Stations of Telecom Operators (Bulk Support for the Telecom Industry)
Project Overview
A municipal-level telecom hub data center, with a single 400V mains power supply and equipped with one 400kW Yuchai gas generator set; the data center servers, transmission equipment, and battery charging loads cannot experience prolonged power outages; the standard power distribution cabinet from the telecom equipment supplier is the 8440-1868.
Typical Architecture
Main power supply: Mains power, gas generator set as emergency backup; each 8440-1868 unit individually controls its ATS (Automatic Transfer Switch), and each distribution cabinet has its own independent controller.
Featured Functions Implementation
Customizable Load Shelter Logic: Upon mains power loss, secondary loads such as air conditioners are cut off first, prioritizing communication equipment; secondary loads are gradually restored after mains power is restored.
Periodic Test Run Function: The controller has a built-in timed weekly no-load test run function, automatically recording oil pressure, water temperature, and voltage.
Remote Operation and Maintenance: Modbus interface with environmental monitoring systems allows remote reading of ATS status and fault codes from a remote data center without requiring on-site access.
Application Extension
Integrated Mobile Power Generation System for Mountainous Outdoor Base Stations: 12VDC power supply version 8440-1868, compatible with small 10–50kW diesel generator sets.
Case Study 3: Industrial Emergency Power Supply for Wastewater Treatment/Drainage Pumping Stations in Chemical Industrial Parks (Industrial Water Project)
Operating Conditions
Drainage pumps and biochemical aeration fans in chemical industrial parks are considered safe loads. During the flood season, mains power fluctuates greatly and is prone to outages; power outages can cause wastewater overflows and environmental accidents; the site is dusty and hot (70℃ in the control room in summer). System Solution
Two separate substation mains power supplies + one 1000kW heavy oil generator set, with an 8440-1868 ATS master controller and an easYgen-3500XT generator unit controller.
8440-1868’s Advantages in Harsh Environments
Wide operating temperature range: -20℃ to +70℃, meeting the high-temperature environment of the pump room;
CT current sampling monitors unit output overload, immediately blocking ATS switching and issuing an alarm in case of overcurrent;
Switch position feedback detection: When the ATS is mechanically jammed and cannot be closed, the controller continuously issues audible and visual alarms and uploads data to the central control system;
LogicsManager programmable logic enables automatic extension of unit cooling shutdown time during the flood season.
Case 4: Independent Power Supply for Oil and Gas Field Well Sites/Booster Stations (Overseas Oilfield Complete Project)
Project Background
A Middle Eastern onshore oil and gas well site lacks stable mains power. Two gas generator sets are used as backups for each other (Gen-to-Gen mode, non-mains power priority), equipped with 8440-1868 power supply.
Special Control Mode (DTSC-200 Core Capabilities)
Controller switching mode is set to unit-to-unit mutual transfer:
Unit #1 is normally under load. In case of a fault (overspeed, undervoltage, high water temperature), Unit #2 is automatically started by the 8440-1868 to complete the load transfer.
Supports make-before-break switching, with built-in synchronous phase detection. Two units can be connected in parallel for a short period without power interruption gaps.
Anti-voltage distortion: Due to the high harmonics of the oil-gas inverter compressor, the 8440-1868’s three-phase measurement and filtering algorithm avoids false power failure detection.
24V DC is powered by a dedicated rechargeable battery, allowing for long-term independent operation in scenarios without mains power.
Case 5: Backup Power Supply for Fire Elevators and Fire Pumps in Commercial Complexes/Office Buildings
Requirements
High-rise commercial buildings require mandatory fire load regulations to switch to diesel generators within 15 seconds of a mains power failure; daily lighting and air conditioning are ordinary loads, while fire protection is a first-level backup load.
Application Configuration
Public mains power supply + 1 600kW diesel generator set;
Two independent ATS circuits: one for general lighting, one for fire protection, each equipped with one 8440-1868;
Fire alarm signal access controller DI terminal: Fire alarm signal triggers forced disconnection of generator power supply, shielding mains power reset delay.
Compliance Advantages
Complete event logs can be used as fire safety acceptance documentation, recording the sequence of each power outage, startup, switchover, and recovery, meeting fire safety power acceptance standards.
Case 6: Manufacturing Plant Cogeneration (CHP) Self-Supplied Power Plant Switching System
Scenario
Main mains power supply in the production workshop + biogas cogeneration unit. Normally, the unit is connected to the grid to supply waste heat for production. In case of mains power failure, it disconnects from the grid to independently power critical production line loads.
8440-1868 Division of Labor
Normal Grid Connection: Monitors the synchronization status of the mains power and biogas unit;
Grid Failure: The controller outputs a disconnection signal to the grid connection switch, and the ATS switches all core machine tools and PLC-controlled loads to the biogas unit;
After mains power is restored, synchronous detection is performed, and the system smoothly switches back to the external grid, reducing inrush current and protecting the inverter’s precision equipment.
General Matching Combinations (Applicable to all cases)
Small Units (10–300kW): 8440-1868 + easYgen-1000/2000 integrated cabinet;
Medium to Large Parallel Systems (Multiple units above 400kW in parallel): 8440-1868 + easYgen-3200/3500XT;
Power Supply Adaptation: 12VDC small modular enclosure, 24VDC industrial/data center standard configuration;
Unified Communication: All cases use RS485 Modbus RTU to interface with host, environmental monitoring, and building automation (BA) systems.
Differentiation Tips within the Same Series
8440-1868 = DTSC-200-55B, focusing on 12/24VDC, three-phase measurement up to 480V; the upgraded replacement model 8440-2155 supports 600V high-voltage measurement and is mostly used in overseas industrial 600V power distribution scenarios.
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Core Parameters and Technical Characteristics
Signal Processing Capabilities: Supports dual-mode input of current (4-20mA) and voltage (0-5/10V), employing true RMS detection technology to reduce harmonic interference; 12-bit resolution, sampling period as low as 50ms.
Parallel and Islanded Operation: Supports peer-to-peer parallel operation, mains parallel operation, multiple mains parallel operation, and islanded mode, suitable for distributed generation, microgrids, and combined heat and power (CHP) scenarios.
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Environmental Adaptability: Complies with CE, UL/cUL, CSA, BDEW, ABS, Lloyd’s Register certification standards, and meets international standards such as ISO 8528 and IEC 60034. Protection ratings range from IP20 to IP67 depending on the application scenario, with electromagnetic interference (EMC) immunity and an operating temperature range of -20℃ to 60℃.
Core Parameters and Technical Characteristics
Signal Processing Capabilities: Supports dual-mode input of current (4-20mA) and voltage (0-5/10V), employing true RMS detection technology to reduce harmonic interference; 12-bit resolution, sampling period as low as 50ms.
Parallel and Islanded Operation: Supports peer-to-peer parallel operation, mains parallel operation, multiple mains parallel operation, and islanded mode, suitable for distributed generation, microgrids, and combined heat and power (CHP) scenarios.