2301D Load Sharing and Speed Control

    Digital load sharing and speed control for electric generator systems 

     2301D Digital Control  2301 Redesigned Sign 

    Woodward’s 2301D speed controls are used in electric generator systems where load sharing is desired. They are used with diesel or gas engines, or steam or gas turbines, and are compatible with all Woodward electronic controls. The microprocessor-based digital control is housed in a sheet-metal chassis and consists of a single printed circuit board. The flexible configuration software incorporated in the control hardware allows easy changes to accommodate engine speed range, gear teeth, and selection of forward or reverse acting.

    The increased flexibility of software allows the 2301D to include control functions that required additional equipment in previous versions of 2301A control systems. The 2301D therefore is suitable for upgrading existing control systems or increased functionality in new installations.

    The 2301D-EC is capable of communicating using a Modbus® RTU protocol, functioning as a Modbus slave device, via RS-232 or RS-422 drivers.


    The 2301D and 2301D-EC have four operating modes:


     Speed Control 

    •  Multiple dynamics flexibility
    •  Will work on pumps or compressors
    •  Capability for remote 4–20 mA speed reference through a configurable analog input

     Isochronous Load Sharing 

    •  Compatible with most existing load sharing speed control systems
    •  Soft load and unload capability

     Droop Base Load 

    •  Adjustable load control using discrete raise and lower contacts

     Isochronous Base Load 

    •  Provides constant load level operation against a bus
    •  Load setting may be fixed, changed using discrete raise and lower inputs, or a remote 4–20 mA input

    ® Modbus is a trademark of Schneider Automation Inc.



    •  Multiple dynamics
    •  Manifold Air Pressure (MAP) limiter
    •  Torque limiter
    •  Low speed sensing functionality
    •  Remote speed & load reference
    •  Soft load transfer
    •  Automatic idle to rated switching
    •  Load rejection / Load pulse option
    •  Idle droop function
    •  PC configurable
    •  Optional Modbus® serial communications
    •  Adaptive speed sensing algorithm

    Woodward Part Numbers:
                                      8273-101       2301D Load Sharing and Speed Control, 24 Vdc input, Ordinary Locations
                                      8273-135       2301D Load Sharing and Speed Control, 24 Vdc input, Hazardous Locations

                                      8923-932       Watch Window Installation

                     Power Supply Rating      18–40 Vdc (SELV)
                      Power Consumption       less than or equal 20 W nominal


                     Input Supply Voltage       Input Supply Current
                                               18 V      589 mA
                               24 V (nominal)      431 mA
                                               32 V      319.6 mA

                                Inrush Current      7 A for 0.1 ms (low-voltage model)
                                Inrush Current      22 A for 15 ms (high-voltage model)

              Steady State Speed Band      ± 0.25% of rated speed
                             Magnetic Pickup      100–25 000 Hz (300–3600 rpm)
                          Discrete Inputs (8)      3 mA at 24 Vdc, impedance approximately 5.2 k
                Remote Reference Input       0–20 mA, 4–20 mA, 0–5 Vdc, 1–5 Vdc, or ± 2.5 Vdc externally powered
                                   SPM-A Input       ± 2.5 Vdc, externally powered
                           Analog Output #1       0–20 mA, 4–20 or 0–200 mA to actuator, software configurable
                           Analog Output #2       0–20 or 4–20 mA to tachometer, internally powered
                       Discrete Outputs (4)       Configured to provide two speed switches & two load switches, power by external

                                                              +12 Vdc or +24 Vdc source, max output current 200 mA

                 Discrete Output Ratings       Low-side drivers with overvoltage protection, 200 mA maximum
                 Communication Port (J2)      RS-232, RS-422, 9-pin connector, 1200 to 38 400 baud, full duplex
     Ambient Operating Temperature      –40 to +70 °C (–40 to +158 °F)
                      Storage Temperature      –40 to +105 °C (–40 to +221 °F)
                                           Humidity      Lloyd’s Register of Shipping, Test Specification No. 1, 1996, Humidity Test 1, 95% at +20

                                                               to +55 °C (+68 to +131 °F) condensing
                       Mechanical Vibration      Lloyd’s Register of Shipping, Test Specification No. 1, Vibration Test 2 (5–25 Hz, ± 1.6 mm, 25–100 Hz, ± 4.0 g)
                           Mechanical Shock      US MIL-STD 810C, Method 516.2, Procedure I (basic design test), Procedure II (transit drop test, packaged), Procedure V (bench handling)
                  Equipment Classification     Class 1 (grounded equipment)

    Frequently Asked Questions about the 2301D Digital Load Sharing and Speed Control 


    Please see manual 26065 for comprehensive details on any of the topics below.


    Q1—What size wire can be used on the terminals? 


    A1—The spring clamp can be actuated by using a standard 2.5 mm or 3/32 inch flat bladed screwdriver. The terminal blocks accept wires from 0.08-4 mm² (27-12 AWG). Two 18 AWG or three 20 AWG wires can be easily installed in each terminal. Wires for the fixed mounted power terminals should be stripped 5-6 mm (1/4 inch) long.

    NOTE: Do not tin (solder) the wires that terminate at the terminal blocks. The spring-loaded terminal blocks are designed to flatten stranded wire and if those strands are tinned together the connection loses surface area and is degraded.





    Q2—How do I connect discrete inputs and what are they commonly used for? 


    A2—Discrete Inputs (Terminals 28-38) are the switch input commands to the 2301D control. They interact in such a way as to allow engine control and power management under a variety of conditions. Positive voltage is supplied to the discrete input terminal when an input switch or relay contact closes. Terminal 30 is the common input power and is negative in respect to the discrete inputs. This input must be connected to the negative source in order for the inputs to function.


    Q3—What type of communication is used on the 2301D, and what type of cable is used? 


    A3—There are two programs that are used with the 2301D: ServLink and Watch Window. Both programs must be opened to communicate with the 2301D. These programs may be downloaded from the Woodward website.


    The type of cable is RS-232 null modem. The drawing below shows the required connections in the null modem cable. These are the minimum connections. Some null modem cables have more interconnects that are not used by the 2301D control.




    Q4—What speed range can I use the 2301D on, and can I use it on a turbine application? 


    A4—See the chart below for speed ranges applicable to the 2301D. This control is not recommended for turbine applications.


    60 Hz

    50 Hz


    3600 rpm

    3000 rpm


    1800 rpm

    1500 rpm


    1200 rpm

    1000 rpm


    900 rpm


    NOTE: The maximum input frequency that can be measured by the speed sensing circuit is 25 000 Hz. Therefore to allow for transient conditions, the Number of Teeth times Rated RPM divided by 60 should be less than 19 000.


    Q5—I have a 4-20 mA remote speed set point but my speed is not changing. 


    A5—The following discrete inputs must be closed to enable the remote speed set point:

    • Terminals "A" 31
    • Terminals "C" 33
    • Terminals "E" 35
    • Terminals "E" 36

    Terminals 35 and 36 are the raise and lower discrete contacts. They must be closed to enable this mode. Maintained simultaneous closure of this Lower Speed/Load contact along with the Raise Speed/Load contact enables the Remote Reference Input.



    Q6—After my breaker closes, the unit will not load up. 



    A6—No input on terminal 37 load generator. If the state of the input is "FALSE" (input switch or relay contact open), the Load Control Function will increase or decrease in order to achieve the Unload Trip level. The CB Aux/Droop Contact discrete input must be "TRUE" for the Load Generator input.


    Q7—In the dynamic menu item 15 ( speed filter), how do I set it and what does it do? 



    A7—This is used for low speed engine application and was carried over from another application. Leave this value at default.



    Q8—My units don't load share equally. 


    A8—When paralleled in isochronous mode or on an isolated bus, generator speeds must be the same. If they are not equal, load sharing will not remain proportional as the load varies. Any difference in loads between the units can be corrected by adjusting the Load Gain.

    Procedure for this is in manual 26065.



    Q9—I have two current transformers (CTs). Do I have to add a third? 


    A9—No. See diagram below for optional current transformer connection.




    Q10—My old unit had my shields connected to the ground screw. Should I connect them as shown in the manual? 


    A10—YES! An individual shield termination is provided at the terminal block for each of the signals requiring shielding. All of these inputs should be wired using shielded, twisted-pair wiring. The exposed wire length beyond the shield should be limited to 25 mm (1 inch). Relay outputs, contact inputs, and power supply wiring do not normally require shielding, but can be shielded if desired.