Usage:
Scope
This chapter contains general installation instructions for the 705 control. Power requirements, environmental precautions, and location considerations are included to help you determine the best location for the control. Additional information includes unpacking instructions, electrical connections, and installation checkout procedures.
Unpacking
Before handling the control, read Chapter 3, Electrostatic Discharge Awareness. Be careful when unpacking the electronic control. Check the control for signs of damage such as bent panels, scratches, and loose or broken parts. If any damage is found, immediately notify the shipper.
Power Requirements
The low-voltage 705 control requires a low-impedance voltage source of 20 to 40 Vdc at 8 watts. Apply and remove power to the control only through a non-bouncing switch.
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To prevent damage to the control, do not exceed the input voltage range. |
NOTE: If a battery is used for operating power, an alternator or other battery-charging device is necessary to maintain a stable supply voltage.
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To prevent damage to the control, make sure that the alternator or other battery-charging device is turned off or disconnected before disconnecting the battery from the control. |
Location Considerations
Consider these requirements when selecting the mounting location:
- * adequate ventilation for cooling;
- * space for servicing and repair;
- * protection from direct exposure to water or to a condensation-prone environment;
- * protection from high-voltage or high-current devices, or devices which produce electromagnetic interference;
- * avoidance of vibration;
- * selection of a location that will provide an operating temperature range of -40°C (-40°F) to +70°C (+158°F).
- * space for servicing and repair;
The control must NOT be mounted on the engine.
Electrical Connections
External wiring connections and shielding requirements for a typical control installation are shown in the plant wiring diagram, Figure 4-1. The plant wiring connections are explained in the rest of this chapter.
Shielded Wiring
All shielded cable must be twisted conductor pairs. Do not attempt to tin the braided shield. All signal lines should be shielded to prevent picking up stray signals from adjacent equipment. Connect the shields to the nearest chassis ground. Wire exposed beyond the shield should be as short as possible, not exceeding 50 mm (2 inches). The other end of the shields must be left open and insulated from any other conductor. DO NOT run shielded signal wires along with other wires carrying large currents. See Woodward application note 50532, Interference Control in Electronic Governing Systems for more information.
Where shielded cable is required, cut the cable to the desired length and prepare the cable as instructed below.
1. Strip outer insulation from BOTH ENDS, exposing the braided or spiral wrapped shield. DO NOT CUT THE SHIELD.
2. Using a sharp, pointed tool, carefully spread the strands of the shield.
3. Pull inner conductor(s) out of the shield. If the shield is the braided type, twist it to prevent fraying.
4. Remove 6 mm (1/4 inch) of insulation from the inner conductors.
Installations with severe electromagnetic interference (EMI) may require additional shielding precautions. Contact Woodward Governor Company for more information.
Power Supply
Power supply output must be low impedance (for example, directly from batteries). DO NOT power low-voltage versions of the control from high-voltage sources with resistors and zener diodes in series with the control power input. The 705 control contains a switching power supply which requires a current surge to start properly.
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To prevent damage to the control, do not power the low-voltage control from high-voltage sources. |
Run the power leads directly from the power source to the control. DO NOT POWER OTHER DEVICES WITH LEADS COMMON TO THE CONTROL. Avoid long wire lengths. Connect the positive to terminal 1 and negative to terminal 2. If the power source is a battery, be sure the system includes an alternator or other battery-charging device.
If possible, do NOT turn off control power as part of a normal shutdown procedure. Use the Minimum Fuel discrete input (terminal 9) for normal shutdown. Leave the control powered except for service of the system and extended periods of disuse.
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Do NOT apply power to the control at this time. Applying power may damage the control. |
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To prevent damage to the engine, apply power to the 705 control at least ten seconds prior to starting the engine. The control must have time to perform its power up diagnostics and become operational. Do not start the engine if the diagnostic tests fail, because test failure turns off the output of the control. |
Actuator Output
The actuator wires connect to terminals 3(+) and 4(-). Use shielded wires with the shield connected to chassis at the control.
Aux Output
The tachometer or actuator position readout wires connect to terminals 5(+) and 6(-). Use shielded twisted-pair wires. For an electrically isolated input device such as a 4 to 20 mA input analog meter, the shield should be grounded at the control end of the cable. For input to other devices, use the recommendation of the device manufacturer.
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To prevent possible damage to the control or poor control performance resulting from ground loop problems, follow these instructions. The control common is electrically isolated from the power supply input; however, the actuator and Aux outputs are current sources and have a common mode voltage on them with respect to the control's internal common (terminal 7 - Aux Common). The analog inputs to the control use this same common. Connecting the actuator or Aux outputs to external circuits that are not isolated from the remote speed setting 4 to 20 mA current source will create ground loop problems. We recommend using current-loop isolators if the 705 control's analog inputs and outputs must both be used with non-isolated devices. A number of manufacturers offer 20 mA loop isolators. Consult Woodward Governor Company for further information. |
Discrete Inputs
Discrete inputs are the switch input commands to the 705 control. Connect the discrete input voltage source negative (-) to terminal 8. Then run the voltage source positive (+) to the appropriate switch or relay contact and then to the corresponding discrete input.
Minimum Fuel Contact
The minimum-fuel contact is the preferred means for a normal shutdown of the engine. It connects to terminal 9, Discrete Input A, of the control. The control will not operate without voltage applied to terminal 9. When the contact is closed, the voltage applied to terminal 9 allows the control to move the actuator to any position required for operating conditions.
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The minimum-fuel contact is not intended for use in any emergency stop sequence. To prevent possible serious injury from an overspeeding engine, do NOT use the minimum-fuel contact as part of any emergency stop sequence. |
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Idle/Rated Contact
If used, the Idle/Rated contact (open for Idle, closed for Rated) connects to terminal 10, Discrete Input B. This contact also determines which fuel limiter is in effect. In Idle, the control uses the Start Fuel Limit set point. In Rated, the control uses the Torque Limit and Turbo Boost Pressure Limit set points. When the Idle/Rated contact is closed, the control immediately switches the fuel limit to the Turbo Boost Pressure Limit and ramps engine speed to the rated speed set point (or the speed specified by the Remote Input when the Remote Speed Setting input is enabled). When the Idle/Rated contact is opened, the control immediately switches on the Start Fuel Limit and ramps engine speed to the idle speed setting.
The idle set point cannot be set above the rated set point. The fuel limiters (start, boost, and torque) remain effective regardless of the Local/Remote input.
Lower Speed Contact
If used, the Lower Speed contact connects to terminal 11, Discrete Input C. When the Lower Speed contact is closed, the control lowers speed at a rate determined by the Lower Rate set points. When the contact is open, speed remains at its current value. Actuating the Lower Speed contact will cancel the ramps started by the Idle/Rated contact.
The Lower Speed contact input is disabled when the Remote Speed Setting mode is selected by closing both the Lower Speed and Raise Speed contacts.
Raise Speed Contact
If used, the Raise Speed contact connects to terminal 12, Discrete Input D. When the Raise Speed contact is closed, the control raises speed at a rate determined by the Raise Rate set points. When the contact is open, speed remains at its current value. Actuating the Raise Speed contact will cancel the ramps started by the Idle/Rated contact.
The Raise Speed contact input is disabled when the Remote Speed Setting mode is selected by closing both the Lower Speed and Raise Speed contacts.
Alternate Dynamics
If used, the Alternate Dynamics contact connects to terminal 13, Discrete Input E. When this contact is open, Dynamics set 1 is selected. When this contact is closed, Dynamics set 2 is selected.
Raise/Lower Rate 3
If used, the Raise/Lower Rate 3 contact connects to terminal 14, Discrete Input F. When the contact is open, the speed reference changes at the Raise Rate 1/Lower Rate 1 or Raise Rate 2/Lower Rate 2 (depending on which side of the Rate break point the reference is) when the remote reference is changed or the Raise or Lower contacts are closed.
When the Raise/Lower Rate 3 contact is closed, the speed reference is only allowed to change at the Raise Rate 3/Lower Rate 3 set points. This will normally be used when a fast rate is desired, such as for maneuvering in a marine propulsion application, when direct control of the speed reference is needed.
Speed Signal Input
Connect a speed-sensing device, such as a magnetic pickup, to terminals 15 and 16 using shielded wire. Connect the shield to the chassis. Make sure the shield has continuity the entire distance to the speed sensor, and make sure the shield is insulated from all other conducting surfaces.
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The number of gear teeth is used by the control to convert pulses from the speed sensing device to engine rpm. To prevent possible serious injury from an overspeeding engine, make sure the control is properly programmed to convert the gear-tooth count into engine rpm. Improper conversion could cause engine overspeed. |
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Remote Speed Setting Input
If used, connect the 4 to 20 mA current transmitter or 1 to 5 Vdc voltage transmitter to terminals 18(+) and 19(-). Use a shielded, twisted-pair cable. When using a 4 to 20 mA transmitter, you must install a jumper between terminals 17 and 18 to connect a 243 ohm internal burden resistor in the loop. This input is not isolated from the other control inputs and outputs (except the power supply input and the discrete inputs). If any other analog input or output is used in a common ground system, an isolator must be installed. A number of manufacturers offer 20 mA loop isolators. Consult Woodward Governor Company for further information.
Rack Limiter Input
If used, connect the 4 to 20 mA current transmitter of the turbo boost pressure sensor to terminals 21(+) and 22(-). Use a shielded, twisted-pair cable. When using a 4 to 20 mA transmitter, you must install a jumper between terminals 20 and 21 to connect the 243 ohm internal burden resistor in the loop. This input is not isolated from the other control inputs and outputs (except the power supply input and the discrete inputs). If any other analog input or output is used in a common-ground system, a loop isolator must be installed. A number of manufacturers offer 20 mA loop isolators. Contact Woodward Governor Company for further information.
Installation Checkout Procedure
With the installation complete as described in this chapter, perform the following checkout procedure before beginning the start-up adjustments in Chapter 5.
1. Visual inspection
A. Check the linkage between the actuator and fuel metering device for looseness or binding. Refer to the appropriate actuator manual, and Manual 25070, Electric Governor Installation Guide for additional information on linkage.
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To prevent possible serious injury from an overspeeding engine, the actuator lever or stroke should be near but not at the minimum position when the fuel valve or fuel rack is at the minimum fuel delivery position. |
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B. Check for correct wiring in accordance with the Plant Wiring Diagram, Figure 4-1.
C. Check for broken terminals and loose terminal screws.
D. Check the speed sensor for visible damage. If the sensor is a magnetic pickup, check the clearance between the gear and the sensor, and adjust if necessary. Clearance should be between 0.25 and 1.25 mm (0.010 and 0.050 inch) at the closest point. Make sure the gear runout does not exceed the pickup gap.
2. Check for grounds
Check for grounds by measuring the resistance from all control terminals to chassis. All terminals except terminals 2 and 8 should measure infinite resistance (the resistance of terminals 2 and 8 depends on whether a floating or grounded power source is used). If a resistance less than infinite is obtained, remove the connections from each terminal one at a time until the resistance is infinite. Check the line that was removed last to locate the fault.
3. Once the control is powered up and the Set Point Programmer is plugged in, all the input wiring can be verified by observing each input on the display menu (D), and varying the input (opening and closing discrete contacts, or varying the analog inputs, etc.). On this menu only, the up or down arrows can be used to continuously update the display.
Figure 4-1. Plant Wiring Diagram