20801971 Volvo.Penta Gear

Unpacking
Before handling the control, read Chapter 2, 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 high-voltage versions of the 721 Digital Speed Control require a voltage source of 88 to 132 Vac 45 to 65 Hz or 90 to 150 Vdc. The low-voltage versions require a voltage source of 18 to 40 Vdc.
To prevent damage to the control, do not exceed the input voltage range.
If a battery is used for operating power, an alternator or other battery-charging device is necessary to maintain a stable supply voltage.
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
* 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 to +70 °C (-40 to +158 °F).The control must NOT be mounted on the engine.Internal Jumpers
The 721 control has nine, two-position internal jumpers (JPR1 through JPR18) located on the top of the printed circuit board. If you need to change any jumper to match your control needs, be sure to read Chapter 2, Electrostatic Discharge Awareness, before proceeding.With the power off, remove the control cover. With your fingers or a small pair of tweezers, carefully remove the appropriate jumper and replace it securely over the proper two connectors (see Figure 3-1).The jumper connections are listed here. Factory settings are shown with an "*". JPR1 analog output #1 0-1 mA* JPR2 analog output #1 0-20 mAJPR3 analog output #2 0-1 mA* JPR4 analog output #2 0-20 mAJPR5 analog output #3 0-1 mA* JPR6 analog output #3 0-20 mA* JPR8 and JPR9 actuator output 0-200 mA, singleJPR8 and JPR10 actuator output 0-20 mA, singleJPR7 and JPR9 actuator output 0-200 mA, tandemJPR11 and JPR15 speed sensor #1 proximity switch* JPR12 and JPR16 speed sensor #1 magnetic pickupJPR13 and JPR17 speed sensor #2 proximity switch* JPR14 and JPR18 speed sensor #2 magnetic pickup
Figure 3-1. 721 Control Internal JumpersElectrical Connections
External wiring connections and shielding requirements for a typical control installation are shown in Figures 1-6 and 1-7. 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 (Terminals 1/2)
Power supply output must be low impedance (for example, directly from batteries). DO NOT power the control from high-voltage sources with resistors and zener diodes in series with the control power input. The 721 control contains a switching power supply which requires a current surge to start properly.
To prevent damage to the control, do not power a low-voltage control from high-voltage sources, and do not power any control from high-voltage sources with resistors and zener diodes in series with the power input.
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 (line) to terminal 1 and negative (common) 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 (Run/Stop) discrete input (terminal 25) for normal shutdown. Leave the control powered except for service of the system and extended periods of disuse.
Do NOT apply power to the control at this time. Applying power may damage the control.
To prevent damage to the engine, apply power to the 721 control at least ten seconds prior to starting the engine. The control must have time to do its power up diagnostics and become operational. Do not start the engine unless the green POWER AND CPU OK indicator on the 721 control cover comes on, because test failure turns off the output of the control.
Relay Outputs (Terminals 3/4, 5/6, 7/8) - (See page 8 (plant wiring notes) for contact ratings.)
Connect the Circuit Breaker Open relay, if used, to terminals 7/8 (normally closed). The contacts open momentarily to open the generator breaker.Connect the Major Alarm relay, if used, to terminals 5/6 (normally open). The contacts close to energize the relay (major alarm condition).Connect the Minor Alarm relay, if used, to terminal 3/4 (normally open). The contacts close to energize the relay (minor alarm condition).Load Signal Output (Analog Output #1; Terminals 9/10)
The Load Signal readout wires connect to terminals 9(+) and 10(-). 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.