GeneralThis section will familiarize the reader with the variouscomponents that make up the DC control system.Major DC control system components that will becovered include the following:• A Terminal Strip / Interconnection Terminal• A Circuit Board.• An AUTO-OFF-MANUAL Switch.• A 7.5 Amp Fuse.terminal Strip / interconnectionterminalThe terminals of this terminal strip are connected toidentically numbered terminals on a transfer switchterminal board. The terminal board connects thetransfer switch to the circuit board.The terminal board provides the following connectionpoints:A. UTILITY 1 and UTILITY 21. Connect to identically marked terminals on atransfer switch terminal board.B. 23 and 15B1. Connect to identically numbered terminals onthe terminal board of the transfer switch.2. This circuit connects the circuit board to thetransfer relay coil in the transfer switch.TERMINAL STRIP0N1 N215B23Figure 1. Terminal Stripcircuit BoardThe circuit board controls all standby electric systemoperations including (a) engine startup, (b) enginerunning, (c) automatic transfer, (d) automatic retrans-fer, and (e) engine shutdown. In addition, the circuitboard performs the following functions:• Delivers “field boost” current to the generator rotorwindings (see “Field Boost Circuit” in Section 2.2).• Starts and “exercises” the generator once everyseven days.• Provides automatic engine shutdown in the event oflow oil pressure, high oil temperature, overspeed,no RPM sense, overcrank, or low battery.An 18-pin and a 4-pin connector are used to inter-connect the circuit board with the various circuits ofthe DC systems. Connector pin numbers, associatedwires and circuit functions are listed in the CHART onthe next page.If the Utility sensing voltage drops below a presetvalue, circuit board action will initiate automaticgenerator startup and transfer to the “Standby”source side.The crank relay and fuel solenoid valve are energizedby circuit board action at the same time.DIGITAL INPUT/OUTPUT FUNCTIONS:Postion Digital inputs Digital outputs1 Low Oil Pressure Not Used2 High Temperature Not Used3 Internal Use Not Used4 Internal Use Not Used5 Internal Use Fuel6 Not Used Starter7 Auto Ignition8 Manual Transfer* DaNGEr: tHE GENErator ENGiNE WillcraNK aND start WHEN tHE 7-DaYEXErcisEr sWitcH is actuatED. tHE uNitWill also craNK aND start EVErY 7DaYs tHErEaftEr, oN tHE DaY aND at tHEtimE of DaY tHE sWitcH Was actuatED.auto-oFF-manual SWitchThis 3-position switch permits the operator to (a)select fully automatic operation, (b) start the generatormanually, or (c) stop the engine and prevent automaticstartup. Switch terminals are shown pictorially andschematically in Figure 6, below.Page 96Part 4 DC CONTROLsEctioN 4.1DEscriPtioN aND comPoNENts0G9266revA.indd 96 10/15/2008 11:27:49 AM
