Generac Power Systems 65, 55, 75 manual Test 3- Test Excitation Circuit Breaker, Governor Adjustment

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Section 7

DIAGNOSTIC TESTS

GOVERNOR ADJUSTMENT

1.Loosen the GOVERNOR CLAMP BOLT.

2.Push Spring end of GOVERNOR LEVER clockwise to wide open throttle position of lever.

a.Hold the GOVERNOR LEVER at wide open throttle and, with a pair of pliers, rotate the GOVERNOR SHAFT fully clockwise (CW). Use a minimum amount of force against the gover- nor shaft.

b.While holding the GOVERNOR SHAFT fully clockwise and the GOVERNOR LEVER at wide open throttle, tighten the GOVERNOR CLAMP BOLT to 70 inch-pounds (8 N-m).

3.Start engine, let it stabilize and warm up at no-load.

4.Turn the ADJUSTER NUT to obtain a frequency reading of 62 Hertz.

5.Determine if the GOVERNOR SPRING is properly located in the slot of the GOVERNOR LEVER as follows:

a.If droop is excessive, move the GOVERNOR SPRING down one slot on LEVER.

b. For greater stability, move the GOVERNOR SPRING up one slot on LEVER.

6.After repositioning the SPRING on a LEVER slot, recheck fre- quency reading and, if necessary, readjust ADJUSTER NUT to obtain 62 Hertz at no-load.

7.When frequency is correct at no-load, check the AC voltage reading. If voltage is incorrect, the voltage regulator may require adjustment. See “VOLTAGE ADJUSTMENT,” Page 10.

TEST 3- TEST EXCITATION CIRCUIT

BREAKER

DISCUSSION:

This circuit breaker (CB3) is normally closed and self- resetting. It will open in the event of excessive current from the Stator excitation (DPE) winding. The circuit breaker should re-close or reset automatically after it cools down (takes approximately two minutes).

When the breaker (CB3) is open, excitation current to the Regulator (and to the Rotor) will be lost. The unit's AC output voltage will then drop to a value that is commensurate with the Rotor's residual magnetism (about 5-12 volts AC). This test will determine if the breaker has failed in its open position.

PROCEDURE:

Note: After running the unit, allow two minutes for the breaker to reset.

1.Set a volt-ohm-milliammeter (VOM) to its “Rx1” scale and zero the meter.

Figure 7-2. – Excitation “DPE” Circuit Breaker

2.In the generator panel, locate the excitation circuit breaker. Disconnect Wire 2 and Wire 2A from the breaker terminals.

3.Connect the meter test leads across the two circuit breaker (CB3) terminals. The meter should indicate “continuity”.

RESULTS:

1.If the meter did NOT read “continuity”, replace the excitation (DPE) circuit breaker (CB3), and go to Test 4.

2.If “continuity” was indicated, go to Test 4.

TEST 4- FIXED EXCITATION TEST/ROTOR

AMP DRAW

DISCUSSION:

The fixed excitation test consists of applying battery voltage (12 VDC) to the Rotor windings. This allows that portion of the excitation circuit between the Voltage Regulator and the Rotor (including the Rotor itself) to be checked as a possible cause of the prob- lem. When battery voltage is applied to the Rotor, the resulting magnetic field around the Rotor should induce a Stator power winding voltage equal to about one-half the unit's rated output voltage.

Figure 7-3. – Fixed Excitation Test

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Contents Diagnostic Repair Manual Replacement Parts SafetyTable of Contents Section Exploded Views / Part Numbers Section Specifications & ChartsElectromagnetic Induction MagnetismElectromagnetic Fields More Sophisticated AC Generator Simple AC GeneratorGenerator Operating Diagram Line Breakers 120 Volts only Field BoostGenerator AC Connection System Reconnection for Dual Voltage Output Connection for 120 Volts OnlyStator Assembly Rotor AssemblyBrush Holder Battery Charge ComponentsExcitation Circuit Components GeneralCrankcase Breather Adjustment ProcedureVoltage Regulator DescriptionInstall oil vapor collector and retainer Install BreatherControl Panel Component Identification Check BreatherEffects of Dirt and Moisture Cleaning the GeneratorInsulation Resistance Testers Drying the GeneratorStator Insulation Resistance Brushing and Vacuum CleaningCloth or Compressed AIR Stator SHORT-TO-GROUND TestsTesting Stator Insulation Testing Rotor InsulationTesting Rotor Insulation MegohmmeterVOM MetersMeasuring AC Voltage Measuring DC VoltageMeasuring Resistance Measuring AC FrequencyMeasuring Current Ohms LAW Electrical UnitsAmpere VoltCircuit CONDITION- Rest IntroductionOperational Analysis Circuit CONDITION- Priming Circuit CONDITION- Cranking Choke Heater CH Circuit CONDITION-RUNNINGCircuit CONDITION- Shutdown Sure Switch LOP Circuit CONDITION- Fault ShutdownRecommended Battery BatteryBattery Cables Engine Controller Circuit BoardAMP Fuse Fuel Primer SwitchSTART-STOP Switch Starter Contactor Relay Starter Motor Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Test 1- Check NO-LOAD Voltage Frequency ProcedureTest 2- Check Engine Governor DiscussionTest 3- Test Excitation Circuit Breaker Governor AdjustmentTest 4- Fixed Excitation TEST/ROTOR AMP Draw If continuity was indicated, go to TestRe-connect Wire 11 and Wire 22 to the Voltage Regulator Test 5- Wire ContinuitySet the VOM to measure AC voltage Set a VOM to its Rx1 scaleIf field boost checks good, replace the Voltage Regulator Test 6- Check Field BoostTest 7 Test Stator DPE Winding Across Wires Ohms Test 8- Check Sensing Leads / Power Windings11S 22S Model OhmsTest 10 Check Brushes & Slip Rings Test 9- Check Brush LeadsTance Tests Procedure Test 11- Check Rotor AssemblyTest 12 Check Main Circuit Breaker Replace the Rotor if it fails the testTest 16 Check Battery Charge Rectifier Test 15 Check Battery Charge OutputBattery Charge Rectifier BCR is a full wave rectifier Test 13- Check Load Voltage FrequencyShort to Ground 10. Battery Charge RectifierSet a VOM to read battery voltage 12 VDC Test 19- Test Primer SwitchAlso see Fuel Primer Switch, Test 18 TRY Cranking the Engine13. The LPG Fuel Solenoid FS Test 20- Check Fuel PumpTest 21- Check 7.5 AMP Fuse Test 22- Check Battery & CablesTest 23- Check Power Supply to Circuit Board 17. Start-Stop Switch Test 24 Check START-STOP SwitchSet a VOM to measure DC voltage 12 VDC Test 26- Check Starter Contactor RelayConditions Affecting Starter Motor Performance Test 26A Check Starter ContactorTest 27 Check Starter Motor Tools for Starter Performance Test Checking the PinionMeasuring Current TachometerTest 28- Check Fuel Supply Testing Starter MotorTest Bracket Remove Starter MotorDiscussion LPG Models 28 LP Gas Carburetion DiagramTest 30 Check Wire Test 29 Check Wire 14 Power SupplyBattery voltage is not measured, proceed to Step Crank the engine. The meter should indicate battery voltageTest 32 Check Ignition Spark Test 31 Check Fuel Solenoid Gasoline ModelsConclusion No cylinder is weakest of the two cylinders Cylinder Balance TestTest 33 Check Spark Plugs Test 34 Check and Adjust Ignition Magnetos37. Setting Ignition Magneto Armature Air Gap Adjusting Valve Clearance Test 35 Check Valve AdjustmentChecking Flywheel Magnet Flywheel KEYTest 37 Check Choke Solenoid Install Rocker ARM CoverTest 36 Check Carburetion 43. Connector Down Test / Compression Test Adjust the regulated pressure on the gauge to 80 psiRepeat Steps 1 through 8 on remaining cylinder Check CompressionIf all steps check GOOD, go to Test Test 39 Check OIL Pressure SwitchTest 40 Test OIL Temperature Switch Short to Ground Test 41 Test Choke HeaterTest 42 Check LPG Fuel Solenoid 49. Fuel Solenoid ENCLOSURE/PANEL Removal Major DisassemblyStator Removal Rotor RemovalStarter Removal Belt TensioningEngine Removal FLYWHEEL/MAGNETO Removal Page Section Exploded Views / Part Numbers Part NO. QTY Description Enclosure Drawing No E1011-B QTY Description Sheet Metal Drawing No E1012-E Flywheel Assy GT-990 QTY DescriptionControl Panel Drawing No E1013-A Switch Spdt ON-MOM-ON Wire ASM GRD STD ConnSwitch 6A Spdt Not Shown PANEL, TOP ControlTwin Engine Drawing No E1014-B ASSEMBLY, Breather ASSEMBLY, Crankcase RVASSEMBLY, Head #1 ASSEMBLY, OIL Fill CAPLP Regulator Drawing No E1530 Washer Flat M4 CASTING, Twin Regulator HousingSOLENOID, Twin Regulator SPRING-SOLENOID PlungerSpecifications & Charts Nominal Resistances of Generator Windings AT 68F Generator SpecificationsEngine Speeds and Voltage Specifications Page Electrical Data Electrical Data PO BOX 297 WHITEWATER, WI

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