Generac Power Systems 55, 75, 65 Test 9- Check Brush Leads, Test 10 Check Brushes & Slip Rings

Page 45

Section 7

DIAGNOSTIC TESTS

9.Connect the meter test leads across Stator lead 11P and frame ground. “Infinity” should be read.

10.Connect the meter test leads across Stator lead 33 and frame ground. The reading should be “Infinity”.

11.Connect the meter test leads across Stator leads Wire 11P and Wire 33. The reading should be “Infinity”.

12.Connect the meter test leads across Stator leads Wire 11P and Wire 66. The reading should be “Infinity”.

13.Connect the meter test leads across Stator leads Wire 33 and Wire 66. The reading should be “Infinity”.

14.Connect the meter test leads across Stator leads Wire 11P and Wire 2. The reading should be “Infinity”.

15.Connect the meter test leads across Stator leads Wire 33 and Wire 2. The reading should be “Infinity”.

RESULTS:

1.If the Stator passes all steps except Step 7, repair, re-connect or replace Sensing leads 11S and 22S.

2.Replace the Stator if it’s power windings fail the test. (Note Result No. 1).

3.If the Power Windings test good, perform the “Insulation Resistance Test” on Page 13.

Figure 7-6. – Stator Power Winding Leads

TEST 9- CHECK BRUSH LEADS

DISCUSSION:

In Test 4, if application of battery voltage to the Rotor did NOT result in an output of about one-half rated voltage, the brush leads could be one possible cause of the problem. This test will check Wires 4 and OK for an open circuit condition.

PROCEDURE:

1.Set a VOM to its “Rx1” scale and zero the meter.

2.Disconnect Wire 4 from the Voltage Regulator and from the Rotor brush terminal.

3.Connect the VOM test leads across each end of the wire. The meter should read “Continuity”.

4.Disconnect Wire OF from the Rotor Brush Terminal. Connect one meter test lead to Wire OF. Connect the other test lead to a clean frame ground. The meter should read “Continuity”.

RESULTS:

1.Repair, reconnect or replace any defective wire(s).

2.If wires check good, go to Test 10.

Figure 7-7. – Brush Leads

TEST 10 - CHECK BRUSHES & SLIP RINGS

DISCUSSION:

Brushes and slip rings are made of special materials that will provide hundreds of hours of service with little wear. However, when the generator has been idle for some time, an oxide film can develop on the slip rings. This film acts as an insulator and impedes the flow of excitation current to the Rotor.

If Test 4 resulted in less than one-half rated output voltage, it is possible that the brushes and slip rings are at fault.

PROCEDURE:

1.Gain access to the brushes and slip rings.

2.Remove Wire 4 from the positive (+) brush terminal.

3.Remove the ground wire (0F) from the negative (-) brush.

4.Remove the brush holder, with brushes.

5.Inspect the brushes for excessive wear, damage, cracks, chip- ping, etc.

6.Inspect the brush holder, replace if damaged.

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Contents Diagnostic Repair Manual Replacement Parts SafetyTable of Contents Section Exploded Views / Part Numbers Section Specifications & ChartsMagnetism Electromagnetic FieldsElectromagnetic Induction More Sophisticated AC Generator Simple AC GeneratorGenerator Operating Diagram Field Boost Generator AC Connection SystemLine Breakers 120 Volts only 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 AC Frequency Measuring CurrentMeasuring Resistance Ohms LAW Electrical UnitsAmpere VoltIntroduction Operational AnalysisCircuit CONDITION- Rest 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 BoardFuel Primer Switch START-STOP SwitchAMP Fuse 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 scaleTest 6- Check Field Boost Test 7 Test Stator DPE WindingIf field boost checks good, replace the Voltage Regulator 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 22- Check Battery & Cables Test 23- Check Power Supply to Circuit BoardTest 21- Check 7.5 AMP Fuse 17. Start-Stop Switch Test 24 Check START-STOP SwitchSet a VOM to measure DC voltage 12 VDC Test 26- Check Starter Contactor RelayTest 26A Check Starter Contactor Test 27 Check Starter MotorConditions Affecting Starter Motor Performance 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 KEYInstall Rocker ARM Cover Test 36 Check CarburetionTest 37 Check Choke Solenoid 43. Connector Down Test / Compression Test Adjust the regulated pressure on the gauge to 80 psiRepeat Steps 1 through 8 on remaining cylinder Check CompressionTest 39 Check OIL Pressure Switch Test 40 Test OIL Temperature SwitchIf all steps check GOOD, go to Test Test 41 Test Choke Heater Test 42 Check LPG Fuel SolenoidShort to Ground 49. Fuel Solenoid ENCLOSURE/PANEL Removal Major DisassemblyStator Removal Rotor RemovalBelt Tensioning Engine RemovalStarter 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

65, 75, 55 specifications

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