Generac Power Systems 75 Test 1- Check NO-LOAD Voltage Frequency, Test 2- Check Engine Governor

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Section 7

DIAGNOSTIC TESTS

INTRODUCTION

The “Diagnostic Tests” in this chapter may be per- formed in conjunction with the “Flow Charts” of Section 6. Test numbers in this chapter correspond to the numbered tests in the “Flow Charts”.

Tests 1 through 17 are procedures Involving prob- lems with the generator's AC output voltage and fre- quency (Problems 1 through 4 in the “Flow Charts”).

Tests 18 through 42 are procedures involving prob- lems with engine operation (Problems 5 through 9 in the “Troubleshooting Flow Charts”).

You may wish to read Section 4, “Measuring Electricity”.

NOTE: Test procedures in this Manual are not necessarily the only acceptable methods for diag- nosing the condition of components and circuits. All possible methods that might be used for sys- tem diagnosis have not been evaluated. If you use any diagnostic method other than the method presented in this Manual, you must ensure that neither your safety nor the product's safety will be endangered by the procedure or method you have selected.

TEST 1- CHECK NO-LOAD VOLTAGE AND

FREQUENCY

DISCUSSION:

The first step in analyzing any problem with the AC generator is to determine the unit's AC output voltage and frequency. Once that has been done, you will know how to proceed with specific diagnostic tests.

PROCEDURE:

1.Set a volt-ohm-milliammeter (VOM) to read AC voltage. Connect the meter test leads across customer connection leads T1 (Red) and T2 (White).

2.Disconnect or turn OFF all electrical loads. Initial checks and adjustments are accomplished at no-load.

3.Start the engine, let it stabilize and warm up.

4.Read the AC voltage.

5.Connect an AC frequency meter across AC output leads T1 (Red) and T2 (White). Repeat the above procedure.

RESULTS:

For units rated 60 Hertz, no-load voltage and frequen- cy should be approximately 122-126 VAC and 61-63 Hertz respectively.

1.If AC voltage and frequency are BOTH correspondingly high or low, go to Test 2.

2.If AC frequency is good but low or residual voltage is indicated, go to Test 3.

3.If AC output voltage and frequency are both “zero”, go to Test 12.

4.If the no-load voltage and frequency are within the stated limits, go to Test 13.

NOTE: The term “low voltage” refers to any volt- age reading that is lower than the unit's rated voltage. The term “residual voltage” refers to the output voltage supplied as a result of Rotor resid- ual magnetism (approximately 5-12 VAC).

TEST 2- CHECK ENGINE GOVERNOR

DISCUSSION:

Rotor operating speed and AC output frequency are proportional. The generator will deliver a frequency of 60 Hertz at 3600 Rotor rpm or 62 Hertz at 3720 Rotor rpm.

The Voltage Regulator should be adjusted to deliver 120 VAC (line-to-neutral) at a frequency of 60 Hertz or 124 VAC (line-to-neutral at 62 Hertz. It is apparent that, if governed speed is high or low, AC frequency and voltage will be correspondingly high or low. Governed speed at no-load is usually set slightly above the rated speed of 60 Hertz (to 62 Hertz), to prevent excessive rpm, frequency and voltage droop under heavy electrical loading.

Figure 7-1. – Governor Adjustment Points

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Contents Diagnostic Repair Manual Safety Replacement PartsTable of Contents Section Specifications & Charts Section Exploded Views / Part NumbersElectromagnetic Fields MagnetismElectromagnetic Induction Simple AC Generator More Sophisticated AC GeneratorGenerator Operating Diagram Generator AC Connection System Field BoostLine Breakers 120 Volts only Connection for 120 Volts Only Reconnection for Dual Voltage OutputRotor Assembly Stator AssemblyBattery Charge Components Brush HolderExcitation Circuit Components GeneralAdjustment Procedure Crankcase BreatherVoltage Regulator DescriptionInstall Breather Install oil vapor collector and retainerControl Panel Component Identification Check BreatherCleaning the Generator Effects of Dirt and MoistureInsulation Resistance Testers Drying the GeneratorBrushing and Vacuum Cleaning Stator Insulation ResistanceCloth or Compressed AIR Stator SHORT-TO-GROUND TestsTesting Rotor Insulation Testing Stator InsulationTesting Rotor Insulation MegohmmeterMeters VOMMeasuring AC Voltage Measuring DC VoltageMeasuring Current Measuring AC FrequencyMeasuring Resistance Electrical Units Ohms LAWAmpere VoltOperational Analysis IntroductionCircuit CONDITION- Rest Circuit CONDITION- Priming Circuit CONDITION- Cranking Circuit CONDITION-RUNNING Choke Heater CHCircuit CONDITION- Shutdown Circuit CONDITION- Fault Shutdown Sure Switch LOPBattery Recommended BatteryBattery Cables Engine Controller Circuit BoardSTART-STOP Switch Fuel Primer 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 Procedure Test 1- Check NO-LOAD Voltage FrequencyTest 2- Check Engine Governor DiscussionGovernor Adjustment Test 3- Test Excitation Circuit BreakerTest 4- Fixed Excitation TEST/ROTOR AMP Draw If continuity was indicated, go to TestTest 5- Wire Continuity Re-connect Wire 11 and Wire 22 to the Voltage RegulatorSet the VOM to measure AC voltage Set a VOM to its Rx1 scaleTest 7 Test Stator DPE Winding Test 6- Check Field BoostIf field boost checks good, replace the Voltage Regulator Test 8- Check Sensing Leads / Power Windings Across Wires Ohms11S 22S Model OhmsTest 9- Check Brush Leads Test 10 Check Brushes & Slip RingsTest 11- Check Rotor Assembly Tance Tests ProcedureTest 12 Check Main Circuit Breaker Replace the Rotor if it fails the testTest 15 Check Battery Charge Output Test 16 Check Battery Charge RectifierBattery Charge Rectifier BCR is a full wave rectifier Test 13- Check Load Voltage Frequency10. Battery Charge Rectifier Short to GroundTest 19- Test Primer Switch Set a VOM to read battery voltage 12 VDCAlso see Fuel Primer Switch, Test 18 TRY Cranking the EngineTest 20- Check Fuel Pump 13. The LPG Fuel Solenoid FSTest 23- Check Power Supply to Circuit Board Test 22- Check Battery & CablesTest 21- Check 7.5 AMP Fuse Test 24 Check START-STOP Switch 17. Start-Stop SwitchTest 26- Check Starter Contactor Relay Set a VOM to measure DC voltage 12 VDCTest 27 Check Starter Motor Test 26A Check Starter ContactorConditions Affecting Starter Motor Performance Checking the Pinion Tools for Starter Performance TestMeasuring Current TachometerTesting Starter Motor Test 28- Check Fuel SupplyTest Bracket Remove Starter Motor28 LP Gas Carburetion Diagram Discussion LPG ModelsTest 29 Check Wire 14 Power Supply Test 30 Check WireBattery voltage is not measured, proceed to Step Crank the engine. The meter should indicate battery voltageTest 31 Check Fuel Solenoid Gasoline Models Test 32 Check Ignition SparkCylinder Balance Test Conclusion No cylinder is weakest of the two cylindersTest 34 Check and Adjust Ignition Magnetos Test 33 Check Spark Plugs37. Setting Ignition Magneto Armature Air Gap Test 35 Check Valve Adjustment Adjusting Valve ClearanceChecking Flywheel Magnet Flywheel KEYTest 36 Check Carburetion Install Rocker ARM CoverTest 37 Check Choke Solenoid 43. Connector Adjust the regulated pressure on the gauge to 80 psi Down Test / Compression TestRepeat Steps 1 through 8 on remaining cylinder Check CompressionTest 40 Test OIL Temperature Switch Test 39 Check OIL Pressure SwitchIf all steps check GOOD, go to Test Test 42 Check LPG Fuel Solenoid Test 41 Test Choke HeaterShort to Ground 49. Fuel Solenoid Major Disassembly ENCLOSURE/PANEL RemovalStator Removal Rotor RemovalEngine Removal Belt TensioningStarter 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 QTY Description Flywheel Assy GT-990Control Panel Drawing No E1013-A Wire ASM GRD STD Conn Switch Spdt ON-MOM-ONSwitch 6A Spdt Not Shown PANEL, TOP ControlTwin Engine Drawing No E1014-B ASSEMBLY, Crankcase RV ASSEMBLY, BreatherASSEMBLY, Head #1 ASSEMBLY, OIL Fill CAPLP Regulator Drawing No E1530 CASTING, Twin Regulator Housing Washer Flat M4SOLENOID, Twin Regulator SPRING-SOLENOID PlungerSpecifications & Charts Generator Specifications Nominal Resistances of Generator Windings AT 68FEngine Speeds and Voltage Specifications Page Electrical Data Electrical Data PO BOX 297 WHITEWATER, WI

65, 75, 55 specifications

Generac Power Systems has established itself as a leader in power generation, offering a range of high-performance generators suited for residential and commercial applications. Among its lineup, the Generac 55, 65, and 75 kW generators stand out for their reliability, efficiency, and advanced features.

The Generac 55 kW generator is designed to provide a powerful backup solution for medium to large homes or small businesses. It features a robust engine that delivers dependable performance while maintaining fuel efficiency. One of its key characteristics is the True Power Technology, which produces clean and stable power, ensuring that sensitive electronic devices run smoothly without risk of damage. This generator is equipped with a fully automatic transfer switch, allowing for seamless power transition during outages, with minimal disruption.

Moving to the 65 kW model, it offers increased capacity while retaining the fundamental qualities of the 55 kW version. This unit is particularly suited for larger homes or commercial applications that require greater power demands. The 65 kW generator utilizes Generac’s G-Force engine, known for its durability and reduced maintenance needs. Advanced features such as remote monitoring capabilities allow users to check the generator's status from anywhere, providing peace of mind and convenience.

The 75 kW generator takes performance to the next level, making it ideal for even more significant power needs. It is engineered for both quiet operation and enhanced performance, accommodating a wide range of requirements from residential to larger commercial operations. The 75 kW model includes a full-load voltage regulation system that maintains stable power output under varying loads, safeguarding appliances and equipment.

All three models incorporate advanced air-cooled technology, which enhances their efficiency and operational lifespan. Additionally, their corrosion-resistant enclosures ensure durability even in harsh weather conditions, making them suitable for diverse environments. The intuitive LCD display on each unit provides critical information, including runtime hours and maintenance reminders, empowering users with easy access to the generator's performance data.

Overall, Generac Power Systems' 55, 65, and 75 kW generators represent a commitment to quality, reliability, and innovation in backup power solutions. They are designed to meet the demands of modern power consumption while ensuring peace of mind through robust engineering and advanced technology. Whether for home use or commercial applications, these generators provide an effective means to stay prepared for unexpected power outages.
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