Part 2 - Ac Generators - Generac Power Systems 7 kW NG Repair Manual

PART 2
AC GENERATORS
Air-cooled, Automatic
Standby Generators
Section 2.1 - Description and Components ....................... 40
Introduction .......................................................... 40
Engine-Generator Drive System ............................. 40
Alternator Assembly ............................................. 40
Other AC Generator Components .......................... 40
Section 2.2 - Operational Analysis .................................... 42
Rotor Residual Magnetism .................................... 42
Field Boost ........................................................... 42
Operation .............................................................. 42
Section 2.3 - Troubleshooting Flowcharts ......................... 44
Introduction .......................................................... 44
Problem 1 - Generator Shuts Down
for Under-voltage .............................. 44
Problem 2 - Generator Shuts Down
for High Voltage ................................ 45
Problem 3 - Voltage and Frequency Drop
Excessively When Loads Are Applied . 46
TABLE OF CONTENTS
SECTION TITLE
2.1 Description and Components
2.2 Operational Analysis
2.3 Troubleshooting Flow Charts
2.4 Diagnostic Tests
Section 2.4 - Diagnostic Tests .......................................... 47
Introduction .......................................................... 47
Safety ................................................................... 47
AC Troubleshooting............................................... 47
Test 1 - Check AC Output Voltage ......................... 47
Test 3 - Calibrate Voltage ...................................... 48
Test 4 - Fixed Excitation Test/
Rotor Amp Draw Test ............................... 48
Test 5 - Test Sensing CircuitWires 11 and 44 ........ 51
Test 6 - Test Excitation WindingCircuit 2 and 6 ...... 52
Test 7 - Test the Stator with a VOM ....................... 52
Test 8 - Resistance Check of Rotor Circuit ............ 54
Test 9 - Check Brushes and Slip Rings ................. 54
Test 10 - Test Rotor Assembly .............................. 55
Test 11 - Check AC Output Frequency ................... 55
Test 12 - Check Stepper Motor Control ................. 56
Test 14 - Check Voltage and
Frequency under Load ........................... 57
Test 15 - Check for an Overload Condition ............ 57
Test 16 - Check Engine Condition ......................... 57
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44
47
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