Generac Power Systems 7 kW NG Repair Manual page 4

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
PART 3 - Transfer Switch ..................................................59
Section 3.1 - Description and Components ....................... 60
Introduction .......................................................... 60
Enclosure ............................................................. 60
Transfer Switch Contactor ..................................... 61
Transfer Relay ....................................................... 61
Neutral Lug ........................................................... 62
Manual Transfer Handle ........................................ 62
Customer Connections ......................................... 62
Fuse Holder .......................................................... 63
Section 3.2 - Operational Analysis .................................... 64
Utility Source Voltage Available.............................. 64
Utility Source Voltage Failure ................................. 65
Transferring to Standby ......................................... 66
Transferred to Standby .......................................... 67
Utility Restored ..................................................... 68
Utility Restored, Transferring back to Utility ............ 69
Utility Restored, Transferred back to Utility ............ 70
Transferred back to Utility, Generator Shutdown ..... 71
Section 3.3 - Troubleshooting Flowcharts ......................... 73
Introduction .......................................................... 73
Problem 6 - In Automatic Mode,
No Transfer to Standby ...................... 73
Problem 7 - In Automatic Mode, Generator Starts
When Loss of Utility Occurs,
Generator Shuts Down When Utility
Returns, but There Is No Retransfer
to Utility or Generator Transfers to
Standby During Exercise or in
Manual Mode With Utility Available ..... 74
Problem 8 - Unit Starts and Transfers When
Utility Power is Available ................... 74
Problem 9 - Blown F1 or F2 Fuse .......................... 74
Problem 10 - Blown T1 Fuse ................................ 74
Page 2
Section 3.4 - Diagnostic Tests .......................................... 76
Introduction .......................................................... 76
Safety ................................................................... 76
Transfer Switch Troubleshooting .......................... 76
Test 20 - Check Voltage at
Terminal Lugs E1 and E2 ....................... 76
Test 21 - Check Manual Transfer
Switch Operation ................................... 77
Test 22 - Check 23 and 194 Circuit ...................... 78
Test 23 - Test Transfer Relay ................................ 79
Test 24 - Test Standby Control Circuit ................... 79
Test 25 - Check Wire 23 ....................................... 81
Test 26 - Utility Control Circuit ............................. 83
Test 27 - Test Limit Switches ................................ 83
Test 28 - Check Fuses F1 and F2 .......................... 84
Test 29 - Check Fuse F3 ...................................... 84
Test 30 - Check Main Circuit Breaker .................... 84
Test 32 - Check N1 and N2 Wiring ........................ 85
Test 33 - Check N1 and N2 Voltage ...................... 85
Test 34 - Check Utility Sensing Voltage
at the Circuit Board ................................ 86
Test 35 - Check Utility SENSE Voltage ................... 86
Test 36 - Check T1 Wiring .................................... 86
PART 4 - Engine/DC Control ..............................................89
Section 4.1 - Description and Components ....................... 90
Introduction .......................................................... 90
Customer Connection ........................................... 90
Controller ............................................................. 90
LED Display .......................................................... 90
Battery Charger .................................................... 90
7.5 Amp Fuse ....................................................... 91
Starter Contactor Relay/Solenoid .......................... 91
Common Alarm Relay .......................................... 92
Connector Pin Descriptions ................................... 92
Menu System Navigation ...................................... 93
Section 4.2 - Engine Protective Devices ............................ 94
Introduction .......................................................... 94
Low Battery Warning ............................................ 94
Low Oil Pressure .................................................. 94
High Temperature Switch ...................................... 94
Overspeed ............................................................ 94
RPM Sensor Failure .............................................. 94
Overcrank ............................................................. 94
Under-frequency ................................................... 95
Clearing an Alarm ................................................. 95
Section 4.3 - Operational Analysis .................................... 96
Introduction .......................................................... 96
Utility Source Voltage Available.............................. 96