Voltage Variations This generator set must be run at its proper speed to obtain the correct electrical power at its output. All engines have a tendency to slow down when a load is applied to it. The engine governor is designed to hold the operating speed as nearly constant as possible. When the electrical load is increased, the engine is more heavily loaded and engine speed drops slightly. This slight decrease in engine speed results in a slight decrease in generator voltage and frequency output. This voltage and frequency variation has no appreciable effect in the operation of motors, lights, and most appliances and tools. However, timing devices and clocks will not keep perfect time when used on this generator.
Reduced voltage to the load can also be caused by using the wrong extension cord. Small diameter wire will have a voltage drop across the cord when current flows through the wire. This voltage drop can be very significant over long cord lengths. Always use the proper wire size (gauge wire size) for the extension cord to minimize the voltage drop at rated current draw.
Problems and Solutions
Some of the more common problems are listed in Table
Table 5-2 Troubleshooting Guide
Problem | Possible Cause | Remedy |
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Engine will not start | No fuel. | Check that fuel valves are ON. Check fuel level in fuel tank. |
| Restricted air flow. | Check/replace air filter. |
| No spark. | Check/replace spark plug(s). Verify engine switch is in |
| Low oil level. | Oil sensor will prevent engine starting if oil level is low. |
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|
|
Engine will not crank (electric start) | Dead battery. | Remove battery and trickle charge or replace with new battery. |
|
| Never Jump Start. |
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|
Engine starts but will not run smoothly | Fuel or ignition problem | Have engine serviced. |
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Engine overheats | Excessive load | Remove one or more electrical loads. |
| Debris or dirt buildup on engine | Remove debris. Clean engine surfaces to allow cooling. |
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|
|
No output voltage | Ciruit Breaker tripped or defective. | Reset circuit breaker or replace if required. |
| Loss of residual magnetism in exciter | Flash field. |
| field poles. | Check for continuity in windings. Return to factory for repair if open. |
| Open in stator windings | |
| Defective exciter circuit. | Check/replace diode and capacitor and flash the field. |
|
|
|
Output voltage varies | Irregular speed (fixed speed mode) | Check engine for malfunction or load for fluctuation |
| Fluctuating speed (fixed speed mode) | Stabilize load. The addition of a lamp load (resistance load) may |
|
| compensate partially for load changes caused by intermittent motor |
|
| operation. Do not overload. |
Loose terminal or load connections Defective bearing (uneven air gap)
Verify all connections are proper and check tighness torque of terminals.
Replace worn bearing
Low output voltage | Low engine speed |
| Excessive load |
| High resistance connections − |
| connections will be warm or hot |
| Shorted field |
| Low power factor |
Check that the Auto Idle switch is in OFF position.
Check engine for malfunction or system for overload. Reduce load. Verify all connections are proper and check tighness torque of terminals.
Test field coils for possible short by checking resistance with an ohmmeter or resistancebridge. Return rotor assembly to factory forrepair if alternator field coils are shorted.
Reduce inductive (motor) load. Some AC motors use about the same current regardless of load. Do not use motors of greater horsepower rating than is necessary to move the mechanical load.
High output voltage | Excessive speed (fixed speed mode) | Check engine for malfunction |
Electrical shock when frame is touched | Static charge. | Ground generator frame at local reference ground (see Section 3). |
| Grounded armature or field coil. | Return to factory for repair |
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MN2403 | Troubleshooting and Maintenance |
