Why generators show "no ac output voltage": 21 documented causes and brand-specific fixes, compiled across 7 manufacturers.
Main breaker(s) open.
1 brand- Generac: Close main breaker(s).
Main breaker(s) open
1 brand- Generac: 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact an authorized service facility.; 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact authorized service facility.
Transfer switch (if so equipped) is set to wrong position
1 brand- Generac: 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact an authorized service facility.; 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact authorized service facility.
Failure in vehicle electrical system
1 brand- Generac: 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact an authorized service facility.; 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact authorized service facility.
Generator component failure
1 brand- Generac: 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact an authorized service facility.; 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact authorized service facility.
1. Check circuit breaker.
1 brand- Generac: 1. Reset to ON or CLOSED.
The line circuit breaker is OFF.<br>
1 brand- Orion: 1. Rnd out why the circuit breaker was turned OFF, make sure it is safe to reconnect power, and then throw the circuit breaker ON.<br>2. Shut down the set and service as necessary to dear the short drcuit or ground fault that caused tripping, and then RESET the drcuit breaker and start the set.<br>3. Shut down the set, make sure the power output lines from the set have been disconnected from all other sources of power, attempt to RESET the drcuit breaker and throw it ON and check for electrical continuity across each line contact. Replace the drcuit breaker if there is measurable resistance across any contact.<br>4. RESET the drcuit breaker. If it keeps tripping, troubleshoot according to Trouble heading.
The line circuit breaker has TRIPPED.<br>
1 brand- Orion: 1. Rnd out why the circuit breaker was turned OFF, make sure it is safe to reconnect power, and then throw the circuit breaker ON.<br>2. Shut down the set and service as necessary to dear the short drcuit or ground fault that caused tripping, and then RESET the drcuit breaker and start the set.<br>3. Shut down the set, make sure the power output lines from the set have been disconnected from all other sources of power, attempt to RESET the drcuit breaker and throw it ON and check for electrical continuity across each line contact. Replace the drcuit breaker if there is measurable resistance across any contact.<br>4. RESET the drcuit breaker. If it keeps tripping, troubleshoot according to Trouble heading.
The line circuit breaker is faulty.<br>
1 brand- Orion: 1. Rnd out why the circuit breaker was turned OFF, make sure it is safe to reconnect power, and then throw the circuit breaker ON.<br>2. Shut down the set and service as necessary to dear the short drcuit or ground fault that caused tripping, and then RESET the drcuit breaker and start the set.<br>3. Shut down the set, make sure the power output lines from the set have been disconnected from all other sources of power, attempt to RESET the drcuit breaker and throw it ON and check for electrical continuity across each line contact. Replace the drcuit breaker if there is measurable resistance across any contact.<br>4. RESET the drcuit breaker. If it keeps tripping, troubleshoot according to Trouble heading.
Reid circuit breaker CB21 has TRIPPED
1 brand- Orion: 1. Rnd out why the circuit breaker was turned OFF, make sure it is safe to reconnect power, and then throw the circuit breaker ON.<br>2. Shut down the set and service as necessary to dear the short drcuit or ground fault that caused tripping, and then RESET the drcuit breaker and start the set.<br>3. Shut down the set, make sure the power output lines from the set have been disconnected from all other sources of power, attempt to RESET the drcuit breaker and throw it ON and check for electrical continuity across each line contact. Replace the drcuit breaker if there is measurable resistance across any contact.<br>4. RESET the drcuit breaker. If it keeps tripping, troubleshoot according to Trouble heading.
ENGINE RUNNING RATED RPM
1 brand- Cummins/Onan: Is the Exciter Circuit Breaker (CB21) on the meter panel in the “ON” position? Switch CB21 to the “ON” position. Is the AC voltage measured at terminals 1 and 2 on voltage regulator (VR21) printed circuit board 5 to 10 volts? Is the AC voltage measured at terminals 11 and 12 on VR21 5 to 10 volts? Replace reactor assembly (L21). Is the DC voltage measured at terminals + and - on Rectifier Bridge (CR21) 5 to 10 volts? Shut down generator set. Check continuity between terminal 2 on VR21 and T8 on generator, between terminal 1 on VR21 and T7 on generator. If no continuity exists between VR21-1 and T7 (CB21-ON) apply a shorting jumper across CB21. Is continuity obtained? Replace circuit breaker CB21. Check for loose or broken wires on VR21, CR21, reference voltage transformer (T21), generator bus-bars and terminal board (TB21) in control box. Secure or repair where necessary. If repairs have been made, restart engine. Are diodes CR1, CR2 and CR3 on CR21 assembly good? Are SCRs 4 and 5 in CR21 good? Fault probably lies with a defective component on VR21. Replace voltage regulator VR21. Start engine. Place CB21 in “OFF” position. Using method prescribed under “M” in procedure section flash the exciter field to restore residual magnetism. Place CB21 ON. Shut off engine. Is the exciter field winding OK? Are the rotating diodes CR1, through CR6 on the exciter rotor OK?; Page 13
Voltage regulator is inoperative.
1 brand- Cummins/Onan: Refer to Initial Start and Checks, and Adjustments sections of your Installation Manual for voltage check and adjustment procedures. Contact your distributor if voltage build-up is still a problem.
Field breaker is tripped. Reset breaker. Contact an authorized service center if voltage buildup causes breaker to trip.
1 brandOpen AC circuit breaker due to an overload
1 brand- Cummins/Onan: Remove all loads, re-set circuit breaker, check tools or appliances being used for defects. Do not exceed generator set rated load specifications.
Open AC circuit breaker
1 brand- Cummins/Onan: 1. Locate cause of overload and correct as required. Reset breaker. 2. Check for continuity and correct if circuit is open. Check for defective receptacle/extension cords. 3. Test Rotor coil. 4. Test stator main coil.