Voltage Output

[roadkingh1]

I have a 7.5 westerbeke and have a question. When the generator is running with no load my frequency is about 63 hertz +/- .75 hertz and the voltage is around 115v and varies between 115 and 117. Is that normal? Also, as I load down the generator the frequency will start to decrease till about 60.5 hertz at full load and the volage will be be around 128 volts. In the manual it states that the voltage should be about +/- 5% from no load. So if the no load voltage is 115 than the full load voltage should be 120.5v or 109.25v. Can anyone elaborate.

Thank you
Ted

 

[white glove]

I can say that 115 v to117v is normal at no load. I have a westerbeke 4.5 and I recently had to make some adjustments to engine speed due to ethanol. My understanding is as you load, the governor will try to spool up the engine to its rpm that supplies 60 cycles.As this happens the cycles will fluctuate slightly as speed fluctuates.When it's all said and done ,if the engine is running at its design rpm ,you should make 60 cycles. I made governor adjustments to allow the engine to run at load at no more than 120volts.The goal is maintaining 110 to 120 volts and no more.You may look at the throttle and make sure it is fully open at no load you may have to adjust the governor and limit controls so that you run at the correct engine speed.The engine speed is critical because if it is incorrect,you won't turn the rpms for the cycles you need and thus will have incorrect voltage.The adjustments are simple .I think this may just be an engine speed issue.

 

[fc3]

You are not that far out of spec. According to the Westerbeke factory service manual (publication number 544518) for my 4.5 BCGTC, which also covers the 7.2 BCGTC, and a few others for "Proper no-load but high loaded voltage" the probable cause is "RPM too high, regulate RPM." But if you're getting 60Hz, the the RPMs are OK. You might be able to take the RPMs down a bit and see if that helps.

Best regards,
Frank

 

[roadkingh1]

Thanks for the advise, now I will have something to do this weekend.

 

[roadkingh1]

I can say that 115 v to117v is normal at no load. I have a westerbeke 4.5 and I recently had to make some adjustments to engine speed due to ethanol. My understanding is as you load, the governor will try to spool up the engine to its rpm that supplies 60 cycles.As this happens the cycles will fluctuate slightly as speed fluctuates.When it's all said and done ,if the engine is running at its design rpm ,you should make 60 cycles. I made governor adjustments to allow the engine to run at load at no more than 120volts.The goal is maintaining 110 to 120 volts and no more.You may look at the throttle and make sure it is fully open at no load you may have to adjust the governor and limit controls so that you run at the correct engine speed.The engine speed is critical because if it is incorrect,you won't turn the rpms for the cycles you need and thus will have incorrect voltage.The adjustments are simple .I think this may just be an engine speed issue.

I have a question about the engine speed. I did fine that the adjustment to the throttle was out a little, but did not help my hertz. As I have stated, my frequency is around 63Hz with no load. There is a "Increase/Decrease" adjustment on the governor. Any further adjustment will not decrease the speed on the generator. Is there anything else on the generator that prevents me from decreasing the speed of my generator. I may have to invest in a tach. just to see if truely my generator is at 1800rpm. If it is at 1800rpm is there a reason my generator is operating that freq?

 

[fc3]

Reading frequency is a tachometer. 60 cycles per second x 60 seconds per minute = 3600 cycles per minute. 1 cycle for a 2 pole alternator = 1 RPM. A four pole altenator needs to run at half the RPMs to generate 60 Hz. Either something wrong with your adjustment procedure or you were not measuring the generator's output.

Note: The only exception to Hz follows RPM is on generators that use inverters as the greatly beloved honda generators do. The Westerbeke does not use an inverter.

Best regards,
Frank

 

[roadkingh1]

I have a question about the engine speed. I did fine that the adjustment to the throttle was out a little, but did not help my hertz. As I have stated, my frequency is around 63Hz with no load. There is a "Increase/Decrease" adjustment on the governor. Any further adjustment will not decrease the speed on the generator. Is there anything else on the generator that prevents me from decreasing the speed of my generator. I may have to invest in a tach. just to see if truely my generator is at 1800rpm. If it is at 1800rpm is there a reason my generator is operating that freq?

Reading frequency is a tachometer. 60 cycles per second x 60 seconds per minute = 3600 cycles per minute. 1 cycle for a 2 pole alternator = 1 RPM. A four pole altenator needs to run at half the RPMs to generate 60 Hz. Either something wrong with your adjustment procedure or you were not measuring the generator's output.

Note: The only exception to Hz follows RPM is on generators that use inverters as the greatly beloved honda generators do. The Westerbeke does not use an inverter.

Best regards,
Frank

Thanks for getting back to me. I took the governor off and empty the oil out last summer and refilled according the service manual. Aso in the manual it instructs you to check the throttle linkage with the engine off. It also has you check the correct engine speed at no load which is 1835 and 1800 at 60Hz. The only other adjustment is the one on the governor which is suppose to increase or decrease your engine speed. The only problem is that I can no longer achive that goal.

 

[fc3]

You're getting full throttle when you look past the choke plate down the carburetor's throat with the engine off? The throttle plate is perfectly vertical?

 

[roadkingh1]

You're getting full throttle when you look past the choke plate down the carburetor's throat with the engine off? The throttle plate is perfectly vertical?

Yes, The manual states that that with the engine off the the governor should hold the throttle wide open.