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Old 07-08-2022, 16:39   #1
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Generator Field Capacitor

We have a 8.5KW Paguro Generator that weíve been fighting to keep running since it was new. It currently has 200 hours on it and I have to replace the 35uf field capacitor about every 10 hours of run time. So basically every 6 months or so.

Iím wondering if there are high quality brands of run capacitors we should be buying to help with this issue. Are there good brands we should focus on?

Also, the capacitor is mounted inside the very tight sound enclosure. Iím wondering if I should extend the two wires and try mounting the capacitor outside the enclosure.

Does anyone have advice around this?
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Old 07-08-2022, 20:10   #2
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Re: Generator Field Capacitor

Your best bet is to extend and mount outside. Heat kills caps.
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Old 09-08-2022, 06:18   #3
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Re: Generator Field Capacitor

Do you have cap specs? Not paguro part number, but rather capacitor manufacturer part number....rybicon,nichicon are the two that make shitty electrolytics that tend to fail early.
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Old 09-08-2022, 06:32   #4
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Re: Generator Field Capacitor

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Do you have cap specs? Not paguro part number, but rather capacitor manufacturer part number....rybicon,nichicon are the two that make shitty electrolytics that tend to fail early.
Itís a Paguro generator. They just say 30uf 440v. I have been burning up the Titan Pro caps pretty quickly. I just extended the wires by 6 feet and mounted it outside the enclosure into an air conditioned area. Iím hoping the extending wires donít cause an issue but after a few hours itís still running okay.
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Old 09-08-2022, 06:36   #5
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Re: Generator Field Capacitor

Sounds like too high a ripple current issue.
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Old 09-08-2022, 15:03   #6
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Re: Generator Field Capacitor

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Sounds like too high a ripple current issue.
Iíll be honest, Iím not sure what that means.

Here is how the unit is operated (it has 200 hours on it).

Itís started with zero load and then after a minute or so, load is added. We can only run the unit to 60% load max but itís usually around 50%.

It runs at 3600 RPM, 60-61 Hz, and voltage is between 120 and 121.

When we shut it down, we remove all loads and the meter reads 0%, then we shut it down after about a minute running with no load.
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Old 09-08-2022, 15:10   #7
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Re: Generator Field Capacitor

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I’ll be honest, I’m not sure what that means.

Here is how the unit is operated (it has 200 hours on it).

It’s started with zero load and then after a minute or so, load is added. We can only run the unit to 60% load max but it’s usually around 50%.

It runs at 3600 RPM, 60-61 Hz, and voltage is between 120 and 121.

When we shut it down, we remove all loads and the meter reads 0%, then we shut it down after about a minute running with no load.
if there is high frequency current spikes , you can find that the ESR of the caps is too high ( Equivalent series resistance) equally if there is a DC component that can affect things

this causes caps to heat up , and fail even though their "label" ratings suggest they are within spec

you might consder a high quality one like https://connect.kemet.com:7667/gatew...274AC35400AA0J

This is a metallised film type and way better then cheaper electrolytic types often used , far more tolerant of excess circumstances
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Old 09-08-2022, 15:21   #8
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Re: Generator Field Capacitor

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if there is high frequency current spikes , you can find that the ESR of the caps is too high ( Equivalent series resistance) equally if there is a DC component that can affect things

this causes caps to heat up , and fail even though their "label" ratings suggest they are within spec
The loads are as follows:

4 Dometic air conditioners
1 Quick water heater
2 Cristec battery chargers
1 Splendide clothes washer (rarely run)

Plug in AC consumers are run through the inverter.

One thing that I just thought of is that even though we rarely run the washer/dryer, it does power up when the generator is started which means it is on (just in standby) when we shut the generator off.

Thinking about this, does that mean that field capacitor is trying to maintain 120 volts as the generator shuts down because of the tiny amount of current the washer is using? Maybe I should **** the breaker off for the washer.
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Old 09-08-2022, 15:22   #9
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Re: Generator Field Capacitor

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Itís a Paguro generator. They just say 30uf 440v. I have been burning up the Titan Pro caps pretty quickly. I just extended the wires by 6 feet and mounted it outside the enclosure into an air conditioned area. Iím hoping the extending wires donít cause an issue but after a few hours itís still running okay.


This is probably un needed advice because youíve changed a few but that capacitor is live and remains so for a while after shutdown so the remote mounting of it should be in an insulated box. You seem to be using a very good brand of capacitor already so I canít offer a better recommendation. Iím interested to see how this issue resolves.
Pete.
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Old 09-08-2022, 15:27   #10
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Re: Generator Field Capacitor

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This is probably un needed advice because youíve changed a few but that capacitor is live and remains so for a while after shutdown so the remote mounting of it should be in an insulated box. You seem to be using a very good brand of capacitor already so I canít offer a better recommendation. Iím interested to see how this issue resolves.
Pete.
Agreed! I always short them out with an insulated tool before handling. At the moment it is just zip tied to a bulkhead way out of the way but Iíll do a permanent safe mount if this corrects the issue.

One thing that I just found out is the Titan Pro caps are made in China and the Titan HD are made in the US. I donít know if that has anything to do with quality or not but there is definitely a difference in price.
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Old 09-08-2022, 15:30   #11
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Re: Generator Field Capacitor

the capacitor on a generator is there to dampen fast transients and help regulate the output , if you have a deficient generator or rapidly dynamic loads, you can exceed the capacitors ratings

titan pro is an established brand, I think its now made in china, and I believe its a aluminium electrolytic type, personally as I mentioned Id use metallized film types. electrolytics are much more sensitive to heat ( internal or ambient ) so if there is significant heat in their original mounting space, moving them will help
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Old 09-08-2022, 16:08   #12
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Re: Generator Field Capacitor

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Agreed! I always short them out with an insulated tool before handling. At the moment it is just zip tied to a bulkhead way out of the way but Iíll do a permanent safe mount if this corrects the issue.



One thing that I just found out is the Titan Pro caps are made in China and the Titan HD are made in the US. I donít know if that has anything to do with quality or not but there is definitely a difference in price.


Does your genset have twin capacitors? I just took a look at the Volpi/paguro in google images and the 8.5ís have 2 side by side on the control box. Iíve had a bit to do with Volpi gensets but not for AC problems, just engine issues. These engines need to be maintained carefully, clean fuel, regular oil changes and frequent inspection of the cooling water circuits. Some folks just never open up the sound shell until something goes wrong ( raw water leaks , hose and harness chafing,loose belts, mixer elbow, exhaust connection etc) and theyíre very hard to work on especially after a raw water leak in that tight sealed sound shell.
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Old 09-08-2022, 21:47   #13
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Re: Generator Field Capacitor

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Does your genset have twin capacitors? I just took a look at the Volpi/paguro in google images and the 8.5ís have 2 side by side on the control box. Iíve had a bit to do with Volpi gensets but not for AC problems, just engine issues. These engines need to be maintained carefully, clean fuel, regular oil changes and frequent inspection of the cooling water circuits. Some folks just never open up the sound shell until something goes wrong ( raw water leaks , hose and harness chafing,loose belts, mixer elbow, exhaust connection etc) and theyíre very hard to work on especially after a raw water leak in that tight sealed sound shell.
Itís a 9000 and has a single cap. Iíve though about replacing the 30uf cap with three 10uf caps in parallel to see if that helps.

This is the second engine as the first was replaced under warranty after 221 hours. We maintain it the best we can with frequent inspections and annual oil changes (we do maybe 100 hours a year).

Weíre on our third temp sensor and second water pump already.
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Old 09-08-2022, 22:25   #14
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Re: Generator Field Capacitor

Well youíre not alone with the issues that the little LDW experiences. Iím yet to see one of the common rail versions but I believe kohler has em in their newer gensets
The basic engine is solid, pistons,
block , crank all seem to last but Lombardini dropped the ball with the fuel system, hard to service and adjust and depressingly difficult finding a tech who has the tools and knowhow to get smooth power output.
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Old 10-08-2022, 06:55   #15
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Re: Generator Field Capacitor

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Well youíre not alone with the issues that the little LDW experiences. Iím yet to see one of the common rail versions but I believe kohler has em in their newer gensets
The basic engine is solid, pistons,
block , crank all seem to last but Lombardini dropped the ball with the fuel system, hard to service and adjust and depressingly difficult finding a tech who has the tools and knowhow to get smooth power output.
Initially, we had a heck of a time getting a steady RPM. It surged like heck which, obviously, itís really bad for maintaining 60 hz.

We ended up installing a Facet Dura-Lift fuel pump that is way way overkill but it solved the issue.
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