Generating trouble with Stray Current

[dmorris800]

So again, I’m not really a marine guy specifically, and I’ve only ever touched one Westerbeke for a friend, and that was just for a pump

I can tell you for certain that that capacitors don’t like heat, and all of the capacitor regulated units that I tend to down here in Florida seem to eat them much faster than the ones I dealt with in New Jersey.

If you can find American made capacitors, you’ll be better off than the cheap Chinese units but if you are using OEM components, that’s probably as good as it’s going to get.

What kind of load are you running on it? It may be worth ohming out the windings to see if something is on the way out. Do you have a service manual for it?

Thanks for the advice

 

[OllieC]

Possibly another useful data point (I hope it's useful); I wired a breakout panel into our home that allowed the powering of the 2HP well, 2 refrigerators, pellet stove, recirc fan in the central air system (no a/c), and a few lights. That way, we could keep food cold, heat in the house, and water for the roof sprinklers in case of fire. Yes, we were out in the sticks with minimal hope of fire protection. This was run with a 4kW gas generator. I did have the water heater wired in, but with the understanding that the 4kW couldn't run everything at the same time, so we'd have to manually toggle between the heavy consumers if it ever came down to it. Fortunately, it never did.

I did wire something similar, to a Reliance Controls switch, which I currently have installed. No pumps though. For that I’d need 4 more positions, new cable and a 50amp outlet box. I figured it would be cheaper to run an interlock instead so I could run the pumps.

 

[ttmott]

Seems there are a couple of considerations missing in sizing and cost for a home backup generator.

When sizing a generator's capability there is the running loads but more importantly are the inrush loads. Inrush loads are those currents the generator must provide for starting of inductive devices (motors, pumps, compressors, etc). One may go around and sum up the running loads but find after buying that generator that significant voltage drops or even stopping the generator are occurring. More importantly is the damage to equipment and electronics around the home when subjected to significant voltage sags.

Splitting up house circuits for dedication to a generator. These are typically known as critical circuits that you need/desire to have a backup power source for. Typically to do this a separate circuit breaker panel needs to be installed and those critical circuits are moved from the utility dedicated panel to the utility/generator panel.
I'd say in most cases the cost to have a dedicated critical circuit panel is higher than simply installing a whole home genset. Then there is the case to interconnect a portable generator into the home's electrical and manually shed circuits down to a load that generator can manage. Unfortunately, this requires a skill level to implement (implement to operate) that most in a household do not have. Then, finally, there are hybrid systems that automatically shed loads at the load end item when the utility drops and a genset or battery bank automatically transfers into the system to power the critical circuits. I looked into this as I have a power hungry home and found there are some pretty sophisticated systems out there. Take a look at what Generac has for shedding loads - pretty cool stuff. But, what I found is it was significantly more costly to shed loads automatically than upsize the genset. To seamlessly operate my home I needed 25KW so I ended up installing a 30KW generator with a 200 Amp automatic transfer switch.

I think the main thing to consider when looking at a backup power system is to ask the question - how do I want my home to behave if no one is there and the utility drops off line?

 

[Stray Current]

Seems there are a couple of considerations missing in sizing and cost for a home backup generator.

When sizing a generator's capability there is the running loads but more importantly are the inrush loads. Inrush loads are those currents the generator must provide for starting of inductive devices (motors, pumps, compressors, etc). One may go around and sum up the running loads but find after buying that generator that significant voltage drops or even stopping the generator are occurring. More importantly is the damage to equipment and electronics around the home when subjected to significant voltage sags.

Splitting up house circuits for dedication to a generator. These are typically known as critical circuits that you need/desire to have a backup power source for. Typically to do this a separate circuit breaker panel needs to be installed and those critical circuits are moved from the utility dedicated panel to the utility/generator panel.
I'd say in most cases the cost to have a dedicated critical circuit panel is higher than simply installing a whole home genset. Then there is the case to interconnect a portable generator into the home's electrical and manually shed circuits down to a load that generator can manage. Unfortunately, this requires a skill level to implement (implement to operate) that most in a household do not have. Then, finally, there are hybrid systems that automatically shed loads at the load when the utility drops and a genset or battery bank automatically transfers into the system to power the critical circuits. I looked into this as I have a power hungry home and found there are some pretty sophisticated systems out there. Take a look at what Generac has for shedding loads - pretty cool stuff. But, what I found is it was significantly more costly to shed loads automatically than upsize the genset. To seamlessly operate my home I needed 25KW so I ended up installing a 30KW generator with a 200 Amp automatic transfer switch.

I think the main thing to consider when looking at a backup power system is to ask the question - how do I want my home to behave if no one is there and the utility drops off line?

I’m glad to see you post in here. I’ve learned quite a bit from reading your posts on marine electrical and electronics systems.

These are all excellent points, and issues with sizing is something I run into all the time. I can’t tell you how many burned up rotors and stators in Generac 22 and 24 kW units I found after Ian. Most of the ones that quit did so within 8 hours of the outage. “But kleetus the installer said it’s a whole house generator” was the answer from every homeowner who left their Tesla plugged in, pool heat pump running, and AC cranked. I find it all the time, houses that calculate out to 35 or 40 kW with a 22 and zero load management.

I’ll be the first to admit I haven’t dusted off the the mathematical formulas for power factor and skVA in a very long time. Probably not since apprentice class honestly. I would probably have to go back and re-learn how to do some of those calculations. But I use an app or a spreadsheet template that’s exceptionally accurate, and somewhat conservative. I generally don’t have many issues with starting current in homes. Generally the ac unit or pool heat pump is the biggest surge load and the residential sized units are no issue for the new standby units. The Kohler 20 and 26 are little monsters with their powerboost technology.


You are absolutely correct about the cost to rearrange everything to a generator specific panel. It is generally far more expensive than 1 to 3 transfer switches installed at the service entrance with some load management. Sometimes it’s not possible to get all the critical loads without doing major construction if they have sub panels in different wings. I ran into that a lot at the higher end shore homes in New Jersey and I run into it a lot here in Naples. Load management systems are one of the things I do pretty well. I can setup a smaller unit that uses less fuel with delays to stagger start times and sheds unnecessary devices.

I like the Generac load management in theory, but it leaves a bit to be desired in actual practice. I am constantly going and replacing burned up boards and contactors when they fail. Not the most heavy duty components. The other thing I don’t like about them is it depends on frequency droop. It does this two ways. First, if you really overload the generator, the frequency will drop on its own. The other way is the controller uses a current transformer to read the current the generator is producing. At a certain level, the computer will actually droop the frequency to signal the remote modules to shed.

Kohler and Cummins load management is hardwired and originates in the generator controller. The nice thing about that is it uses real time voltage, frequency amperage, and to a somewhat lesser extent ambient temperature for its logic. You get a lot less droop with a Kohler Cummins unit. In the residential air cooled line, nobody is tighter than Kohler for voltage regulation and frequency governance.

I think you did the right thing by stepping up to a 30. That’s always the best option if possible. The larger alternators generally provide cleaner power and have less issues with lower power factor loads. Better yet even if you wound up with an 1800 RPM liquid cooled unit. Sometimes the small 25 and 30 liquid cooled are 3600 RPM “screamers” . I’m not a fan. There is a little bit of a trade off with small 1800 RPM units as you sacrifice a little of the starting capacity against the similarly sized air cooled at 3600. The other consideration, before deciding to step up is fuel. If you have a natural gas service, it doesn’t really matter. But if you’re on LP then sometimes it is beneficial to have a smaller unit with more management.

Another nice thing about the smaller liquid cooled units is they are generally brushless. Kohler and Cummins both are brushless. Generac still maintains brush excitation in their resi liquid cooled units. Not that there’s anything wrong with brush excitation it’s just another maintenance point that many people overlook.

There is another company that makes load management devices called PSPproducts.com They really are top notch both in quality and customer service.

Another trick I use for air-conditioning units as I install an Eltwin-hyper sure-start. They drastically reduce the inrush current by program starting the compressor. That is what I used to be able to run my 3 ton on my 5500 portable. As an added bonus, they protect your standard scroll compressor from reversion in momentary blips and outages.

https://eltwin-hyper.com/

 

[ttmott]

I’m glad to see you post in here. I’ve learned quite a bit from reading your posts on marine electrical and electronics systems.

These are all excellent points, and issues with sizing is something I run into all the time. I can’t tell you how many burned up rotors and stators in Generac 22 and 24 kW units I found after Ian. Most of the ones that quit did so within 8 hours of the outage. “But kleetus the installer said it’s a whole house generator” was the answer from every homeowner who left their Tesla plugged in, pool heat pump running, and AC cranked. I find it all the time, houses that calculate out to 35 or 40 kW with a 22 and zero load management.
View attachment 151393


I’ll be the first to admit I haven’t dusted off the the mathematical formulas for power factor and skVA in a very long time. Probably not since apprentice class honestly. I would probably have to go back and re-learn how to do some of those calculations. But I use an app or a spreadsheet template that’s exceptionally accurate, and somewhat conservative. I generally don’t have many issues with starting current in homes. Generally the ac unit or pool heat pump is the biggest surge load and the residential sized units are no issue for the new standby units. The Kohler 20 and 26 are little monsters with their powerboost technology.


You are absolutely correct about the cost to rearrange everything to a generator specific panel. It is generally far more expensive than 1 to 3 transfer switches installed at the service entrance with some load management. Sometimes it’s not possible to get all the critical loads without doing major construction if they have sub panels in different wings. I ran into that a lot at the higher end shore homes in New Jersey and I run into it a lot here in Naples. Load management systems are one of the things I do pretty well. I can setup a smaller unit that uses less fuel with delays to stagger start times and sheds unnecessary devices.

I like the Generac load management in theory, but it leaves a bit to be desired in actual practice. I am constantly going and replacing burned up boards and contactors when they fail. Not the most heavy duty components. The other thing I don’t like about them is it depends on frequency droop. It does this two ways. First, if you really overload the generator, the frequency will drop on its own. The other way is the controller uses a current transformer to read the current the generator is producing. At a certain level, the computer will actually droop the frequency to signal the remote modules to shed.

Kohler and Cummins load management is hardwired and originates in the generator controller. The nice thing about that is it uses real time voltage, frequency amperage, and to a somewhat lesser extent ambient temperature for its logic. You get a lot less droop with a Kohler Cummins unit. In the residential air cooled line, nobody is tighter than Kohler for voltage regulation and frequency governance.

I think you did the right thing by stepping up to a 30. That’s always the best option if possible. The larger alternators generally provide cleaner power and have less issues with lower power factor loads. Better yet even if you wound up with an 1800 RPM liquid cooled unit. Sometimes the small 25 and 30 liquid cooled are 3600 RPM “screamers” . I’m not a fan. There is a little bit of a trade off with small 1800 RPM units as you sacrifice a little of the starting capacity against the similarly sized air cooled at 3600. The other consideration, before deciding to step up is fuel. If you have a natural gas service, it doesn’t really matter. But if you’re on LP then sometimes it is beneficial to have a smaller unit with more management.

Another nice thing about the smaller liquid cooled units is they are generally brushless. Kohler and Cummins both are brushless. Generac still maintains brush excitation in their resi liquid cooled units. Not that there’s anything wrong with brush excitation it’s just another maintenance point that many people overlook.

There is another company that makes load management devices called PSPproducts.com They really are top notch both in quality and customer service.

Another trick I use for air-conditioning units as I install an Eltwin-hyper sure-start. They drastically reduce the inrush current by program starting the compressor. That is what I used to be able to run my 3 ton on my 5500 portable. As an added bonus, they protect your standard scroll compressor from reversion in momentary blips and outages.

https://eltwin-hyper.com/

I installed a 30kw Protector Series Generac Diesel genset with large integrated fuel tank; 8 days of run time at 50% average load. It has a 4-cylinder 1800 RPM turbocharged Perkins. It's a beast.
I also have 12KW of solar on the house with Generac Pwrcell inverters. The entire system uses a data buss that works on the DC and AC power conductors called reBuss. So they may have moved away from frequency drooping in their later products.

 

[Stray Current]

I installed a 30kw Protector Series Generac Diesel genset with large integrated fuel tank; 8 days of run time at 50% average load. It has a 4-cylinder 1800 RPM turbocharged Perkins. It's a beast.
I also have 12KW of solar on the house with Generac Pwrcell inverters. The entire system uses a data buss that works on the DC and AC power conductors called reBuss. So they may have moved away from frequency drooping in their later products.
View attachment 151397

Man, you’re gonna give me a heart attack with those clearances! Is there a vented soffit?

The protector diesel unit as a much higher quality product than the standard residential line though. I think that may also be brushless. Either way it’s going to have a much heavier duty alternator. I don’t do too many diesels

I have absolutely zero experience with Generac solar systems. Their load management system on the inverters is probably considerably different than the gensets. They are definitely still using frequency droop there

The powercell and Kohler offering are something my company is looking into offering. I haven’t really done anything with solar other than grid tied interactive systems. We always tried to stay away from it because the generators were more lucrative back in Jersey

 

[ttmott]

Man, you’re gonna give me a heart attack with those clearances! Is there a vented soffit?

The protector diesel unit as a much higher quality product than the standard residential line though. I think that may also be brushless. Either way it’s going to have a much heavier duty alternator. I don’t do too many diesels

I have absolutely zero experience with Generac solar systems. Their load management system on the inverters is probably considerably different than the gensets. They are definitely still using frequency droop there

The powercell and Kohler offering are something my company is looking into offering. I haven’t really done anything with solar other than grid tied interactive systems. We always tried to stay away from it because the generators were more lucrative back in Jersey

It's tight but meets code. The soffit vents are not in this area. Plus that's all Hardie board.

I really did a lot research into solar technology. First you cannot do a grid tied solar system unless the system meets specific UL requirements for lineman and fire safety. This alone narrows down the field to a handful of inverters and systems. Victron for example who I'm a big fan of does not have the certifications. So that comes down to two categories mixed component and integrated. Integrated comes down to two brands Tesla and Generac. The Generac system provided the best expandability with a host of voltaic cell manufacturers. We installed REC panels.

Now, if I did all of this again I'd still go Generac but with a twist. Now Generac makes a small DC genset specifically for charging their battery banks. So lets say nominally the solar system with a reasonable sized battery bank day to day the system needs no grid (I haven't had a power bill since Jan when we activated it). Now lets say the solar input is compromised (clouds, storms etc) and the battery bank is low on charge - that little DC genset cycles on and off to charge the banks. It is a nicely designed system that essentially removes the need to be on the grid.

 

[Stray Current]

I really did a lot research into solar technology. First you cannot do a grid tied solar system unless the system meets specific UL requirements for lineman and fire safety. This alone narrows down the field to a handful of inverters and systems. Victron for example who I'm a big fan of does not have the certifications. So that comes down to two categories mixed component and integrated. Integrated comes down to two brands Tesla and Generac. The Generac system provided the best expandability with a host of voltaic cell manufacturers. We installed REC panels.

Now, if I did all of this again I'd still go Generac but with a twist. Now Generac makes a small DC genset specifically for charging their battery banks. So lets say nominally the solar system with a reasonable sized battery bank day to day the system needs no grid (I haven't had a power bill since Jan when we activated it). Now lets say the solar input is compromised (clouds, storms etc) and the battery bank is low on charge - that little DC genset cycles on and off to charge the banks. It is a nicely designed system that essentially removes the need to be on the grid.

I haven’t touched a gridtied system since probably 2017 or 2018 and I’m sure things have changed a lot since then. At the time it was mostly Enphase micro inverters that daisy chain together on one of their special cables before it hits the combiner and goes down to the metering equipment, and then either line tapped ahead of the MCB or became a backfeed breaker, depending on whether there was a generator involved or not.

I haven’t read anything about Generac’s new DC generator but a long time ago they had an Ecogen air cooled unit that was set up for that specific purpose. One of the cool features about that was it had a four or 5 quart additional remote oil reservoir. It also had a 2000 hour warranty for off grid use. There was a variable speed Ecogen, but it was very problematic and it got dropped in favor of the single speed unit.

Kohler also makes a 48 V DC generator for off grid solar back up applications. I do the maintenance on one of those out on Cayo Costa island for a customer with a massive conventional deep cycle battery bank for their off grid system. I think they have 12 kW worth of panels.

Integrating their solar system with their generators is going to be a game changer for a lot of things. I’ve often said a large battery bank with a high starting capacity on solar with a very small generator to supplement was going to take off once the battery technology gets there

 

[ttmott]

I haven’t touched a gridtied system since probably 2017 or 2018 and I’m sure things have changed a lot since then. At the time it was mostly Enphase micro inverters that daisy chain together on one of their special cables before it hits the combiner and goes down to the metering equipment, and then either line tapped ahead of the MCB or became a backfeed breaker, depending on whether there was a generator involved or not.

I haven’t read anything about Generac’s new DC generator but a long time ago they had an Ecogen air cooled unit that was set up for that specific purpose. One of the cool features about that was it had a four or 5 quart additional remote oil reservoir. It also had a 2000 hour warranty for off grid use. There was a variable speed Ecogen, but it was very problematic and it got dropped in favor of the single speed unit.

Kohler also makes a 48 V DC generator for off grid solar back up applications. I do the maintenance on one of those out on Cayo Costa island for a customer with a massive conventional deep cycle battery bank for their off grid system. I think they have 12 kW worth of panels.

Integrating their solar system with their generators is going to be a game changer for a lot of things. I’ve often said a large battery bank with a high starting capacity on solar with a very small generator to supplement was going to take off once the battery technology gets there

https://www.generac.com/generaccorp.../pwrcell/pwrgenerator-spec-sheet.pdf?ext=.pdf
The main technical reason I went with Generac is because the system is DC coupled which sets the stage for expandability.

 

[SeasNT]

Fascinating conversation, you folks are far above my pay grade. Thanks for sharing your thoughts on topics that I think about. TTMOTT, you mentioned your residential diesel genset. How do you keep the fuel from getting stale? I have a TV helicopter pilot friend that talked the chief engineer into storing 2000 gals of Jet A instead of diesel for the station backup genset. They laid in a fuel pump at the adjacent helipad. They could fuel the turbine chopper much cheaper than the local airport. He said the Jet A had a much longer shelf life, but cost more too.

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[ttmott]

Fascinating conversation, you folks are far above my pay grade. Thanks for sharing your thoughts on topics that I think about. TTMOTT, you mentioned your residential diesel genset. How do you keep the fuel from getting stale? I have a TV helicopter pilot friend that talked the chief engineer into storing 2000 gals of Jet A instead of diesel for the station backup genset. They laid in a fuel pump at the adjacent helipad. They could fuel the turbine chopper much cheaper than the local airport. He said the Jet A had a much longer shelf life, but cost more too.

​

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Jet A is essentially refined kerosene with additives for use at altitude and low temperatures right?
RP1 is the same thing but for rockets.
Can you use kerosene for a compression ignition engine??

I use the same treatment system on the generator as I use on the boat. Algae is the big worry. The generator starts and runs for twenty minutes every week.

 

[SeasNT]

They claim it worked using Jet A, but EPA might frown on its use these days.

 

[highslice]

Jet A is essentially refined kerosene with additives for use at altitude and low temperatures right?
RP1 is the same thing but for rockets.
Can you use kerosene for a compression ignition engine??

I use the same treatment system on the generator as I use on the boat. Algae is the big worry. The generator starts and runs for twenty minutes every week.

Isn't a turbine just a horizontal compression ignition engine?

 

[Nater Potater]

Isn't a turbine just a horizontal compression ignition engine?

Continuous cycle engine.

 

[Nater Potater]

They claim it worked using Jet A, but EPA might frown on its use these days.

It'll run, but, being so heavily refined, kerosene has virtually no lubricating properties. You stand a pretty good chance of causing irreparable harm to injectors and/or injector pump on kerosene alone.

 

[ttmott]

@Stray Current Pic of the back end during install; there are brushes -

 

[Stray Current]

Pic of the back end during install; there is brushes -
View attachment 151507

Grab an extra set of those and commutator stone. One of the most common problems I was seeing after Ian with brushed excitation units was brush failure, and slip ring pitting after contamination with driven salt spray.

You can also use 2000 grit wet or dry paper if you’re just polishing them up a little bit and they’re not too bad. I’ve gone as aggressive as 800 grit to get nasty ones cleaned up.

I’m kind of surprised to see brushes on a diesel, but that may be considered a commercial unit and not an industrial.

Another thing that I do for my coastal customers is a spray the units down inside with salt terminator. Anytime the temperatures change in the unit to get condensation, the chemical reactivates to neutralize any salt that may have gotten in there from the air. It helped a lot at the shore homes in New Jersey.

 

[Stray Current]

This thing still runs after some repairs due to the salt spray, but the salt spray really tore it up. I kind of advised the customer he may want to consider a replacement, but he decided to roll the dice and replace a half dozen components.

 

[Stray Current]

On the flipside, I had a half dozen Kohler’s that went more than 2/3 of the way underwater and we were able to get them back up and running temporarily. The machines were goners at that point, but they all ran for a couple extra days until utility power came back.

 

[Stray Current]

Contrary to popular belief, salt is the Devil, and not fooseball. I’m gonna have to transfer some pictures from my work phone and upload them. The other big thing that destroys generators is mineral rich irrigation water.

I think a bunch of guys on a boating forum understand how much damage electrolytic action from dissimilar metals can do