Generator Phase?

[jok]

I have a Yanmar/Martin generator feeding two Trace SW4024 inverters. I have a 240 volt dryer and cooktop. The original wiring from the generator went to a transformer and then to the inverters (bus was originally a mobile recording studio). Other bus-nuts and myself did not understand the need for the transformer. We bypassed the transformer and everything seemed okay, but we did not test 240 volt items using generator. On a recent trip we used the dryer with no problem when attached to the shoreline. When trying to use the dryer with the generator running, the dryer ran, but did not heat up. With the generator off the dryer worked properly from the inverters.

I am over my head with most electrical things beyond simple household wiring. I think I recall something about being "in phase", or "out of phase". My question (finally) is, do the two "hot" lines from the generator need to be in phase, or out of phase. And if "out of phase", how much out (180?). What is  the process of changing the phase. I am comfortable wiring transformers needed for printing equipment, but I am not familiar with generators.

Thanks for any help you can give me,

John

[jok]

The original wiring from the generator/transformer actually only went to one inverter, so "phase" was not an issue, as I understand it. When I reconverted the bus I installed the two SW40124 inverters. I can reinstall the transformer, but I would like to eliminate any unneeded weight if possible.

Thanks again,

John

[Sean]

John,

This sort of thing is very difficult to diagnose via text like this.

What is the make and model of your generator?  Perhaps it is a 120-volt-only unit.

If the generator is capable of 240, it is usually a simple wiring change in a junction box near the alternator to re-strap for 240.  But you really need to know what you are doing, or you can fry things.

BTW, "phase" does not really apply here.  240/120 volt, residential-type power is all single phase.  In a grid application, the transformer secondary is center-tapped and the neutral and ground are connected to this tap, which has the effect of making each 120-volt "leg" appear to be 180-degrees phase-shifted from the other.  The reality is they are both part of the same waveform.  In a generator application, you are simply choosing a different set of taps on the stator -- again, it is a single waveform.

It is possible that whatever transformer you removed was there to provide 240 from 120, in the case of a 120-only generator with some 240-volt load.  Again, make and model of transformer will help us.

-Sean
http://ourodyssey.blogspot.com

[jok]

Thanks Sean,

I will check to see if I can find more information in the morning. I believe that the transformer does go from 120 volt to 240 volt. So, maybe the generator is a 120 volt only generator, or at least wired that way. The name plate is missing on the generator but John Palmer told me it is around 17,500 watts based on the breaker (I believe it is a 100 amp breaker) and that it is a "martin" generator. It has a four cylinder Yanmar diesel engine.

Can you also enlighten me on battery charging. I think I had read somewhere that you should not use a belt driven generator (12v) to charge you house batteries when going down the road. What problems will this cause.

I just installed 4 new Lifeline AGM 8D batteries and I read on another post that you said to equalize the batteries once a month. Can I use the equalize feature of the SW4024 inverter? Can I equalize all 4 batteries at the same time (they are in series and in parallel), and, if so do I need to disconnect the inverter from the breaker box during equalizing. The inverters are set at the default settings for these batteries. Is that the best thing for a long battery life, or should I modify the settings.

Sorry for all the different questions, but I see from your posts that you have extensive knowledge on these items and I can't resist picking your brain.

Thanks,
John

[Sean]

I will check to see if I can find more information in the morning. I believe that the transformer does go from 120 volt to 240 volt. So, maybe the generator is a 120 volt only generator, or at least wired that way. The name plate is missing on the generator but John Palmer told me it is around 17,500 watts based on the breaker (I believe it is a 100 amp breaker) and that it is a "martin" generator. It has a four cylinder Yanmar diesel engine.

Martin made/makes several different models.  Without the number, it's hard to know, but they are still around and you can call their customer support department -- they may be able to identify the model and send you a wiring diagram.

With a four-cylinder Yanmar I would think it is definitely in the 15K range.  However, a 100-amp breaker would either mean 12K (standby) for a 120-volt unit, or over 20K (standby) for a 240-volt unit.  None of which means anything unless it is part of the original generator supplied by Martin -- many coach installations use breakers and enclosures furnished by the coach builder.

If the breaker is single-pole, though, that would pretty much guarantee that the unit is currently strapped for 120 volts.  The good news is that most Martins can be restrapped for 240.

Can you also enlighten me on battery charging. I think I had read somewhere that you should not use a belt driven generator (12v) to charge you house batteries when going down the road. What problems will this cause.

An alternator being belt-driven is not a problem in and of itself.  However, you need to make sure the belt drive is matched to the charging output of the alternator, as most large house banks will cause the alternator to run at maximum capacity for long periods when they are depleted and absorbing lots of charge.  A large 12-volt Delco 50DN, for example, can charge at 4,200watts.  That's about six horsepower, and your belt drive system will need to be able to transmit that six horsepower continuously.  Also, of course, the alternator itself will need to be able to handle the load -- some accessory alternators are not rated for full output continuously.

I do wonder why you mention 12 volts, though, since the SW4024 implies that you actually have a 24-volt house system, and I presume also that your Prevost has a 24-volt alternator.

I just installed 4 new Lifeline AGM 8D batteries and I read on another post that you said to equalize the batteries once a month.

Actually, I said that in a discussion related to flooded batteries, which do need periodic equalization.  AGM batteries generally should never be equalized under normal circumstances.  That being said, certain over-depletion conditions can benefit from equalization at settings specified by the battery manufacturer -- consult with Lifeline before doing this if needed.  Again, you should never need to in normal use.

Can I use the equalize feature of the SW4024 inverter? Can I equalize all 4 batteries at the same time (they are in series and in parallel), and, if so do I need to disconnect the inverter from the breaker box during equalizing.

If you ever needed to equalize, yes, the SW4024's equalization feature can be used.  You would generally equalize the entire bank at once.  There is no need to disconnect the output breakers unless your input source is too small to run the charger and the output loads at once.  The SW4024 charger uses a maximum of 33amps at 120VAC.

The inverters are set at the default settings for these batteries. Is that the best thing for a long battery life, or should I modify the settings.

The default settings are almost never the best ones for optimum battery life or performance.  They are generally usable as-is, but tuning the system based on your actual battery capacity and anticipated usage is always better.

The correct voltage settings for the bulk and float stages of the charger should be listed on the specification sheet or owner's manual for the Lifeline batteries.  I don't have it handy, but I am sure it is also available on their web site.  Use the manufacturer's recommendations for these settings if different from the defaults.  Also, make sure you set the Maximum Charge Amps based on the specifications.  The formulas are in the SW4024 manual.

HTH,

-Sean
http://ourodyssey.blogspot.com

[Ncbob]

John, as I was reading your post the very first thing that came to mind was that the transformer was there only for the dryer which would require 240 VAC. Your generator, since it feeds both inverters, is probably wired straight 120VAC which is the same as you'd be able to get from a shore hookup.

My guess is that the transformer was connected in a way that it was able to convert either generator and/or shore power for the washer/dryer. And, phase doesn't enter the equation here...everything is single phase.

Heck, it must have worked for the former owner so I'd reconnect and test it.

Moral: We really need to be careful about disconnecting and connecting things we don't understand. It's possible that you won't see an immediate change in anything because some of our systems can be pretty complex. Pray that it isn't one of your grandchildren who discovers your error.

Bob

[DrivingMissLazy]

Other bus-nuts and myself did not understand the need for the transformer. We bypassed the transformer and everything seemed okay,
John

Don't know who the other busnuts are, but I would strongly suggest you find some other nuts that understand electrical systems. LOL

Richard

[TomC]

Just for comparison of another type of system-I have a 10kw Powertech generator that is wired straight 120vac.  This assures that the loads on the generator will always be balanced between the two different windings.  The disadvantage to this is that I can only use one leg of the 50 amp land line-which for me has not been a handicap-even though my bus, except for the stove and furnace, is all electric.  I just have to be a bit careful of what I use when.  50 amps will easily run two roof top A/C's (can sometimes do it on 30amps).  I just alternate the 2 water heaters.  My two water heaters are plumbed one into the next so I first heat the final one, then heat the first one and leave it on since it flows into the final water heater.  If I do another RV, I'll wire it the same again.  Good Luck, TomC

[jok]

Thanks for the information and feedback. I have a great respect for electricity, and anything else I don't understand.  My electrical knowledge is limited, so I try to get help from others that know the field. Even then, I want to make sure the information is correct. That is one of the great things about the people on this board. There is a wealth of knowledge from people willing to share that knowledge. I would be up a creek without your help.

I think a little history of my conversion might help. It was originally converted by American Coach in Allen, Michigan in 1990 as a mobile recording studio. The recording company would drive to concerts and tap into the sound system. Later they would use the gathered music to release a "live album". I basically removed the original conversion down to the interior plywood. I used the original dash, drivers seat, water tanks, generator and 12 volt alternator.

The original conversion had a 12 volt house battery bank that supplied one 120 volt inverter. The battery bank was charged by the diesel generator and the 12 volt belt drive Motorola 10-255 (130 amps?) alternator. Other than charging the batteries, I believe the generator was mostly used for the 6 air conditioners, a kitchenette and lighting. There was a large spool (100+ feet) of wire that was used for shore power. It had 4 individual plugs and I assume it was used to power the sound equipment. Nothing in the original conversion was 240 volt. I added the dryer and cooktop for our conversion.

Sean, you are correct about my house battery bank being 24 volt. I attached the original 12 volt line from the alternator to a 12 volt post of the 24 volt house battery bank. Is this a bad idea? I do not run the roof air unless I am running the generator,  I would love to. I am thinking of adding a larger belt drive alternator to supply my house batteries. Should I go to 24 volts? What is the minimum size I should use?

The actual bus is 24 volts. It came with a 24 volt Delco-Remy 1117069 (75 amps?) for the bus system. But the bus also came from Prevost with the belt drive 12 volt alternator, with is tapped into the bus electrical system. The original converter ran a line to the 12 volt house battery bank.

The generator has a 70 amp breaker (not 100 as I thought, oops). It is a Square D QOU270, 2 pole 120/240 breaker. It has four wires. A ground, a neutral and two hots, one to each SW4024. Does this sound like it can be rewired to fix my problem? I will try to get more information on which model it is.

Thanks for the battery equalizing and maintenance information. I am getting enough electrical knowledge to be dangerous, instead of just oblivious.

John

[Sean]

The original conversion had a 12 volt house battery bank that supplied one 120 volt inverter. The battery bank was charged by the diesel generator and the 12 volt belt drive Motorola 10-255 (130 amps?) alternator....

Since you have chosen to run a 24-volt house bank, and the bus is also 24 volts, all the above 12-volt equipment is now, essentially, irrelevant.  Unless you want to have two different house systems, one for 24-volt (including your inverters) and a separate one for any 12-volt loads, you can ditch the 12-volt alternator.  The usual way to drive 12-volt loads from a 24-volt system is to use the center tap of the battery, and then install an "equalizer" to ensure that the upper and lower halves of the battery stay at about the same voltage and depletion level.

Sean, you are correct about my house battery bank being 24 volt. I attached the original 12 volt line from the alternator to a 12 volt post of the 24 volt house battery bank. Is this a bad idea?

Yes, this is a very, very bad idea.  If you have an equalizer in the picture, as mentioned above, and it is the bi-directional type, and it is of a large enough rating, then it is possible that the equalizer might be taking some of that charge current at the 12-volt terminal and supplying it to the 24-volt terminal.  But those are three really big "ifs."  Unless you really know what you are doing, and have the instrumentation to monitor this situation carefully, I would advise strongly against doing this.  You will end up frying the lower batteries and over-depleting the upper ones, ruining the whole bank in short order.

I do not run the roof air unless I am running the generator,  I would love to. I am thinking of adding a larger belt drive alternator to supply my house batteries. Should I go to 24 volts? What is the minimum size I should use?

The actual bus is 24 volts. It came with a 24 volt Delco-Remy 1117069 (75 amps?) for the bus system. But the bus also came from Prevost with the belt drive 12 volt alternator, with is tapped into the bus electrical system. The original converter ran a line to the 12 volt house battery bank.

I don't understand the "tapped into the bus electrical system" comment.  My guess is that the bus electrical system is strictly 24 volts, and the 12-volt alternator was only used to charge house batteries.  This unusual alternator arrangement would have been special order for American Coach.

I would ditch the 12-volt, and trade the 25SI unit you have now on the 24 volt side for a 50DN if at all possible, which could easily serve both house and chassis.  Another option would be to keep the 25SI right where it is, and change out the 120 volt Motorola for a suitable 24-volt model.  The problem you will run into is getting high enough ratings with belt drive and air cooling.  The big 50DNs are available gear-driven and oil-cooled, which is how they manage to crank 4.2-6.5kW out of them.

The generator has a 70 amp breaker (not 100 as I thought, oops). It is a Square D QOU270, 2 pole 120/240 breaker. It has four wires. A ground, a neutral and two hots, one to each SW4024. Does this sound like it can be rewired to fix my problem? I will try to get more information on which model it is.

Where the two hots go is less relevant than where they come from.  Again, this is hard to diagnose by remote control -- you're going to have to open up the generator and follow wires.  But first, I'd turn the breaker "off", start the genny, and then take a meter to the input side of the breakers, and see if you read 240 between them, or zero.

-Sean
http://ourodyssey.blogspot.com

[Chris 85 RTS]

The disadvantage to this is that I can only use one leg of the 50 amp land line

Not sure I understand why this is the case.  I also have a genset wired for 120V only operation, but my shore cord and breaker panel are setup for 240V (or two legs of 120V).  The disadvantage is that I can not run any true 240V loads, but I don't have any anyway.  My genset supplies 120V to both legs of the shore cord.  Oh, maybe that is the difference, I use my shore cord to switch between pole power and genset power.  I still think that if the tie point between the two legs is in the genset, then you can use both legs on the shore cord, even with a transfer switch.

[JackConrad]

We have our genset set up 120 only. our shoreline is 50 amp 240. Our transfer switch is a 50 amp Iota switch. The inputs to the transfer switch are a ground (green), neutral (white), hot (red) and hot (black) from the shoreline and the genset. The 4 wires from the shoreline were connected to the 4 terminals for shoreline input. Since the generator only has 3 wires ground (green), neutral (white), hot (black), these were connected to the appropriate generator input terminals of the transfer switch. We then added a jumper between the generator input red & back terminals. The generator now powers all circuits (up to the capcity of the generator).

[jok]

I am grateful to the bus-nuts who originally suggested the removal of the transformer. I think (hopefully) it will help me eliminate un-need parts that take up space, add extra weight and can fail (KISS). I just need to be better at giving all the details involved. I don't think I mentioned the 240 volt dryer and cooktop, so 240 volt vs 120 volt seemed irrelevant. Now I know better, and I will try to give better information to those helping me.

Sean,

I finally got around to see what the voltage coming out of the generator was. Each leg is 120 volts. Between the two legs is zero volts. Not surprising, given what you have pointed out. How involved is having it "restrapped for 240"?

Going to a large belt drive 24 volt alternator sounds like a great way to go. I do have an equalizer for the house battery bank, but I don't know if it is the bi-directional type, or it is of a large enough rating. I like the idea of going to the 24 volts feeding the battery bank. I will start checking into getting one.

I am looking forward to running the generator less.

Thanks,
John

[Sean]

...
I finally got around to see what the voltage coming out of the generator was. Each leg is 120 volts. Between the two legs is zero volts. Not surprising, given what you have pointed out. How involved is having it "restrapped for 240"?

John,

This is a very manufacturer-specific change.  Rather than guess at it, I would give Martin a call at their customer service department at 866-868-9911.  Be ready with the model number and any other information you can find.  They will be able to tell you where the jumpers are and what you need to do to change over to 240, or at least send you a schematic.

Here is their web site:
http://www.martindiesel.com/Products/products_generators.htm

HTH,

-Sean
http://ourodyssey.blogspot.com

[jok]

Sean,

Thanks for all the great information. I have contacted Martin through their website and hope to get a response soon. The electrical system has been one of the most worrisome parts of the conversion for me. I think I have my inverters set up correctly for my batteries now and will work on replacing my alternator. Hopefully I will have my generator "restrapped" soon. Thanks to you, and everyone else, for all your patience and help.

John