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Old 08-23-2011, 07:05 PM   #21
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Looks like I have avoided a fire

Quote:
Delfin wrote:

The main problem is that the 230/240V motor run on 208V will run a lot hotter and not last as long.* Most trawlers run by folks on this forum will not have 230V motors in any case, and trying to run a 115V motor on 104V will also produce similarly unsatisfactory results.

Since 415V 3 phase does not produce 208V from any leg, I'm not sure why the marina says that is what they are getting from their 415V supply.*
There is no 415 volt supply in the US, we are talking about a US marina. They obviously don't know what their supply voltage is.

There is no 104 volt supply either. That number appears to have come from a poster thinking that 208 volts between legs would supply half that between a leg and ground or neutral. AC electricity doesn't work that way even though the common use of 240/120 supplied by a center tap transformer seems to the unitiated that it does.

There is a big difference between resistive heating loads and motor loads. A 230 volt rated moter (which most are) will happily operate on 208 and most state that on the nameplate. All this information is readily available from manufacturers and suppliers. Repeating old wive's tales and nonsense heard on the dock only confuses people more. Look it up, read an electrical power text, look at motor ratings.


-- Edited by RickB on Tuesday 23rd of August 2011 07:10:06 PM
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Old 08-23-2011, 08:01 PM   #22
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RE: Looks like I have avoided a fire

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RickB wrote:Delfin wrote:

The main problem is that the 230/240V motor run on 208V will run a lot hotter and not last as long.* Most trawlers run by folks on this forum will not have 230V motors in any case, and trying to run a 115V motor on 104V will also produce similarly unsatisfactory results.

Since 415V 3 phase does not produce 208V from any leg, I'm not sure why the marina says that is what they are getting from their 415V supply.*
There is no 415 volt supply in the US, we are talking about a US marina. They obviously don't know what their supply voltage is.

There is no 104 volt supply either. That number appears to have come from a poster thinking that 208 volts between legs would supply half that between a leg and ground or neutral. AC electricity doesn't work that way even though the common use of 240/120 supplied by a center tap transformer seems to the unitiated that it does.

There is a big difference between resistive heating loads and motor loads. A 230 volt rated moter (which most are) will happily operate on 208 and most state that on the nameplate. All this information is readily available from manufacturers and suppliers. Repeating old wive's tales and nonsense heard on the dock only confuses people more. Look it up, read an electrical power text, look at motor ratings.

*

*The poster has his answer.* Just tell the marina that they don't know what their electrical service is.* Reference RickB, and who knows, he may be right.

230V motors will not "operate happily" at 208V.* This is not dock talk/old wive's tales*as you suggest, but simply a fact of physics.* I suggest you take your own advice and look at any motor supplier's offering, for example Grainger.* About 1/7th of their motors are dual rated for 208/230V because it is not the norm for single phase motors.* All other motors are rated at 230/240V and while they will turn at 208V or 150V, they won't last as long.* On the Grainger site, they have 54 skus for 208/230 volt single phase motors.* They have 373 skus for 230v motors that aren't deisigned to run on 208V.* To recommend that there is no material difference between these two configurations is not particularly helpful, or correct, however boldly you assert it.* Perhaps you are confusing single with 3 phase motors?* 208/230 3 phase are standard, but not present on small trawlers.

I also took your advice in looking this up in an "electrical power text".* Here is the reference I found:

Low voltage can lead to overheating, shortened life, reduced starting ability, and reduced pull-up and pullout torque. The starting torque, pull-up torque, and pullout torque of induction motors all change, based on the applied voltage squared. Thus, a 10% reduction from nameplate voltage (100% to 90%, 230V to 207V) would reduce the starting torque, pull-up torque, and pullout torque by a factor of .92.9. The resulting values would be 81% of the full voltage values. At 80% voltage, the result would be .82.8, or a value of 64% of the full voltage value. What does this translate to in real life? Well, you can now see why it's difficult to start "hard-to-start" loads if the voltage happens to be low. Similarly, the motor's pullout torque would be much lower than it would be under normal voltage conditions.

*
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Old 08-23-2011, 08:18 PM   #23
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Looks like I have avoided a fire

Yawn,

You are so predictable Delphin. You would argue that it was night at noon if I said it was daylight.

The old "wrestling with pigs" thing pretty much covers any discussion where you are involved. See you around.

*

And for those who are interested:

http://www.motorsanddrives.com/cowern/motorterms11.html


-- Edited by RickB on Tuesday 23rd of August 2011 08:24:10 PM
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Old 08-23-2011, 08:27 PM   #24
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RE: Looks like I have avoided a fire

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RickB wrote:
Yawn,

You are so predictable Delphin. You would argue that it was night at noon if I said it was daylight.

The old "wrestling with pigs" thing pretty much covers any discussion where you are involved. See you around.
*What is predictable is your mix of good advice based on wide experience and knowledge randomly conjoined with completely errant and erroneous nonsense.* The problem is that it occasionally takes an interpreter to separate the two.* Glad to be of service.

And I wouldn't agrue that night is day, but would note that there is a reason why motors to be run on 208 volts are wound for 208 voltage.*
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Old 08-23-2011, 08:30 PM   #25
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RE: Looks like I have avoided a fire

Now now....
Don't make me light YOU guys on fire!
Play nice now!
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Old 08-23-2011, 08:54 PM   #26
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Looks like I have avoided a fire

*



*

*


-- Edited by Keith on Wednesday 24th of August 2011 04:54:46 AM
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Old 08-23-2011, 09:00 PM   #27
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Looks like I have avoided a fire

Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.* http://www.ebls.org/




-- Edited by markpierce on Tuesday 23rd of August 2011 09:05:28 PM
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Old 08-23-2011, 09:13 PM   #28
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RE: Looks like I have avoided a fire

Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.

*

----------------------------------------------------------------

Only thing I know is, I have 120 volts off the dock and 120 volts out of my gen set. *So life is good!!

p.s. Nice little Island cottage, I wonder if they have 120 volts or something else?*
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Old 08-23-2011, 09:18 PM   #29
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RE: Looks like I have avoided a fire

Quote:
Edelweiss wrote:
Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.

*

----------------------------------------------------------------

Only thing I know is, I have 120 volts off the dock and 120 volts out of my gen set. *So life is good!!

p.s. Nice little Island cottage, I wonder if they have 120 volts or something else?*
*I think I see a plume of smoke coming out of the building to the right.* So I suspect they are running 240V motors on 208V.....
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Old 08-23-2011, 11:21 PM   #30
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RE: Looks like I have avoided a fire

Quote:
RickB wrote:bobc wrote:I discovered that my 30A breaker, which was the right size, had the hot lead paralleled across both breakers, rather than switching both the hot and the neutral.** In effect, I had a 60A breaker.*
You might want to review your electrical laws.
*

*With two breakers in parallel, the current is split half the current through one, half through the other (assuming equal resistance of the contacts).* This means the combination can pass a total of 60A with each breaker conducting 30A.* I think I'm on safe ground here.
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Old 08-24-2011, 02:56 AM   #31
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RE: Looks like I have avoided a fire

Well whilst us in yoorup have been asleep it seems battle commenced in the USA!*

I was at least right about one thing, the USA AC systems are very confusing!* Sorry if I opened a can of worms with my questions.

I think we will just hope that our 110V will somehow be connectible, via the cords and adapters*that came with the boat,*in our allocated slip when we get back there.* Our boat is currently out of the water in St Augustine FL patiently waiting for us to get sold up here and return...**

I asked for a 110V 50A connection if possible, the marina said:-

It'll have a 50amp 208v electric hookup, which you can split down to (2) 30amp cords.**Of course, you'll have to have a splitter.**Should a slip with (2) 30's comes open, I can simply change slips for you.

They list 110V 50A at $80/month and 208V/50A at $160/month or 110V 30A at $72 (per cord).* I'm concerned on two counts, one that we can get 110V on board but two that $80/month is a whole lot better than $160!* We know we can run almost everything*on a single 30A 110V connection, the previous owners did that but had one of the 3 aircon units off to do*it because the third would be just too much.* On that basis a 110V 50A supply would seem ideal especially as at $80 it is only a bit more than a 30A at $72/month.* Two 30As to give 60A total*however add up to $144 a whole lot more!

*
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Old 08-24-2011, 04:09 AM   #32
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RE: Looks like I have avoided a fire

Not all 120V is the same , the area under a poor voltage curve can carry 20% 35% less power .

Mostly heavily loaded induction motors have the hardest time, an air cond , not a reefer.

Folks that use inverters will see the most hassles as unless they are really expensive the wave form (power output) is usually poor.

A simple solution is to visit yard sales and purchase most any tools that have brush mounts visible on the motor.

These are called universal motors and will show AC/DC on the nomenclature plate.

Feed the 120V unit 90V , and its a 90V motor , it doesn't gobble amps the way an induction motor will.
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Old 08-24-2011, 06:39 AM   #33
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RE: Looks like I have avoided a fire

Quote:
bobc wrote:*I think I'm on safe ground here.
*Yes, you are. I reread your post and see that I mistakenly read it as meaning there was a 30A breaker on each leg. Please accept my apology.
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Old 08-24-2011, 09:07 AM   #34
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RE: Looks like I have avoided a fire

Quote:
Robin wrote:
Well whilst us in yoorup have been asleep it seems battle commenced in the USA!*

I was at least right about one thing, the USA AC systems are very confusing!* Sorry if I opened a can of worms with my questions.

I think we will just hope that our 110V will somehow be connectible, via the cords and adapters*that came with the boat,*in our allocated slip when we get back there.* Our boat is currently out of the water in St Augustine FL patiently waiting for us to get sold up here and return...**

I asked for a 110V 50A connection if possible, the marina said:-

It'll have a 50amp 208v electric hookup, which you can split down to (2) 30amp cords.**Of course, you'll have to have a splitter.**Should a slip with (2) 30's comes open, I can simply change slips for you.

They list 110V 50A at $80/month and 208V/50A at $160/month or 110V 30A at $72 (per cord).* I'm concerned on two counts, one that we can get 110V on board but two that $80/month is a whole lot better than $160!* We know we can run almost everything*on a single 30A 110V connection, the previous owners did that but had one of the 3 aircon units off to do*it because the third would be just too much.* On that basis a 110V 50A supply would seem ideal especially as at $80 it is only a bit more than a 30A at $72/month.* Two 30As to give 60A total*however add up to $144 a whole lot more!

*
*From what the marina has said, it*sounds like they are supplying 50 amp 208V 3 phase to the slip they have open for you from which you could get two 50 amp 115V circuits.* When you get there, I would ask your friendly local marine electrician to help you put the cord together based on what you actually have both at the dock and on the boat to make sure you aren't hooking 30 amp cable to a 50 amp supply.*
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Old 08-24-2011, 09:13 AM   #35
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RE: Looks like I have avoided a fire

Quote:
bobc wrote:RickB wrote:bobc wrote:I discovered that my 30A breaker, which was the right size, had the hot lead paralleled across both breakers, rather than switching both the hot and the neutral.** In effect, I had a 60A breaker.*
You might want to review your electrical laws.
*

*With two breakers in parallel, the current is split half the current through one, half through the other (assuming equal resistance of the contacts).* This means the combination can pass a total of 60A with each breaker conducting 30A.* I think I'm on safe ground here.

*Bob, the NEC requires that paralleled CBs be factory assembled to function as a unit.* If you're going to leave this as is and to conform to the intent of the NEC, you*should probably make*sure that there is a connector between the switches so that if one trips, the other does as well.*
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Old 08-24-2011, 10:17 AM   #36
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RE: Looks like I have avoided a fire

Quote:
Delfin wrote:Robin wrote:
Well whilst us in yoorup have been asleep it seems battle commenced in the USA!*

I was at least right about one thing, the USA AC systems are very confusing!* Sorry if I opened a can of worms with my questions.

I think we will just hope that our 110V will somehow be connectible, via the cords and adapters*that came with the boat,*in our allocated slip when we get back there.* Our boat is currently out of the water in St Augustine FL patiently waiting for us to get sold up here and return...**

I asked for a 110V 50A connection if possible, the marina said:-

It'll have a 50amp 208v electric hookup, which you can split down to (2) 30amp cords.**Of course, you'll have to have a splitter.**Should a slip with (2) 30's comes open, I can simply change slips for you.

They list 110V 50A at $80/month and 208V/50A at $160/month or 110V 30A at $72 (per cord).* I'm concerned on two counts, one that we can get 110V on board but two that $80/month is a whole lot better than $160!* We know we can run almost everything*on a single 30A 110V connection, the previous owners did that but had one of the 3 aircon units off to do*it because the third would be just too much.* On that basis a 110V 50A supply would seem ideal especially as at $80 it is only a bit more than a 30A at $72/month.* Two 30As to give 60A total*however add up to $144 a whole lot more!

*
*From what the marina has said, it*sounds like they are supplying 50 amp 208V 3 phase to the slip they have open for you from which you could get two 50 amp 115V circuits.* When you get there, I would ask your friendly local marine electrician to help you put the cord together based on what you actually have both at the dock and on the boat to make sure you aren't hooking 30 amp cable to a 50 amp supply.*

*Thanks again.* This is their rate list below.* Would you therefore*expect to be charged (liveaboard rates) at $160 per month in red below for being connected to a 208V/50A or to be charged $82/month in blue below*for taking 50A 125V split from 50A outlet??* There is nearly $1,000 per year difference between the two options!* I don't want to be paying for what we don't need just because that is the only connection they have and it is a fixed cost not metered.*
<table class="easy-table-creator tablesorter" style="width:500px;height:108px;"><thead><tr><th>E lectric 120V 30 Amp, Per Outlet</th></tr></thead><tbody><tr><td>Daily</td><td>$6.00</td></tr><tr><td>Weekly ( 7 days or more)</td><td>$36.00</td></tr><tr><td>Monthly</td><td>$40.00</td></tr><tr><td>Live Aboard (Monthly)</td><td>$72.00</td></tr></tbody></table><table class="easy-table-creator tablesorter" style="width:500px;height:108px;"><thead><tr><th>E lectric 208/220V 50 Amp, Per Outlet</th></tr></thead><tbody><tr><td>Daily</td><td>$10.00</td></tr><tr><td>Weekly (7 days or more)</td><td>$60.00</td></tr><tr><td>Monthly</td><td>$82.00</td></tr><tr><td>Live Aboard (Monthly)</td><td>$160.00</td></tr></tbody></table><table class="easy-table-creator tablesorter" style="width:500px;height:108px;"><thead><tr><th>E lectric 125V 50 Amp Split From 50 Amp Outlet</th></tr></thead><tbody><tr><td>Daily</td><td>$7.00</td></tr><tr><td>Weekly (7 days or more)</td><td>$42.00</td></tr><tr><td>Monthly</td><td>$45.00</td></tr><tr><td>Live Aboard (Monthly)</td><td>$82.00</td></tr></tbody></table>
*
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Old 08-24-2011, 10:27 AM   #37
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RE: Looks like I have avoided a fire

$82 a month on the 120V / 50 Amp split is going to be two 120V / 30 Amp cords off of the 50 Amp splitter.* That's about what my summer bill is with both A/C running and I don't live aboard but I*am there about 20 days a month.

Seems reasonable.
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Old 08-24-2011, 10:58 AM   #38
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RE: Looks like I have avoided a fire

Quote:
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*I gather you have a 50 amp 115V connection on board, so that is clearly the best option.*
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Old 08-24-2011, 11:03 AM   #39
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RE: Looks like I have avoided a fire

Quote:
JD wrote:
$82 a month on the 120V / 50 Amp split is going to be two 120V / 30 Amp cords off of the 50 Amp splitter.* That's about what my summer bill is with both A/C running and I don't live aboard but I*am there about 20 days a month.

Seems reasonable.
*That is what I'm really really*hoping it means!* We have propane cooking and 440W of solar panels contributing to our own 12V*power and our fridge, freeezer and icemaker can all run off 12V*so we are not overly power hungry if we choose.* We know*our two main*aircons run off one 30A hookup but the third one just trips the breaker so 50A would seem perfect for all options pretty well, but we probably never need all three on together anyway.* 20 days per month more than*consitutes live aboard rates it seems as the rules are 8 days consecutive or 12 days in any month I think.* Fairest of course would be metered maybe.
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Old 08-24-2011, 02:41 PM   #40
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RE: Looks like I have avoided a fire

Quote:
Robin wrote:JD wrote:
$82 a month on the 120V / 50 Amp split is going to be two 120V / 30 Amp cords off of the 50 Amp splitter.* That's about what my summer bill is with both A/C running and I don't live aboard but I*am there about 20 days a month.

Seems reasonable.
*Fairest of course would be metered maybe.
*Mine is metered.* So days don't count.

I did understand that you have two 120V /*30 Amp*receptacles on your boat do you not?* Thus a 50 Amp split.
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