Why 220V?

[O C Diver]

If you re-read the part in parenthesis it says "less energy consumed for the same output". That is incorrect. You only get out what you put in (Wattage) minus heat and mechanical losses.

The output being referred to is not KW, it's HP or in the case of air conditioning BTUs.

Ted

 

[ronobrien]

The output being referred to is not KW, it's HP or in the case of air conditioning BTUs.

Ted

It's all the same, Wattage. Hp (742 W/HP) BTU (3.41 BTU/W). You can neither create nor destroy energy, you can only convert it. In this case it is electrical energy being converted to another form of energy, but Wattage is at the heart of it all and wattage is V X A. If you change the voltage you have a corresponding change in amperage to achieve the same wattage, or said another way, the amount of work you are trying to accomplish be it heat or mechanical.

 

[O C Diver]

It's all the same, Wattage. Hp (742 W/HP) BTU (3.41 BTU/W). You can neither create nor destroy energy, you can only convert it. In this case it is electrical energy being converted to another form of energy, but Wattage is at the heart of it all and wattage is V X A. If you change the voltage you have a corresponding change in amperage to achieve the same wattage, or said another way, the amount of work you are trying to accomplish be it heat or mechanical.

Sorry, it doesn't work that way. Pick up a W W Grainger motor book and you will see same HP, RPM, and frame electric motors in 120, 220, and 220 3 phase with different efficiency numbers and power consumptions. Want greater efficiency; it costs more; but you save money long term in lower electrical consumption.

Go to a store selling air conditioners. There required to have an Energy Guide so you can compare compressor energy efficiency for the same BTU rating.

Ted

 

[ronobrien]

Sorry, it doesn't work that way. Pick up a W W Grainger motor book and you will see same HP, RPM, and frame electric motors in 120, 220, and 220 3 phase with different efficiency numbers and power consumptions. Want greater efficiency; it costs more; but you save money long term in lower electrical consumption.

Go to a store selling air conditioners. There required to have an Energy Guide so you can compare compressor energy efficiency for the same BTU rating.

Ted

First it's hard to compare single phase with 3 phase. With regard to efficiency ou are talking about the power factor which is current leading. That needs to be matched with the usage. If you use a motor with a power factor not matched to the use it actually becomes less efficient instead of more. The cost doesn't necessarily translate into "more is better".Those are the nuances I refered to in my original post about "that's for the engineers". My comment was in reference to the general statement that using 220 vs 110 creates more output with the same or less energy. You can increase efficiencies but the statement that you get more work out by switching to 220v is patently wrong.

 

[KnotYet]

Sorry, it doesn't work that way. Pick up a W W Grainger motor book and you will see same HP, RPM, and frame electric motors in 120, 220, and 220 3 phase with different efficiency numbers and power consumptions. Want greater efficiency; it costs more; but you save money long term in lower electrical consumption.

Go to a store selling air conditioners. There required to have an Energy Guide so you can compare compressor energy efficiency for the same BTU rating.

Ted

It should be noted that the efficiency of an AC motor is determined by its design,
quality of the materials used in its manufacture and its appropriateness to its use.
Marketplace decisions dictate the resulting efficiency of a motor not its voltage.

This makes it difficult to compare apples to apples because a motor with 120V
on its nameplate could be nearly identical internally to a similar 220V version.
In such a case the design would yield somewhat greater efficiency in 220V use.

There is a correlation with HP and efficiency. The highest HP motors can achieve
the highest efficiency independent of voltage though higher voltage will normally
be employed. Higher AC frequency also has a positive correlation with efficiency.

 

[Circumnavigator]

My screen shows that Marinco's part number CS503-25 is a 125V 50 Amp 25' long cordset. To use it safely in a 125/250 50 Amp outlet you would have to first remove the original male plug and install a new 125/250 50 Amp male plug, wiring it up appropriately.

Perhaps what you meant to say was to use Marinco's adapter P504-503 or 123A, both of which would work.

I'm not sure what you're looking at nor am I certain what is at the shore end of Marinco CS503-25 -- I think it's a standard 125/250 - 50 4 wire plug, but their PDF doesn't say. All I know for certain is that Morning Light has a commercially made 120 volt - 50 amp shore power cable with a standard 125/250 - 50 4 wire plug on the shore end and a 120 - 50 3 wire connector on the boat end. It's factory made, with sealed ends, not a retrofit.


Jim

 

[luna]

I was looking at the specs. for the Marinco part number you referenced, which should be attached.

If so, it clearly shows that both ends are for 125V 50 Amp outlets and receptacles, as they are SS1 series connectors. 125/250V 50 Amp cordsets use SS2 series connectors.

Perhaps you have a factory made unicorn.

View attachment CS503-25_SPEC.pdf

 

[diver dave]

It's all the same, Wattage. Hp (742 W/HP) BTU (3.41 BTU/W). You can neither create nor destroy energy, you can only convert it. In this case it is electrical energy being converted to another form of energy, but Wattage is at the heart of it all and wattage is V X A. If you change the voltage you have a corresponding change in amperage to achieve the same wattage, or said another way, the amount of work you are trying to accomplish be it heat or mechanical.

The trap is many nonUS electrical motors spec the output in kW. So it is confusing for some that are more familiar with mechanical work expressed in HP.

 

[tiltrider1]

I was looking at the specs. for the Marinco part number you referenced, which should be attached.

If so, it clearly shows that both ends are for 125V 50 Amp outlets and receptacles, as they are SS1 series connectors. 125/250V 50 Amp cordsets use SS2 series connectors.

Perhaps you have a factory made unicorn.

View attachment 141668

I think this argument is a bit silly. In the past I have taken 50a 125v cords and put 50a 125/250v ends on it. I did this because the dock only offered 50a 125/250v and I only needed 50a 125v. Later I changed the boat socket to 50a 125/250v in anticipation of bringing L2 to the boat. It never happened and now the owner runs around with a 50a 125v cord with 50a 125/250v ends.

The humor is when others see his very light cord set and want to know where they can get one.

 

[Circumnavigator]

I was looking at the specs. for the Marinco part number you referenced, which should be attached.

If so, it clearly shows that both ends are for 125V 50 Amp outlets and receptacles, as they are SS1 series connectors. 125/250V 50 Amp cordsets use SS2 series connectors.

Perhaps you have a factory made unicorn.

View attachment 141668

I'm not on the boat -- so I don't know what brand mine is. It seems unlikely that it's a unicorn.


In any case, the point is that it is perfectly possible and safe to use a 125/250 50 plug on the shore end of a power cord, wire only the black, white and green with a three wire cord, leaving the red blank, and use a 125 50 connector on the boat end.


Alternately, you could use a standard 125/250 50 cord and boat plug and only wire the three points inside the boat. That would be a four wire cord, somewhat heavier and fatter than what you really need.


Jim

 

[luna]

Jim.

I agree with what you have now stated as being safe, although in the latter option as I don't like an unconnected hot conductor, I would likely remove the prong from the male plug, and cut the red wire flush with the jacket so it can't make any connection.

Either way you do it, it is not a "factory made, sealed ends" cordset.

I'm unaware of anybody who makes what you say you have, except in pigtail form.

 

[psneeld]

Neither is a perfectly legal, up to code junction box or the inside of a CB panel.