Low shorepower voltage

[andyball]

Having found a paltry 195-198 Volts aboard, when 14-16Amps being drawn.....have replaced cables & blagged larger (though still not huge) shorepower cable & can now manage a dizzy 207 Volts.

found that we're losing a volt or two on board, 7 Volts along 40m of shorepower cable, and are only getting 215-220V approx at the shorepower point on the pontoon end ,although on the quayside (120m+ closer to the real mains), it's up to 12Volts more; all depending on how mnay other people are boiling kettles, of course.

Does anyone get a lower voltage than that?

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[charles_reed]

You'll quite frequently find, at the end of power supply cables voltage drops of up to 40 volts, ie down to 200 v.
The one thing that is invariable is the cycle rate.

If you were to carry out the same exercise at home you'll find a similar situation.

Some years ago a neighbour and I were recording volts in the 180s - and took to haranguing MEB (as it the was). After about 6 weeks of continual daily criticism they changed the substation transformer. The crew came round and told us that we were both on the same phase of a faulty transformer, which they'd reported when they'd fitted an (allegedly) re-con transformer.

The volts are much more consistent in France - but then the EDF has a much more modern grid system than ours in the UK. But you can still get voltage drops where the wiring isn't up to the current draw.

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[Strathglass]

There is a minimum and maximum supply voltage requirement for the supply to domestic consumers by the electric suppliers.
It is something like 240 + 6% - 15% but as those figures are from memory sometime in the distant past I may well be wrong with the exact voltages.

I doubt if this will apply to 'subcontracted power' such as in marinas.

Iain

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[byron]

<font color=blue>I am far from being a knowall on this subject indeed I am a knownowt if anything. However, when we lost our souls and became part of Europe wasn't the standard set at 220v ?
Our stuff remained at 220-240 because it didn't hurt it to be so. Ergo the +6% -15% would apply to 220 v. Gosh! I hope you understand that, I don't and I wrote it /forums/images/icons/wink.gif
As a matter of interest and dealing with voltage drop. I ran an extension cable 330 yards from my house to the boat and the voltage drop was only 3 volts.

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[poggy]

Hi,

I think that the UK voltage is now set at 230V as a compromise with the Euro 220V. Really the standard was set with quite a variance, so although they dropped it to 230V, it is still within the original spec anyway.

Poggy

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[HaraldS]

Well, you were not the only ones to suffer change. Euroland went up from 220 to 230 to meet. This happened here a few years ago and I remeber increased light bulb failures. All new ones are now labeld 230V. Just plugged the meter in and it showed 229V.

Back to boats: On my boat inverter and gernerator do exactly 230V. I have a Volt, Amp and frequency meter in my AC panel on board and from shore I have often seen less than 200V. I think some marina installations are at their limits.

If you have critical decives you could run them indirect via the inverter. Modern chargers seem to have huge input tolerance.

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[andy_wilson]

241.2 Volts in Holmfirth last weekend

And that wasn't enough to get the pump going on my central heating.

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[Rowana]

Volt drop in a cable varies as the square of the current drawn.

Power in watts = Volts times Amps W=I*V
Ohm's law - Volts = Amps Times Resistance V=I*R

Now if we combine the two together - W=I*(I*R) which =I(Squared)*R

But of course you all knew that ! !



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[saturn]

the nominal voltage in the uk is still 240 volts.locally it will vary depending on time of day/year, most likely reason is that marina loads are increasing but not the means of supply.

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[VicS]

Volts drop along a cable is propotional to the current Ohms law

You are bringing power (watts) into the poblem falsely

If you want to talk about the power dissipated in the cable then thats proportional to I squared W=I^2 X R

Heck how do you type a superscript on the forum?

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[saturn]

andy,
is it a problem for all berth holders?.(i am not going to go all technical)
you need to get together and agree to switch off your electrics(ac) and measure the voltage arriving at the marina point of supply,this will tell you what is available before you start switching stuff on.
if the voltage is still low then the marina will have to be involved in doing something about it ,which will probably cost them money.
i would guess that with a voltage as low as you say that the ac loads have gone up over time but the power supply has not.

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[Rowana]

True. But what I was trying to point out is that the power lost in the cable is proportional to the square of the current, therfore if you are drawing a fair load, you have a fair old power loss.

Which just goes to prove that size Is important! (in some things, anyway)

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[J_Priedkalns]

You could try using an adjustable isolation transformer to compensate for the low shore power input. By adjusting the primary voltage taps to match the low input voltage, you will get the required voltage on the secondary side to run your equipment. We use one on our boat and it certainly works at some older marinas where the AC supply was in question. The primary is adjustable from 100v AC to 240v AC in 10v increments. The secondary is wired for a fixed output of 120v AC or 240v AC. The rating of my transformer is 5KVA which is overkill but runs cool and is noise free. Our system is wired for 120v AC on the secondary as all our AC equipment is North American (including Canada).

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[andyball]

Good idea, thanks.

That boat's off to another marina soon, so hopefully the supply'll be rather better.



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