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Too many volts?

cereal tiller

By cereal tiller
in Boat Building & Maintenance

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cereal tiller Veteran

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Posted
Posted (edited)

Have installed a new Inverter,the previous Mastervolt one packed up after 11 years service.

 

The new one is working well but is has an output voltage of 263 .

 

If 5 AMP A.C. load is applied the voltage drops to 244.

 

All equipment including T.V.and phone/laptop chargers work O.K.

 

Anyone have any thoughts on whether this higher than usual voltage will affect the boat's electrics over the long term?

Edited by cereal tiller
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Keeping Up Veteran II

Keeping UpDonate to Canal World

Posted
Posted

If it is a pure sine wave inverter, that is rather high. If it is a modified sine wave, however, it may be just that your meter is reading it as too high when in practice it is OK

 

If it is a too high a voltage, some items of equipment could die instantly, some won't notice the difference, but most will probably run a little bit warmer which could shorten their life in the long term.

 

If I had a brand new sine-wave inverter I would be questioning whether or not it could be faulty and whether the fault would get worse in the long term. But with a modified sine wave I'd just assume that my meter didn't like it, and ignore it.

 

One way to test would be to use a shore-line as a reference, and a pair of lamps with old-fashioned filament bulbs. If they are the same brightness then all is OK so blame the meter.

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nicknorman Veteran II

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Posted
Posted (edited)

You are probably exceeding the maximum design voltage of various components connected to that supply.

 

However, it would first be worth contemplating what sort of inverter you have bought. If it is a MSW one then the non-sinusoidal waveform may upset your meter's ability to measure correctly. Is suspect that a near-square waveform with a peak voltage of say 230v would read much higher than that on a meter expecting a sine wave.

 

Although you say that the voltage drops significantly when you apply a load, it could perhaps be that the waveform is becoming more sinusoidal rather than the peak voltage decreasing.

 

But of course if you tell me that your new inverter is PSW and a reasonably good make (ie actually PSW rather than PSW on the marketing blurb) then the above is rubbish!

 

ETA x-posted with KU but at least we agree!

Edited by nicknorman
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cereal tiller Veteran

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Posted
  • Author
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If it is a pure sine wave inverter, that is rather high. If it is a modified sine wave, however, it may be just that your meter is reading it as too high when in practice it is OK

 

If it is a too high a voltage, some items of equipment could die instantly, some won't notice the difference, but most will probably run a little bit warmer which could shorten their life in the long term.

 

If I had a brand new sine-wave inverter I would be questioning whether or not it could be faulty and whether the fault would get worse in the long term. But with a modified sine wave I'd just assume that my meter didn't like it, and ignore it.

 

One way to test would be to use a shore-line as a reference, and a pair of lamps with old-fashioned filament bulbs. If they are the same brightness then all is OK so blame the meter.

 

Yes,it is a pure sine wave inverter.

 

have checked the output with a Fluke multimeter and several other devices

 

The high voltage is consistent with all of them

 

have informed the suppliers who have in turn contacted the manufacturers

 

Tried Henry hoover on the inverter,it seems to have more 'suck' than usual!

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cereal tiller Veteran

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Thanks for the replies folks

 

Will wait to see what the manufacturer has to say.

 

the high voltage only became apparent when i installed a volt/amps meter adjacent to the inverter,one likes to keep an eye on consumption.

 

I considered that the new panel meter may have been 'fibbing',it transpired that it is accurate enough for the job

 

In the mean time i hope that i don't hear the sound of capacitors a'popping!

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smileypete Veteran II

smileypete

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Posted (edited)

Switched mode supplies often have 400V caps on the mains side so in theory should be able to handle a pure sinewave of up to 280V RMS which gives 400V peaks.

 

Trouble is a distorted sine wave say from a genny may read as say 270V on a true RMS meter, but give a peak voltage well above 400V. help.gif Something that can measure peak voltage like a scope is the only way to tell for sure.

 

For the OP returning the inverter is the ideal option, but IF that's not possible there may be something in there that can be found and adjusted by someone with the right skills and competencies.

 

I'd expect for a pure sine inverter the output is at least reasonably close to a pure sinewave, seems the cheap or defective non inverter gennies '2 pole' are the usual culprits for smoking things, especially when unloaded. wacko.png

 

cheers, Pete.

~smpt~

Edited by smileypete
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cereal tiller Veteran

cereal tillerDonate to Canal World

Posted
  • Author
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Have installed a new Inverter,the previous Mastervolt one packed up after 11 years service.

 

The new one is working well but is has an output voltage of 263 .

 

If 5 AMP A.C. load is applied the voltage drops to 244.

 

All equipment including T.V.and phone/laptop chargers work O.K.

 

Anyone have any thoughts on whether this higher than usual voltage will affect the boat's electrics over the long term?

 

Well,the inverter has displayed an output voltage of 237!

 

But,only when the battery voltage is reduced to Eleven volts

 

 

i connected a single battery to it and allowed it to discharge slowly

 

Previous experience with inverters has always shown the the output voltage is consistent even though the battery voltage varies.

 

 

After a test with an 800 watt resistive load the output voltage increased momentarily to 293.

 

any thoughts?

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by'eck Veteran

by'eck

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Posted

A perfect square wave will have a root mean square voltage (Vrms) equal to its peak voltage. Your AC meter will measure Vrms for a perfect sine wave, so anything between the two such as modified sine wave will tend to read higher.

 

You haven't mentioned what make/type your new inverter is.

 

A load will probably change the wave shape of an MSW inverter output and hence the measured voltage. The only true answer is checking the output on a scope.

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Keeping Up Veteran II

Keeping UpDonate to Canal World

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I had a Sterling PSW inverter a few years ago which had this same voltage level and turned out to be running at 60Hz too (the major clue was that the clock on the cooker was running 20% fast).

 

Oddly enough, Sterling said that the particular model didn't even have a 60Hz option - but I wonder if it had one that the manufacturer hadn't told them about.

 

Anyway they changed it instantly with no quibble.

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