Transformer

[mrmiles8]

A relative of mine has a set of Christmas lights who's transformer has died

He states the label says "220-240vac, 50hz, 15va, SEC: 24vac, Max. 10va" and he wants to replace with one that says "230-240 50Hz. 24v - 300mA 7.2VA"

The question is will it be ok?

I'm afraid that's all the information I have

 

[OnOff]

The replacement transformer may or may not be a tad small for your requirements. The "va" stands for volts x amps or "watts" as it's also known. The easiest formula used in all this is P = I x V where P = watts, I = amps and V = volts. So the secondary side of your existing trannie  is 10VA ..........or 10W.

So using the formula we have 10 = 24 x A. To find A we divide 10 by 24 giving us 0.416A or 416mA. Your replacement transformer offers only 300mA (the calc would be 7.2 / 24 giving 0.3A) hence my comment it might be a bit light for your requirements. It may be that the original trannie is over specified or it might itself be right on the limit. 

It will possibly work but may run HOT as it's having to work too hard, and HOT can mean failure. How many lights? Anything written on them or is is some flash control box with running lights etc?

On the PLUS side he's got 12 months to sort it out!

Maybe pop down to Maplin and ask about something like this:

http://www.maplin.co.uk/ac-ac-fixed-voltage-high-current-power-supplies-240

 

[Doc Hudson]

As onoff suggests the new transformer has a lower output power. Looking at it in percentage terms the replacement item is only 72% of the output capacity of the original. Or, you will be losing 28%, (over one quarter), of the original output capacity. It could well start overheating the transformer if left running for a long time. As a general rule if fitting a replacement transformer you need to be equal to to greater then the original output capacity for it to work satisfactorily.

Doc H.   

 

[ProDave]

NOW is the time to buy a new set of lights being sold off cheap in the sales.  Usually hardly worth bothering trying to fix them.

 

[Andy™]

A relative of mine has a set of Christmas lights who's transformer has diedHe states the label says "220-240vac, 50hz, 15va, SEC: 24vac, Max. 10va" and he wants to replace with one that says "230-240 50Hz. 24v - 300mA 7.2VA"

The question is will it be ok?

I'm afraid that's all the information I have

your transformer is 10va. alternative is less

also, you dont state if replacement is AC or DC

 

[mrmiles8]

Thanks for all your responses

I tend to agree that it would be easier to dispose of the set in question but I think there may be some sentimental value to them

I don't suppose any one knows where he could get a replacement transformer, he said he's tried all the obvious places (obvious to us laymen any way)?

 

[Andy™]

cpc.co.uk

 

[Andy™]

this one would do - £7.01 + VAT + P&P

clicky

 

[SPECIAL LOCATION]

this one would do - £7.01 + VAT + P&P
clicky

Wot Andy said if you have GOT To keep the lights...

If not..

wot ScottyDave said...

bin em..

buy some cheepo sets...

even LED's so less power as well!!!!

Guinness

 

[mrmiles8]

Thanks, Andy, think I've convinced him to go for the CPC one - just got to wait for them to have a "carriage free" weekend now

 

[Andy™]

or just buy some other stuff. im sure you will find something useful that will get you free P&P