# AC,DC,DCC...I feel silly with this one...



## Brakeman Jake (Mar 8, 2009)

I've worked in automotive electricals for years,so DC is natural to me.AC...as long as it is single phase 110VAC,I'm OK.Beyond,AC is a mistery to me but I don't need to know.DCC,like you guys,I learned here and I'm good too.

But I'm puzzled with this one...my MRC power supply says:
Output-23VDC,18.5VAC Total 17VA...can someone tell me what the 17VA means?Have a giggle,I don't mind,I still want to know please.


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## fcwilt (Sep 27, 2013)

Brakeman Jake said:


> I've worked in automotive electricals for years,so DC is natural to me.AC...as long as it is single phase 110VAC,I'm OK.Beyond,AC is a mistery to me but I don't need to know.DCC,like you guys,I learned here and I'm good too.
> 
> But I'm puzzled with this one...my MRC power supply says:
> Output-23VDC,18.5VAC Total 17VA...can someone tell me what the 17VA means?Have a giggle,I don't mind,I still want to know please.


See the following:

https://en.wikipedia.org/wiki/Volt-ampere

Frederick


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## Brakeman Jake (Mar 8, 2009)

If I understand the technical terminology right,the part that says "maximum output is VA rating divided by nominal output voltage" means that if I want to use this power supply to power locos at 12VDC (max),this calculation applies:

17VA divided by 12=1.4 amps in DC available but then I wouldn't have any power left for AC.

Since I won't use the DC (I have DCC),I'm interested in the AC supply of this PS so the formula then is...17VA divided by 18.5=0.9 amps AC assuming I don't use DC.Am I right?If so,this current isn't impressive...I'll need to buy an AC power supply.


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## highvoltage (Apr 6, 2014)

Your math is correct, less than an amp. Which MRC unit do you have?


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## Brakeman Jake (Mar 8, 2009)

An aging but still new MRC 220


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## Lemonhawk (Sep 24, 2013)

If the DC output is 23 volts then to determine the current its 17/23, so the power supply produces less than an amp on either output if used separately. What does the unit need for a power supply? 23 VDC or 18.5 VAC both seem a little high.


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## Brakeman Jake (Mar 8, 2009)

These numbers are stated on the end of the power supply (MRC 220).I won't use it to power trains,so the 23VDC is irrelevant to me.It's the AC that I might have used if it had been sufficient but it's not.

I need [email protected] for my purpose.


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## Lemonhawk (Sep 24, 2013)

They these power supplies:
https://www.jameco.com/z/RS-75-15-M...ngle-Output-15-Volt-5-Amp-75-Watt_323602.html.


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