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Power switch amp rating question
Power switch amp rating question
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Old 9th April 2020, 07:58 PM   #1
Pygmy is offline Pygmy  Netherlands
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Default Power switch amp rating question

So I've pieced together components for my Class D amp, including a powerswitch,and I just want to confirm with you that this will work safely, as I'm still learning about electronics. :-/

The powerswitch is rated at 5A.

I've got a Connex SMPS600RS that converts 220V AC to 38VDC.

The Amp board is specced to use 18.1A max current.

The way I understand it is that 19A x 38V = 772 Watt;
772 / 220 = 3.5 ampere.

Am I correct in understanding that the powerswitch on 220V will get a max amperage of around 3.5A, and therefore this powerswitch should be safe to use?
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Old 9th April 2020, 08:20 PM   #2
rayma is offline rayma  United States
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Should be ok, since the switch is rated at 250VAC.
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Old 9th April 2020, 10:54 PM   #3
Pygmy is offline Pygmy  Netherlands
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Quote:
Originally Posted by rayma View Post
Should be ok, since the switch is rated at 250VAC.
Point taken. My worry was about it being rated at 5 ampere, while the Amp states drawing 18.1 ampere max.

But that's from the 38V SMPS.

So if my really bad electronics skills have not forsaken me, will at max draw (19A * 38V =) 772 Watts.

And 772 Watts from the 220v mains should at max result in a 3.5 ampere draw from the mains / through the power switch..?

Sorry if this is beginner's stuff, but hey.. I'm a beginner just trying to get the hang of it. :-/

Last edited by Pygmy; 9th April 2020 at 10:56 PM.
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Old 9th April 2020, 11:27 PM   #4
nigelwright7557 is offline nigelwright7557  United Kingdom
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38V * 18A = 684W
684W/220V = 3 amp primary.
So 5 amp switch is ok.
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Old 9th April 2020, 11:36 PM   #5
rayma is offline rayma  United States
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Quote:
Originally Posted by Pygmy View Post
My worry was about it being rated at 5 ampere, while the Amp states drawing 18.1 ampere max.
Yes, the switch is in the primary, so it only sees the current from the 220VAC.
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Old 10th April 2020, 09:23 AM   #6
russc is offline russc  England
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And, for that current you would be switching off your amplifier whilst playing at FULL VOLUME.
Normal switch off with no music, current would be much less.
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Old 10th April 2020, 11:37 AM   #7
Mark Tillotson is offline Mark Tillotson
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Its the inrush current on switch-on that will weld a switch shut, fortunately that Connex
power supply has soft-start according to its data, so all should be fine.
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Old 10th April 2020, 02:36 PM   #8
Vovk Z is offline Vovk Z  Ukraine
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And those switches are in two variants - bistable and push-button. TS may need bistable?
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Old 10th April 2020, 02:42 PM   #9
nigelwright7557 is offline nigelwright7557  United Kingdom
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Quote:
Originally Posted by Mark Tillotson View Post
Its the inrush current on switch-on that will weld a switch shut, fortunately that Connex
power supply has soft-start according to its data, so all should be fine.
The difference in price between 5 amp and 13 amp switches isn't much anyway.
The good thing about AC is it turns off twice every cycle so isn't as prone to arcing as DC.
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