Need to design an AC load bank using HEXFETs

Mar 03, 2009 7 Replies

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Randy965 17 years ago

Hello,

I'm in the process of designing an AC load bank and I'd like to use a few paralleled HEXFET devices.

I need to load 120V 60Hz line at 5 amps for about 3 seconds. This is for testing the output of a AC power supply.

Would anyone care to share some circuit design tips or any ideas concerning connecting an N and a P channel device as my load?

My idea is to use an N channel device for to load the positive half cycle, and a P channel to load the negative half cycle in a totem pole configuration.

Thank you,

Randy

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Jan Panteltje 17 years ago

On a sunny day (Tue, 03 Mar 2009 06:54:36 -0600) it happened "Randy965" wrote in :

Use a brige rectifier and put the n-MOSFET with drain on + and source on -. And the AC on the ~ connections,.

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me 17 years ago

Jan Panteltje wrote in news:goja1v$m82$ snipped-for-privacy@news.datemas.de:

or you could use a triac and a resistor (or light bulbs)

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PeterD 17 years ago

And prehaps something to limit current to the requested five amps?

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Spehro Pefhany 17 years ago

Why not use an ordinary SSR or mechanical relay?

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Jan Panteltje 17 years ago

On a sunny day (Tue, 03 Mar 2009 09:01:47 -0500) it happened PeterD wrote in :

Sure :-) Small inductor, high PWM frequency? Old electric room heater?

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panteltje 17 years ago

for

Why not use a switch? Obamama will be happy you created an other job.

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Jan Panteltje 17 years ago

On a sunny day (Tue, 03 Mar 2009 06:54:36 -0600) it happened "Randy965" wrote in :

Ah, finally worked it out. Use a big capacitor, and a switch. You want only current, so the cap will give you 90 degrees phase shift. And the switch is to switch the cap on for 3 seconds. The value of the capacitor is, from I = U / R and Z = 1/ j.w.C, Z = U / I = 120 / 5 = 24 Ohm. C = 1 / j.w.Z = 1 / (6.28 x 60 x 24) = 1.1 10^-4 = 110 uF. Bipolar of course :-)

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