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Power Electronic Circuits Work As Soft Starter Of Induction Motor


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#1 suma

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Posted 30 June 2007 - 10:30 PM

hi all,
i need power electronic circuits that wark as soft starter of induction motor,using SCRs and TRIACs.

#2 marke

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Posted 02 July 2007 - 09:50 AM

Hello suma

The power circuitry is very simple, it requires an AC switch in series with one or more phases to the motor. the AC switch can be a triac, a reverse parallel connected SCR diode or reverse parallel SCR SCR circuit.

Se http://www.lmphotonics.com/sstart.htm
It is that simple, the problems are in the control systems.

Best regards,

#3 zara

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Posted 11 January 2008 - 06:14 PM

What rating should be used if the SCR is directly connected to the 220V 50Hz power cord?

#4 marke

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Posted 11 January 2008 - 08:06 PM

Hello zara

The voltage rating of the SCR should be at least 3 times the voltage of the AC supply.
For a 230 volt supply, the voltage should be 690 volts.

Best regards,

#5 zara

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Posted 12 January 2008 - 04:34 PM

Thanks, marke.
This voltage rating is rms voltage rating, right? How about the current rating should be used if the load is 1000W which is also connected to power cord supply directly? Normally the current rating is rms rating or average rating?

#6 marke

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Posted 12 January 2008 - 10:05 PM

Hello zara

QUOTE
voltage rating is rms voltage rating, right?
Correct
QUOTE
How about the current rating should be used
You should calculate the junction temperatures and ensure that the junction temperature of the SCRs do not exceed the maximum rated junction temperature.
The junction temperature is a function of the SCR thermal characteristics and the heatsink characteristics.

Best regards,




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