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Old 03-25-2013, 08:17 PM
milosz125 milosz125 is offline
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Default rectifier problem

Hello All

I have problem with electric drive project.

The drive consist of 220V DC motor (classic with brushes ) and control circuit which controls the motor. Motor is controlled in left/right style via two contactors.

The available power supply is 230 V AC 50 Hz (European type) 1 phase - TN-C type (L and PEN wires).

To supply the motor, a bridge rectifier is used. However without seperation transformer; drawing is attached to post.

My question is , is it done correctly to supply that motor in that configuration ?

What type of system is that part behind bridge?
I think grounding should be done carefully because if negative (-) wire of DC side will be grounded, it causes (when AC current starts to flow in negative period) high faulty current flow from source, through earthing, (-) wire, diode D1 and to source (V1).

So in DC side connection between negative wire and PE wire is not allowed.

Anyway designer of that circuit claims that everything is correctly designed.

Are there any regulations concerning AC/DC system interaction?

Please help.


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Old 03-25-2013, 09:41 PM
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BillB3857 BillB3857 is offline
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Look at your circuit. Does it make any sense at all to have ground at both ends of the lower right diode? Likewise, you are right about high currents through D1 on the negative transitions of the AC line. Remove the ground from the motor lead.
Old 03-26-2013, 12:07 AM
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Bill_Marsden Bill_Marsden is offline
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This is very close to being a transformerless power supply, which is against our Terms of Service. I am going to close this thread due to this.
"Good enough is enemy of the best." An old engineering saying, Author unknown.

General info:
If you have a question, please start a thread/topic. I do not provide gratis assistance via PM nor E-mail, as that would violate the intent of this Board, which is sharing knowledge ... and deprives you of other knowledgeable input. Thanks for the verbage Wookie.
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