rectifier bridge without transformer- problem?

[milosz125]

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.

Greets

 

[FvM]

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

Yes, the DC- ground connection in your schematic must be deleted.

Most devices with mains connected rectifier are connected this way, e.g. switched mode power supplies, motor inverters, DC motor drives.

Are there any regulations concerning AC/DC system interaction?

Don't draw DC current from the mains supply (bridge rectifier required), safe isolation of all mains connected circuit parts, preferably PE connection of accesible metallic parts.