MICROMASTER MM440 and DC-LINK

I have 2 MM440's and I connected DC+ to DC+ and DC- to DC-. I changed parameter P1240 to 1 on both drives. I used fuses 15Amps.

The drives are 4kW

My question: why is it good to connect the DC Links ?

Redundant sharing? I do hate to answer a question with a question...

I don't think it's necessarily good or bad either way. This is an application specific thing.

If this is a sectional tensioning application, where one drive is pulling and the other is braking, then connecting the DC bus will allow you to use the energy from the braking drive to power the motoring drive. You also give yourself some extra bus capacity if only one of the drives is decelerating at a time. The other drives bus caps absorb some of the energy and/or use the energy to motor instead of pulling it off the AC line.
However, if both drives will be accelerating and decelerating together then connecting the DC bus between them probably won't help much.
It all comes down to energy sharing.

Keith

Without knowing the specifics of his applications... I ask again "redundant sharing?"

I'm not sure I'd mess with 600VDC if I didn't know why I was doing it .
However , a new gen Rockwell drive has the facility to pop all its regen energy back into a capacitor bank during regen braking , resulting in 80% energy savings when used on a repetitive quick transition start stop process .
Be very careful about bus sharing , can create terrible AC line noise .