Star Delta connections regarding motors

[mark123]

Hope someone can help, Basically i'm just getting into heavy industrial and when i have been opening various panel's and motors i can't get my head around the actual terminating of star,delta from the panel to the motor as they seem to move L1,L2,L3 to L2,L3,L1. Any ideas?

 

[THE DUKE]

Hi delta connection is U1 TO V2 V1 TO W2 W1 TO U2
or as you have L1 TO L2 L2 TO L3 L3 TO L1 Hope this helps sorry don't know how to insert a diagram have a look at this site it might help Patchn - Home

 

[silva.foxx]

Star Delta can be a little confusing, so you're not alone. I know sparks who won't even touch it!

The above image is of alternative wiring. Note at the delta contactor that the phases swap.

Basically you have to follow the wiring from the supply side of the line contactor, through the motor windings and back through the delta contactor back to the supply, so that you start at one phase and end at another.

One other thing:

Overloads; if before the line contacor and delta contactor, as in a motor breaker, set at 100% of motor's flc (full load current)

If after the line contactor then set at 58% flc

Another tip: setting the star to delta transistion time. Clamp a phase with an ammeter. Start the motor in star and watch the current rapidly rise then settle for a second. Once the motor has started the current will rapidly fall. Its at this point that, nearing the end of the fall, that the timer should switch over to delta. If the timer is set too short ie. before the current falls then the overload or motor breaker will trip! High inertia loads, such as fans / flywheels, will take longer to start up so the timer may be well in excess of 10 secs.

Regards
Richie

 

[mark123]

Thank's all, sort of simple if you just engage your brain. Cheers.

 

[silva.foxx]

It gets even more confusing at 3am when you need to reverse the direction of rotation!

Regards
Richie

 

[welshmadness]

It gets even more confusing at 3am when you need to reverse the direction of rotation!

Regards
Richie

Ohh yeah, been there, done that, but without the safety net of spare fuses incase i fudged it up.

 

[oldun]

Don't you just swap two connections over, from the same set of wires ie U1, V1 etc at the motor.

 

[oldun]

Hi delta connection is U1 TO V2 V1 TO W2 W1 TO U2
or as you have L1 TO L2 L2 TO L3 L3 TO L1 Hope this helps sorry don't know how to insert a diagram have a look at this site it might help Patchn - Home

Basically two parallel and one crossed, as I was told 30 years ago!

 

[ipf]

Spot on oldun.