OT: A Star-Delta wiring for 6-lead motor

[iant]

I am glad you cant do that here (2 contactors) but the operation of some soft starters are the same
1 or 2 phases permanently connected to the motor and the other controls the start
I am in favor of either VFD or soft starter

but there is nothing wrong with Star delta if it is setup correctly.
I noted that there is three black wires going away from the back bottom of the contactor marked 'STAR' that leads me to believe it is the DELTA contactor.
That is why I ask

any way bed time for me 1:30 am here

 

[Zimmer]

... If the low starting torque is insufficient to accelerate the load to about 90% speed before transitioning from Star to Delta, the current still spikes to AT LEAST LRC when the transition happens, often significantly MORE, because of a phase shift that takes place which can put the line current out of phase with the motor back EMF. Current spikes of over 2000% are theoretically possible. When that happens, people often attempt to lessen that transition spike by using the ONLY tool available in a Star-Delta starter, the transition timer. They think that by increasing the time before transition, the current will be lower, when in fact it cannot, it can ONLY be higher.

Unless the machine happens to be driving something like a centrifuge where the motor can be in "star" for 4-8 minutes, then lengthening the star timer, will in fact allow the machine to build speed, thus reducing the transition current.

 

[jraef]

Unless the machine happens to be driving something like a centrifuge where the motor can be in "star" for 4-8 minutes, then lengthening the star timer, will in fact allow the machine to build speed, thus reducing the transition current.

There is always an exception to every rule, but those are often specially designed motors specifically for centrifuges with extra thermal capacity in the rotors, and when you use them, you should over size the contactors and conductors to handle the added current for a longer time.

 

[Zimmer]

There is always an exception to every rule, but those are often specially designed motors specifically for centrifuges with extra thermal capacity in the rotors, and when you use them, you should over size the contactors and conductors to handle the added current for a longer time.

Absolutely m8.

I have seen in the past too, when a "power blip" occurred for a second, or someone bumped an emergency stop, the "clever" operator, realising the machine was still at full speed, would restart the machine, while reducing the time delay to close to zero, because he couldn't be bothered waiting 6 minutes. The machine would start fine, everybody happy except he would forget to put it back. Next time, carnage when starting from a complete stop.

 

[mjoubert]

If you use an off load star contactor, this can be substantially smaller than the Main or Delta contactor of the system provided. For this to work the Star contactor needs to energise 1st followed by the Main .... then de-energize the Star and energize the Delta contactor.