Anyone know if this will work for star delta start without timer?

[Llareggub2]

953A576F-5DDB-4E43-A2D4-AE7C76C9EC36.jpg

[Bohdan]

A star/delta starter is used on three phase motors to limit the starting current by first using star connections and when the motor is up to speed switching to delta connections. Your 3 boxes give no indication of what they actually are so unless you have a speed sensor you have to use some form of delay to let the moter get up to speed before switching to delta mode.

[elanjacobs]

Here's the diagram for a manual star-delta switch if it helps


As with all electrical work; if you're not 100% sure, pay someone who is.

[ubeaut]

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[Llareggub2]

The start button is released after star windings get the motor up and running which kicks in the main and delta contractors

[Bohdan]

That will work as you are the timer. It is a common starting method where the ON button is held in until the motor gets up to speed. Often used on saws where it doesn't matter if the operator releases the button too early as the blade gets up to speed very fast. On machines that start under full load releasing the button too early may result in tripping the supply breakers.

[Llareggub2]

Thanks. It’s a 15 hp drum sander and starting on dol is asking a bit much I think as it is slipping the belt.

[Bohdan]

That will definitely take time to get up to speed so it may cause problems if an untrained operator starts it. I would be happier with a timer or at least a two position start sequence. A START position followed by a RUN position.

On a motor of that size I would have expected that it was already fitted with a star/delta starter.

[NCArcher]

On a motor of that size I would have expected that it was already fitted with a star/delta starter.

A photo in another thread shows a DOL setup.
You should just install a proper Star/Delta starter. In your drawing the motor is trying to start on delta before you hit the start button.
If you have to buy new contactors you might as well add a timer and wire in the appropriate interlocks. Plenty of diagrams online.