I have a motor of 12 leads, with low voltage and high voltage connections and at the same time with star and delta connections. My question is which is the best connection for the high voltage 460V is it star or delta connection?
460V, assuming you are in the US, is generally considered the High voltage, based on local standards being 230 or 460V.
Star or Delta is irrelevant here, you must just connect for whatever voltage you have and what the connection diagram says. The Star and Delta connections, as far as the US is concerned, is based only on using Star-Delta starting as a method of reducing inrush current (it rarely really does, but that's a different discussion).
If you permanently connect it in Star and apply 460V, you will decrease the effective voltage across the wndings by the square root of 3, or to 58% and thus reduce the output torque to 1/3. That then reduces the maximum allowable connected HP you can use without stalling the motor to 1/3 of what the motor is rated for. Some people think this will save energy if the motor is lightly loaded, but don't do it. Every time I have seen someone try ths it ends in the destruction of the motor. The amount of energy it saves is miniscule.
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In our industry 5 years before i have changed delta connection to star in 5 motors since the load in delta lesser than 50%. It saved energy and working ok.
delta & star connection
Re: delta & star connection
