- Thread starter Shox Dr
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not done it yet
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Except that the dummies quote differing voltages, not different formats (star and delta).
There is bound to be someone that comes across a 400V delta wound motor, which will obviously never be converted to delta at 240V.
There is bound to be someone that comes across a 400V delta wound motor, which will obviously never be converted to delta at 240V.
Guineafowl
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This is what you should see in the connection box:
Hopefuldave
Intergalactic pot-mender
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True, one of the motors in my RPC is 400v delta, 700v star. But I don't need a neutral for the machines, all 400v 3-phase, if I ever should the other RPC motor (2.2kw) provides a neutral anyway, being 415 star. They're all "floating" thanks to an isolating transformer (I'm a big fan of safety isolation) but Motor2's star point could be earthed if I needed to?
Dave H. (the other one)
Shox Dr
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Aaaaaaand that's why I posted the diagram.
(Because I didn't understand a fecking word you wrote, Dave
. Pixies, I tell thee
)
sako243
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Bear in mind that you're not changing the resistance of the windings by doing that simple rewiring so by dropping the voltage to 220V without any control (for example a VFD) then it'll still try and pull a huge current on start-up.
Big 3 phase motors are often started in star then switched over to delta once up to speed. The star configuration puts two windings in series therefore doubling the resistance and reducing inrush current. Once the motors up to speed then contactors are used to switch over to delta windings so that you can get more power out of the motor.
Used a lot on guillotines, press brakes etc., where the motor is directly attached to a hydraulic pump.
Big 3 phase motors are often started in star then switched over to delta once up to speed. The star configuration puts two windings in series therefore doubling the resistance and reducing inrush current. Once the motors up to speed then contactors are used to switch over to delta windings so that you can get more power out of the motor.
Used a lot on guillotines, press brakes etc., where the motor is directly attached to a hydraulic pump.
doubleboost
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Hopefuldave
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Aaaaaaand that's why I posted the diagram.
(Because I didn't understand a fecking word you wrote, Dave
Not just Pixies, Pixies with Magic Smoke.... Kill the Pixie and the Magic Smoke escapes, never to be put back.
Dave H. (the other one)
Generators have the Star Point (Neutral) linked to Earth. Its to prevent the potential for a floating voltage between N & E, and resultant tripping of Distribution Load Earth Leakage Devices.
On that basis, I can't see why you couldn't do likewise on the motor as you stated.
(On 1ph Delta configured alternators - the Delta point selected as the Neutral is also linked to Earth for the same purpose).
