The hummmm reminds me of something else entirely.
David Best
https://www.instagram.com/davidpbest/
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On Dec 17, 2020, at 10:10 PM, David Kumm <
davekumm@...> wrote:
The hum reminds me to turn it off and to be really careful.? High voltage is scary.? I had a 600v machine and spent a lot of money to convert it as all the controls were 600 as well and I'm absent minded and clumsy.? Dave
Buying a transformer is the easy option but I hate hate hate 60hz hum and I¡¯ve never been around a transformer this size that didn¡¯t hum
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Joe, if that machine can be run on low voltage, you may need to boost your voltage.? 277v less 10% brings you down to the 250v minimum.? the motors will likely run warmer and may be fine but is it easy and cheap to
put two? buck boost 32v transformers, wired open delta on the machine to get within spec.? I did this with my Robinson.? Two 1 kva transformers handles a 7.5 hp motor.? I bet the motor is wired 480 so looking at the starter will tell you how complicated it
is to swap that for the lower voltage.? If you step up to 480, the preferred transformer would be a three phase 240 delta to 480 wye step up isolation unit.? Some transformers can be run in reverse but you need to understand the grounding issues when doing
so.? Generally if the plate on the transformer says " low and High " you shouldn't reverse.? If it says " primary and secondary" it may be OK but should be checked by the manufacturer.? An auto transformer will be delta to delta in your case and be a smaller
unit and cheaper but may not deliver quite as clean power as an isolation transformer.? Clean is my layman's term and not technically correct.? Lots of machines run fine with an autotransformer but they are more often used when the voltage spread is less.?
Buck boost transformers are autotransformers.
Let us know what you find.? Dave
Here is the power service I have, listed on websites as ¡°Uncommon¡±
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Joe,
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I am pretty sure both motor labels say they are 250-277V when delta connected and 440-480V when Y connected ¨C (60 Hz).
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Do you see a pictorial that shows how to connect motor leads for delta power?
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I am not knowledgeable enough to know if 230V that you have is okay for the 250V min rating on the motor plate.
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Imran
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The Langzauner sander machine tag says 3 phase 460V.? The specs in the manual say 400V 3 phase. ?The power junction box on the machine is labeled 480V, looks like this
is from the last shop.? Ideally I can rewire for 240V three phase.? My power supply is utility Delta 230V 3 Phase.
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Machine tag, and two motor tags pics attached.? I¡¯m and electrical engineer who has been a business person for 25 years so I¡¯m not fluent in this stuff today.? Looks like
at least these two motors can run in the 250V range.? Does the tag specify delta power?? I see some step up transformers are 240V Delta 2 phase in and 480V WYE out.?
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I don¡¯t yet have it off the pallet to check the other bits.?
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David P. Best