mstrlucky74
Senior Member
- Location
- NJ
Is it true you don’t need neutral for 3 phase motors?
Motor Neutral
- Thread starter mstrlucky74
- Start date
- Status
- Occupation
- Licensed Electrician
All you need for a three phase motor is three phases. You don't need a neutral.
drktmplr12
Senior Member
- Location
- South Florida
- Occupation
- Electrical Engineer
true.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
the motor does not care.
broadgage
Senior Member
- Location
- London, England
Correct, no standard type of the three phase motor needs a neutral. If the motor is wired in Y then no external connection should be made to this point.
Be aware however that many motor control panels DO need a neutral connection in order to power relays, contactors and other ancillary equipment.
Likewise many machines that incorporate a 3 phase motor DO need a neutral, not for the motor itself but for ancillary equipment.
Be aware however that many motor control panels DO need a neutral connection in order to power relays, contactors and other ancillary equipment.
Likewise many machines that incorporate a 3 phase motor DO need a neutral, not for the motor itself but for ancillary equipment.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
To be clear, by “large”, he means typically 2,000HP and up, medium voltage motors. Not something the average electrician will come across very often in their career and when they do, it will likely be in a detailed engineered project with clear drawings and specifications telling you exactly what to do. People only implement differential protection on very high value assets where high speed detection of winding faults can mean the difference between thousands of dollars in down time versus millions.
Hey I resemble that remark about large motors. Our shop tops out at rebuilding them up to around 25,000 HP including the clean room for the 11 kV stuff. Big toys are fun until they break.
I’ve only seen differential motor protection once in a plywood plant in South Carolina. It was 4160 but it was only around 500-800 HP. The whole arrangement was goofy. Probably a contract engineer design if I ever saw one.
About the only thing you might save with differential protection is maybe, and this is a stretch, maybe core steel losses. A 2000 HP motor is still going to cost around a million give or take to rewind but could be triple that if the core has to be restocked.
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I’ve only seen differential motor protection once in a plywood plant in South Carolina. It was 4160 but it was only around 500-800 HP. The whole arrangement was goofy. Probably a contract engineer design if I ever saw one.
About the only thing you might save with differential protection is maybe, and this is a stretch, maybe core steel losses. A 2000 HP motor is still going to cost around a million give or take to rewind but could be triple that if the core has to be restocked.
Sent from my iPhone using Tapatalk
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