immensity725
Member
- Location
- reading, pa
what would be a good manual motor starter for a single phase,3hp, 230v motor with a fla of 16 amps. I'm using a 35 amp breaker with a 25 amp time delay fusible fuse...the motor is for an exhaust fan...
inquire on overload protection
- Thread starter immensity725
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- Licensed Electrician
What does your boss or journeyman say to use?
1ph? Have you confirmed that the motor has integral internal overload protection already? If so it's a done deal as far as motor overload protection. Then it's a matter of sizing the wire correctly to carry the load and then protecting the wire with a correctly sized OCPD the way that I see it.
immensity725
Member
- Location
- reading, pa
It does not come with a internal heater..
kwired
Electron manager
- Location
- NE Nebraska
Same type of devices used for three phase motors work here - plus you only need a single pole unit - all current coming in one line has to leave the other line if the motor is free of ground faults.
Sometimes you see three pole units with phase loss protection used - in that case one line usually goes straight through, the other line is run in series through the other two poles - otherwise phase loss protection will trip if only two poles are loaded.
Sometimes you see three pole units with phase loss protection used - in that case one line usually goes straight through, the other line is run in series through the other two poles - otherwise phase loss protection will trip if only two poles are loaded.
You mean integrated overload protection (a temperature-sensing switch is a common means).
An internal heater really is just a heater.
You will find what you need here http://www.eaton.com/ecm/idcplg?Idc...veAs=0&Rendition=Primary&dDocName=VOL05_TAB03
http://www.eaton.com/ecm/idcplg?Idc...veAs=0&Rendition=Primary&dDocName=VOL05_TAB03
pg 11
Eaton calls them heaters
common terminology
In a starter, and when a part of a bi-metal overload switch (not the electronic OL's).
Temperature-sensing switches integral with the motor are similar... but they are simply not called heaters, at least not in my neck of the woods... and relatively speaking, that's not all that far from yours.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
:thumbsup:
The bimetal is calibrated to a particular temperature, and has no direct way to measure the current in the motor, unlike the magnetic trip in a breaker.
So the bimetal is heated by a carefully chosen series resistance, lower for a higher set point, higher for a lower set point.
So the basic overload mechanism has a range of trip values and where in that range the actual trip point falls depends literally on what heater you add to it.
Thanks for the respond. Then consider a combination motor starter selecting the correct overload relay heaters for the motor FLAs. The OLR responds to motor load and the breaker disconnect most likely using a correctly adjusted motor circuit protector, MCP, protects the contactor and circuit with short circuit protection should there be a motor winding failure. If done correctly you will be able to provide coordinated protection.
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