motor start / stop damages?
motor start / stop damages?
(OP)
Hello all,
We have a lot of 3 phase induction motors at our facility and some people think they may save energy by turning on and off those motors 3-4 times an hour. For the past few weeks I have been trying to find some good information on how often a 3 phase induction motor can start and stop per hour or day before it starts to sustain serious damage. I know that its probably different for different manufacturer, but it would be nice to have a bulk part and maybe links to different articles talking about the effect of doing so. Personnally I think the savings far outpast the damages and reduced life of the motors that will eventually result from those frequent start and stop, even with a soft start? Correct me if I am wrong. Thanks guys!
We have a lot of 3 phase induction motors at our facility and some people think they may save energy by turning on and off those motors 3-4 times an hour. For the past few weeks I have been trying to find some good information on how often a 3 phase induction motor can start and stop per hour or day before it starts to sustain serious damage. I know that its probably different for different manufacturer, but it would be nice to have a bulk part and maybe links to different articles talking about the effect of doing so. Personnally I think the savings far outpast the damages and reduced life of the motors that will eventually result from those frequent start and stop, even with a soft start? Correct me if I am wrong. Thanks guys!





RE: motor start / stop damages?
This topic was well covered about a week ago.
See thread237-152831
yours
RE: motor start / stop damages?
ht
There was a mention of 5 minutes off-time => secure a motor as I understood it. I think it may work in some circumstances but tough to generalize. As motors get larger and faster and carry higher inertia the limits get more restrictive.
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RE: motor start / stop damages?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: motor start / stop damages?
RE: motor start / stop damages?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: motor start / stop damages?
RE: motor start / stop damages?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: motor start / stop damages?
RE: motor start / stop damages?
The power needed for continuos one direction motion was 5HP I installed a 15 HP motor and am using direct contactor starting with no power reduction. It has been working for a couple of months and no problems up to now except we fried the thermal protector (set it to low to protect the windings and we have replaced it with 2 sets in series of thermal overload protectors, if any one trips all the system stops.
Regards
SACEM1
RE: motor start / stop damages?
You may want to consider switching to a solid state thermal overload relay. The stresses on bimetal or melting alloy relay elements are probably what are causing your repeated failures.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: motor start / stop damages?
Regards
SACEM1
RE: motor start / stop damages?
Solid state thermals are so, SO much better! Truly superior!
Most motor starter makers have them that fit right in place of the damn bi-metal/melting pieces of junk. So do inquire for your make!
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: motor start / stop damages?
Siemens make one specific design in their 3RB10 range which covers the 50 - 200A range, which covers the majority of the LV drives which I deal with, and certainly the ones we have most trouble with. My site has a lot of starters which are one module size too small for the starter they are housing, so heat is our big enemy: we've had good results using these overloads - less starter problems and less dead motors. It's the S6 frame size on the following link:
h
Big file - probably not worth it if you're on dialup!
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I don't suffer from insanity. I enjoy it...
RE: motor start / stop damages?
h
you may have to cut/paste this link as I see pesky '?'.
http:
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: motor start / stop damages?
the poles (for D.C. motors - 2 at one setting and
2 at another)? Sounds like just the ticket for
replacing some existing overloads - some folks
here are using 3-pole start/stop contactors with
one side of the field run thru the contactor and
smaller heater, and the other side of the field
run thru an auxilliary.
<als>
RE: motor start / stop damages?
Eng-Tips: Help for your job, not for your homework Read FAQ731-376