3 phase motor help please
Discussion
Hi, I need advice (in simple terms) about an electrical problem.
I have an industrial mixer that has started cutting out at random times. The main drive is 3 phase 11 KW, 20 years old but only runs an hour or so a day.
Do these things tend to work or not work, or is it possible that general wear could cause random stopping?
Another problem (possibly related?) is that a couple of times recently the material being mixed has partially compacted in the mixer. When turning the main drive on, the blades don't turn and the fuses blow (old type ceramic holder with fuse wire) I'm using 35 A wire, is this too heavy, not heavy enough, or about right?
Forgive my ignorance, any advice greatly appreciated.
I have an industrial mixer that has started cutting out at random times. The main drive is 3 phase 11 KW, 20 years old but only runs an hour or so a day.
Do these things tend to work or not work, or is it possible that general wear could cause random stopping?
Another problem (possibly related?) is that a couple of times recently the material being mixed has partially compacted in the mixer. When turning the main drive on, the blades don't turn and the fuses blow (old type ceramic holder with fuse wire) I'm using 35 A wire, is this too heavy, not heavy enough, or about right?
Forgive my ignorance, any advice greatly appreciated.
thanks for the info. As said above, then, the fuses will be absolutely fine!Is it fed direct on line (star/delta possibly), by a soft start, or by a variable frequency drive (an "inverter") ?
To check the motor, remove all power, check if it is wired open ended to a star/delta setup, or is hard wired in either star or delta.
You will have three windings, they should all have equal resistance, then meggar them to earth, for a 415v motor, use at least a 1000v meggar.
Once you're satisfied the windings seem ok, check bearings etc, ( I've even come across motors with faulty bearings that will rotate freely in one direction, but be hard/impossible to turn in the other direction).
Once that is done, monitor the current on each phase using a "clip on", note it will need to be capable of reading variable frequency if you are using an inverter, as standard clip ons, for the uk market, will be setup to operate on 50Hz.
If the above doesn't make sense, leave it alone, and get somebody to check it for you.
If you need it checked for you, what part of the UK are you in ?
To check the motor, remove all power, check if it is wired open ended to a star/delta setup, or is hard wired in either star or delta.
You will have three windings, they should all have equal resistance, then meggar them to earth, for a 415v motor, use at least a 1000v meggar.
Once you're satisfied the windings seem ok, check bearings etc, ( I've even come across motors with faulty bearings that will rotate freely in one direction, but be hard/impossible to turn in the other direction).
Once that is done, monitor the current on each phase using a "clip on", note it will need to be capable of reading variable frequency if you are using an inverter, as standard clip ons, for the uk market, will be setup to operate on 50Hz.
If the above doesn't make sense, leave it alone, and get somebody to check it for you.
If you need it checked for you, what part of the UK are you in ?
Nigel Worc's said:
Is it fed direct on line (star/delta possibly), by a soft start, or by a variable frequency drive (an "inverter") ?
To check the motor, remove all power, check if it is wired open ended to a star/delta setup, or is hard wired in either star or delta.
You will have three windings, they should all have equal resistance, then meggar them to earth, for a 415v motor, use at least a 1000v meggar.
Once you're satisfied the windings seem ok, check bearings etc, ( I've even come across motors with faulty bearings that will rotate freely in one direction, but be hard/impossible to turn in the other direction).
Once that is done, monitor the current on each phase using a "clip on", note it will need to be capable of reading variable frequency if you are using an inverter, as standard clip ons, for the uk market, will be setup to operate on 50Hz.
If the above doesn't make sense, leave it alone, and get somebody to check it for you.
If you need it checked for you, what part of the UK are you in ?
I think fed direct but this only proves that I don't have a clue To check the motor, remove all power, check if it is wired open ended to a star/delta setup, or is hard wired in either star or delta.
You will have three windings, they should all have equal resistance, then meggar them to earth, for a 415v motor, use at least a 1000v meggar.
Once you're satisfied the windings seem ok, check bearings etc, ( I've even come across motors with faulty bearings that will rotate freely in one direction, but be hard/impossible to turn in the other direction).
Once that is done, monitor the current on each phase using a "clip on", note it will need to be capable of reading variable frequency if you are using an inverter, as standard clip ons, for the uk market, will be setup to operate on 50Hz.
If the above doesn't make sense, leave it alone, and get somebody to check it for you.
If you need it checked for you, what part of the UK are you in ?
Time to find a man that does have a clue. Glasgow based.
Thanks for your advice
db said:
I think fed direct but this only proves that I don't have a clue
Time to find a man that does have a clue. Glasgow based.
Thanks for your advice
I have a friend who is an onsite engineer in Greenock, (I may actually be coming up within the next week to look at some position controller issues he has), if you're stuck, I can ask him if he'll have a squint for you.Time to find a man that does have a clue. Glasgow based.
Thanks for your advice
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