selecting the appropriate thermal overload relay for three phase asynchronous motor

[iswiss]

i have a mixer of breed floor run by a three phase asychnonous motor for which there is no nameplate .i measured the starting current(10A) and the nominal current (6A)
please help me to choose the right thermal overload relay for this
motor also the good brand name .
sincerly yours
mohamed riahi

 

[telectrix]

Re: selecting the appropriate thermal overload relay for three phase asynchronous mot

i would use an overload with variable setting say 8A - 15A or thereabouts. try it at the lower setting and increase if necessary.

 

[Marvo]

Re: selecting the appropriate thermal overload relay for three phase asynchronous mot

You usually size the protection to the run current, not the start current so maybe a 4-6A overload would be better. If you oversize it then it's possible for someone to come along in future and set it too high for it to be effective.

 

[Knobhead]

Re: selecting the appropriate thermal overload relay for three phase asynchronous mot

If you’ve measured the normal running current at 6A and the motor shows no sign of over heating, use this as the base for your selection. An overload with a range of 5 to 9A would suffice. I would recommend Telemecanique.
It’s difficult to make an accurate assessment / recommendation without the motor details.

 

[Knobhead]

Re: selecting the appropriate thermal overload relay for three phase asynchronous mot

It’s nice when an OP gets back with a reply, iswiss has just PM’ed me with thanks.