380 VAC Induction Motor

<1.What cause three phase 380v AC induction motor burn?>

Too much current. The overload protection unit at the motor starter was set too high.

<2.How a solid state starter protect three phase 380v AC induction burn?>

The electronic overload needs to be set to the full load current of the motor. If it is set higher, then there is nothing to prevent a repeat occurrence.

First let me know few things

• Whethere this motor is earlier rewinded?
• what type of load connected to this motor, i.e. application?
• What is the voltage you are feeding to this motor through starter?
• What was the O/L set and what is the current drawn by the motor on load?
• what is the FLC of the motor?

probably with clarification of these points we can make out something

1. There are literally dozens, if not hundreds, of reasons why a motor may "burn", and even the term "burn" can mean a large number of things. Over current is the most likely, but certainly bad bearings, high harmonics, poor insulation, voltage spikes, high ambient heat, water intrusion etc etc etc are all valid.

2. Not all Solid State SStarters are the same, in fact some provide NO protection. That is a question only the manufacturer of the starter can answer.

1. Heat. This can be caused by:

(i) overloading or 'pushing' current by overvolting, effect is overall lacquer discolouring where heat is localised. Inadequate cooling or too high ambient temperature could also cause excess heat.

(ii) Winding insulation failure by shorting due to insulation breakdown and poor segregation/untidy arrangement in manufacturing causing short circuit.

2. As far as I know, this only provides motor load current protection and so if 1. is caused by overload it can help protect the motor

I had a this problem a few yrs ago and I installed a over-curnt potctor to stop the in rush of curent. Ther are systems avalble that can monator load and spiking.

Aaron

ht3captin@gmail.com

what is the stator connection. It must be delta .Most probable reason could be single phasing.

You will find some great explanations of motor failure modes available from Sprecher and Schuh including colour photos of damaged windings and why it happened. Try their website.

Solid state motor protection relays are used to protect motors more accurately than older means. Some solid state starters (softstarters or VSDs) incorporate this quality of protection some don't. Once again the S&S site will help. Also Google GE Multilin and Merlin Gerin Sepam.

Two phases shorted, depending on shorted to what is often due to single phasing.