Need Help with Breaker Sizing 3 phase

[Yuri Lapidario]

Good day to all. Please correct me if im wrong and also want your professional inputs.
I am servicing a pump motor rated at 415vac 3 phase 11kw power. The breaker is at 20amperes. The complain is everytime the motor automatically stop when the tank is full the breaker always trip during the motor's initial run. When i checked the start up current the reading is around 40amperes. But during nkrmal run the reading is only 20 amperes.
So is it because the starting current is high that is why the breaker trip?
Now i changed the breaker with 32 ampere rating and see what happens.
Your advice is highly appreciated.
Thanks

 

[Pete999]

Good day to all. Please correct me if im wrong and also want your professional inputs.
I am servicing a pump motor rated at 415vac 3 phase 11kw power. The breaker is at 20amperes. The complain is everytime the motor automatically stop when the tank is full the breaker always trip during the motor's initial run. When i checked the start up current the reading is around 40amperes. But during nkrmal run the reading is only 20 amperes.
So is it because the starting current is high that is why the breaker trip?
Now i changed the breaker with 32 ampere rating and see what happens.
Your advice is highly appreciated.
Thanks

What type of CB is it B,C,D, etc?

 

[Pete999]

What type of CB is it B,C,D, etc?

Tend to agree with you Murdoch,

 

[Yuri Lapidario]

I cant paste the picture here but its a scneider brand with adjustable ampere rating from 24 to 32. Now i set it to 32 because previously i saw it in 24

 

[Pete999]

I cant paste the picture here but its a scneider brand with adjustable ampere rating from 24 to 32. Now i set it to 32 because previously i saw it in 24

OK might be able to see what type it is from your pic.

 

[westward10]

Sounds like a 947-2 mccb.

 

[Yuri Lapidario]

This is what im talking about....

 

[Yuri Lapidario]

 

[westward10]

That is a thermal motor circuit breaker. Is this a recent installation or has it been operating okay in the past.

 

[Yuri Lapidario]

Yeah a recent installation from the other person just endorsed to me. Now i am the one handling this and their common complain is frequent trip of this breaker after every automatic shutoff from the level sensor of water tank.
This is the breaker going to soft starting relay then going to 11kw 415v 3 phase pump motor

 

[westward10]

And it has done this from the point of installation.

 

[Pete999]

Yeah a recent installation from the other person just endorsed to me. Now i am the one handling this and their common complain is frequent trip of this breaker after every automatic shutoff from the level sensor of water tank.
This is the breaker going to soft starting relay then going to 11kw 415v 3 phase pump motor

Have you spoken to Schneider technical for advice?

 

[westward10]

An 11kw motor on 415v should have a flc of 20 to 23A so with breaker set to minimum any load on the motor will result in a trip.

 

[Yuri Lapidario]

So you mean im doing the right thing, i increase the setting from 20amps to 32 amps.

 

[Darkwood]

That is a motor overcurrent protective device, it is designed to be set to the flc of the motor if DOL, as it starts at 24 I can hazzard a guess for an 11kw motor this will be about the setting, the motor plate will tell you what rating it should be set to, the soft start should limit inrush.
What is the duty of the motor?, what is the duty allowance of the soft start?, is that the device tripping in the picture?

Turning this overload up is not the way to resolve this, you need to know what is causing the tripping and why, if it is a poor design or a fault then increasing the overload setting may cause bigger problems and could damage the motor and any risks associated with that.

My final question and may change how we reply to your posts is -

What is your electrical background, experience and qualifications ?... my concern is with not recognising a motor overload trip and another thread asking about CCC of a cable it thus raises concerns about the work you are doing here.

 

[Yuri Lapidario]

Honestly my background is electronics with some experience in electricals but no formal electrical study. I am assigned on plc controlled machines but since our electrical guy resigned and my boss is cutting expenses by hiring another person she want me to take over electrical job.
Maybe you can give me some helpful sites that i can read.
Because what we have is a motor pump to transfer water to other tanks.

 

[Darkwood]

Fully appreciate your honesty in your position and you have my sympathies if that is the position you have been put in, I must add that the forum has to be seen to give both safe and correct advice for members relative to the experience, training and position they hold, it is clear you are undertaking work out of your field through no fault of your own and unfortunately we do not allow step by step guides especially in this sector of the industry.
I cannot advice of any other forum that would be willing to advice you as we all tend to follow similar rules, I think you need to be honest with your boss but given your origin I can understand if this is not an option but as I have stated before, we have safe advice as a priority and that would be in your case to get a competent person in, may I stress this is no dig at your competence in your own field, it seems you are obviously been asked to undertake work that is out of your training and experience so with all respect to your position I am only left with the option to close the threads you posted.