Setting Motor Overload

[MikeGore]

Hi,

How do you set a motor overload? I have read that you set it at the FLA of the motor but also that you should consider service factor. Which is correct? Thanks.

 

[Megawatt]

Hi,

How do you set a motor overload? I have read that you set it at the FLA of the motor but also that you should consider service factor. Which is correct? Thanks.

Mike if the service factor is 1.15 you take the FLA times 125% and that’s the amperage you set your overloads. What is the service factor
[automerge]1568308840[/automerge]

Mike if the service factor is 1.15 you take the FLA times 125% and that’s the amperage you set your overloads. What is the service factor

All other motors are 115% times the FLA

 

[Strima]

Single or three phase?

Motor rating? (Kw)

Power factor?

Etc etc etc

 

[Carl S]

Mike if the service factor is 1.15 you take the FLA times 125% and that’s the amperage you set your overloads. What is the service factor
[automerge]1568308840[/automerge]

All other motors are 115% times the FLA

In the US with Nema starters maybe.

Here you set the O/L to the FLC unless your working in a museum with dashpot overloads. Modern thermal O/L’s take in to account transient over current.

 

[Megawatt]

Single or three phase?

Motor rating? (Kw)

Power factor?

Etc etc etc

Stroma I believe he left

In the US with Nema starters maybe.

Here you set the O/L to the FLC unless your working in a museum with dashpot overloads. Modern thermal O/L’s take in to account transient over current.

Carl he asked a simple question and I gave him a simple answer

 

[Carl S]

Carl he asked a simple question and I gave him a simple answer

But the wrong answer for the UK

 

[Megawatt]

But the wrong answer for the UK

Carl I should have stated that in the USA, NEC article 430-22

 

[Pete999]

Single or three phase?

Motor rating? (Kw)

Power factor?

Etc etc etc

Stop confusing the OP Strima, no wonder he did a runner
[automerge]1568312503[/automerge]

Stop confusing the OP Strima, no wonder he did a runner

Apologies OP I didn't note you were a trainee. Perhaps if you had worded your question a bit better with more background people might have shown some sympathy, me included.

 

[MikeGore]

Ok thanks for all your replies! It looks like the answer is different in the US and UK then?

I don't have a specific motor that I am working with, I am just looking to understand how to set one for each situation really. I really want to learn and have a lot of questions that don't get answered at work. I have been unluckily working with people who aren't that interesting in sharing their knowledge (or probably don't actually know).

So in the UK we can just set it to the FLA of the motor but in the US you have to take in to consideration the service factor? Is that correct? What about the other things mentioned above, power factor and Kw's etc?

Also now I'm wondering why its different in the US from the UK? Anyone know?

 

[Megawatt]

Ok thanks for all your replies! It looks like the answer is different in the US and UK then?

I don't have a specific motor that I am working with, I am just looking to understand how to set one for each situation really. I really want to learn and have a lot of questions that don't get answered at work. I have been unluckily working with people who aren't that interesting in sharing their knowledge (or probably don't actually know).

So in the UK we can just set it to the FLA of the motor but in the US you have to take in to consideration the service factor? Is that correct? What about the other things mentioned above, power factor and Kw's etc?

Also now I'm wondering why its different in the US from the UK? Anyone know?

Mike Yes on service factors and instead of KW on motors we use the HP but there are so many motors out there and yes 3 phase or single phase makes a difference. Also there is a huge difference between the UK and US with the difference in voltages and calculations, services to homes are a whole lot different. If you want to learn the USA standards go on line and get you a NEC 2020 edition if it’s come out yet. We change every 3 years so you could get 2017 edition. Welcome