How to Size an Overload Device for a Motor

In this video, Keith will walk you through the calculations necessary to size overload devices for motors. We'll go over external and internal overload devices such as starters, overload relays and VFDs.
Check this video out if you have been looking for a solution to your motor overload problems. If you don't know how to install or where to buy overload protection devices check this video out and click the links in the description. If you are looking to calculate your electrical overload rating for your motors this video may also interest you.
And if you ever wanted to see a motor light on fire, check out 5:42!
Buy an overload protection device: www.emotorsdirect.ca/controls
Contact us: www.emotorsdirect.ca/contact-us
Supporting articles:
www.emotorsdirect.ca/knowledg... www.emotorsdirect.ca/knowledg...
www.emotorsdirect.ca/knowledg...
0:00 Introduction
0:53 Recap On Motor Overload 1:38 External Overload Devices
1:40 Overload Relays & Starters
2:08 VFDs
2:23 Internal Overload Devices
2:41 Electrical Rating Calculations
5:42 Motor Overload Time Lapse
5:55 Conclusion
Formulas:
If service factor is greater than or equal to 1.15, multiply the FLA by 1.25
If service factor is less than 1.15, multiply the FLA by 1.15
If SF is unknown, multiply the FLA by 1.15 FLA * 1.15 = X amps
OR
FLA * 1.25 = X amps
The maximum setting or rating for the overload protection device is X amps.
In cases where your electric motor setup has reduced voltage starting, specifically in wye/delta start motors, the max overload setting will be calculated based on the phase current and not on the line current. The motor starts in the wye configuration and then switches to the delta configuration once the motor gets up to speed. The current draw is different in each configuration, so the max overload will be set based on the phase current. This means that you have one additional calculation to complete before you can calculate the max overload setting. You will use the line current to calculate the phase current. Phase current is about 57.7% of the line current.
In wye/delta start motors: FLA * 0.577 = X X * 1.15 = Y amps The maximum setting or rating for the overload protection device is Y amps.

[@that1electrician]

I can see this channel blowing up real quick just like realPars did.
I can sense it. Great quality videos and great information. Must watch for any industrial maintenance technicians, tradesmen, apprentices, and the youngins still in school!

[@emotorsdirect]

Thanks for supporting our videos @that1electrician! It sounds like you do maintenance on motors often?

[@gabrielwilson6075]

Thank you very very much.i will die with your page.Great information Sir.Thanks

[@emotorsdirect]

Thanks Gabriel, please don't die 👍

[@jordaoantonio808]

thank you sir, I learned a lot from this video and i will be beyond grateful if you also cover "Ct operated Relay"

[@emotorsdirect]

Hi Jordan - glad this was helpful! Yes, I'll add this topic to my list.

[@k.y22]

Thank a lot great information

[@emotorsdirect]

Glad it was helpful!

[@kurikoweiber5926]

awesome vid!

[@emotorsdirect]

Thanks Kuriko!

[@joeylaba]

A Correction is needed at 3:10. A Motor with a Service Factor of 1.15 Can be overloaded by 125% not 115%.

[@emotorsdirect]

Good catch! Edit made - thanks for the feedback.

[@HamedAdefuwa]

Im enjoying these

[@emotorsdirect]

Thanks Hamed - new videos coming soon

[@winner1338]

Very interesting channel, but if you could add some graphics like Realpars it will be top notch.

[@emotorsdirect]

I'll check out their page - thanks for the suggestion.

[@k.w.pubudu4520]

thanks a lot , sir can you explain if its use 2 overlords for star delta configuration is that wrong or is that reliable for safe conditions of a motor

[@emotorsdirect]

I see no reason to use more than one overload block as any one of them tripping will shut off power.

[@k.w.pubudu4520]

once i have experienced a motor getting damaged because of the timer problem, i think that kind of problem will not be affected after applying 2 overloads....I don't know if it's a better idea or not...once again thanks for your reply and its great work you are doing with this channel 👍👍

[@emotorsdirect]

@@k.w.pubudu4520 interesting! Thanks for watching. More videos coming in the next week or two.

[@gunaseelan9278]

Hi Keith , can I know your email id please ….I want to discuss more further about over load calculation

[@emotorsdirect]

Hi Guna, you can reach our team at [e-mail].