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weli13-Aquamarine
13-Aquamarine
July 23, 2018
Solved

Why OEE is zero?

  • July 23, 2018
  • 1 reply
  • 5045 views

Hi Experts,

I configured my demo asset as the following

Untitled.png

1.png

My KPI Calculation Period is 1 minute.

But my OEE,Quality and Performance are all 0

2.png

 

Can anybody tell me why OEE is always 0? I don't understand what's the problem.

 

Thanks & Best Regards

Tom

Best answer by mthakker

That's a good question, and has to do with how we handle rollover.  Because counters don't have infinite space, and may be reset at one time or another, we save a valuestream of the current good count and bad count.  When the counter drops below the previous number, we assume it rolled back to zero and then continued counting up.

 

Essentially what's happening is every time it drops down, this happens:

Drops from 800 -> 799

System thinks made 800 before, reset to zero, and then made 799

799 parts in the last X period of time -> feed it into the calculation.

 

Does that make sense?

1 reply

H
hchanana16-Pearl
16-Pearl
July 27, 2018

Greetings @weli,

 

OEE is calculated based on Availability, Quality  and Performance

The quality and performance are calculated as :

 

Quality = Good Count / Total Count

Performance = (Total Count / Run Time) / Ideal Run Rate

 

From the screenshot I can see that you manually entered Good Count and Total Count in Parameters for Performance Calculations. Can you browse tags for Good Count and Total Count from the Kepserver for this asset instead of providing manual values.

 

You can refer https://community.ptc.com/t5/Manufacturing-Apps/0-Performance-at-times/m-p/520717 community thread for detailed information on OEE and other KPI calculations.

 

Thanks,

Himanshu

W
weli13-AquamarineAuthor
13-Aquamarine
July 27, 2018

Hi Himanshu,

 

Thanks for your help.

Before I stared this topic, I already read the post you mentioned, and I read the document of how to calculate OEE, but I still don't understand why my OEE is zero. my understanding is:

my good count is 1,and total count is 1,so my quality should be 100%,

Performance=(Total Count / Run Time) / Ideal Run Rate , so at least my performance should not be 0,and since

OEE = Availability * Performance * Quality, my OEE should never be 0.

 

 

Thanks & Best Regards

Tom

V
vxavier5-Regular Member
5-Regular Member
July 27, 2018

In run time your total count will variate. The total count in this time will be the difference of the old total count and the new total count. If there is no differentiate it will no calculate. At last this is the way that I view it.

 

About quality I am not sure, but maybe the same things go for it, it has to be a value that changes on time. 

 

Please someone correct me if I am wrong.

 

You can Override this calculations also to best fit your tags and the way that the company calculates OEE. 

 

Hope it helps,

Vinicius Xavier.

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