Calculating Average Consumption

Hi

I am currently working on a system that automatically tops up the oil level of a generator using a level sensor and I would like to calculate the average oil consumption when the generator is running

I have a pulse flow meter input to the PLC, and a pressure switch to tell the PLC if the generator is running, but I am looking for a solution to calculating the average consumption per 24 hours running.

Any help would be greatly appreciated

Currently using TIA V15.1 update 3

PLC is an S7-1200 6ES7 212-1BE40-0XB0

HMI is a KTP700 6AV2 123-2GB03-0AX0

Best Regards

Hi there,

• oil level gives you nothing;
• flow meter (with pulses at output) is OK. However you need to find exact place for that device;
• then calibration part (it needs to know exact quantity of fuel per, say, 100 or 1000 pulses);
• also may be significant temperature and viskosity factors;

Roughly:

• first try to get changing flow meter's value in Data Block;
• simple calculation  where e.g. 10 pulses = 0,85L ;  you've got  11250 pulses/ per hour;
• 11250pulses * 0,085L = 956,25L per hour;
  
•  956,25 + 890,30 ... +765,44 / 24 hours = average fuel consuption per 24 hours.
  

BR

Hi HBCM

thanks for the reply,

the level sensor is a ultra sonic type sensor and I use it to help control the level of oil in the generator, the high and low set points are set in the HMI and when the level drops below the set point the pump will start to pump oil to the generator, the pump will continue to run until the level reaches the high set point, at this point the pump will turn off. if I do it this way I don't need to calibrate tank volumes.

only I need to count the pulses and calculate the average consumption when the generator is running.

Regards

Desert Monkey

Desert Monkey

only I need to count the pulses and calculate the average consumption when the generator is running.

Regards

Desert Monkey

Forget about tank level system!

All what I've written above was about flow meter only! Read carefully.

BR

Hello.

Let me put in my two cents here.

be sure if module that is selected for counting (I don't think you have profinet flow-meter device) ensures a proper work with a certain pulses frequency. Otherwise you are in jam.

Msorich

Hello

I don't know the details of the pulse flow meter, it might be usable to measure the total oil usage.

But if it can't be used, you could also perform the following actions:

Measure the amount of oil that will be added to the generator. Find a formula for it and let your software do the measurement. For example, oil level sensor value is 5000 before oil gets added and the oil adding stops when sensor value is 10000. This equals to oil height 20cm and 60cm in a barrel whose area is 50cm^2. You can probably calculate the area of the oil container and then use the sensor difference to let software calculate the volume of added oil, once you know how the sensor values translate to oil levels. Then store the variable containing the volume for added oil.

Then you need to measure the total runtime of your generator from the last top up to before the generator needs to be topped up with oil again. The runtime measurement won't be an issue, you can use the RUNTIME command together with the rising edge of pump starting and falling edge of pump going off to measure how long the generator was active and then add this time to a combined time pool. (Reset the times when oil gets topped).

With these steps you will get two variables:

1) The amount of oil that was last added to the tank.

2) Amount of generator runtime needed before oil again needed to be added.

You can calculate the consumption with these variables.

The program would not be perfect, these would be the problems:

- If the topping up limits are modified, the calculations will be based on the new values and will give incorrect reults. Perhaps take the new values to use only during the next top up time?
- If the generator is running during the top up, this will not be measured, or depends on how it's measured, it might give faults to results.
- If the oil container is irregularly shaped, this approach won't work well. You could have quite complex formula for the calculation of oil volume though, so it might work.
- The consumption is only available after the oil has been topped up once.

Hope this gave you some ideas at least! And remember, there are multiple ways to do this, it might be that your flow meter is everything you need.

HBCM_ and OPisOm!

Look, later there will be some materialistic people here, which will start crying that such kind of help usually costs money. And that the original poster nothing did by yourself, just collects solutions.

Msorich

OT 

Msorich

Look, later there will be some materialistic people here, which will start crying that such kind of help usually costs money. And that the original poster nothing did by yourself, just collects solutions.

Or maybe those people really care that some individuals without basic knowledge and understanding of such simple things like e.g. a scan positive signal edge operand - a sneaky beast, which is always so challenging - finally learnt anything. Of course it's not obligatory.

Same as giving help to such individuals is not obligatory.