need help

[aakash 0]

hi 

 We have heater which is feeding at set line speed (mm/sec)  by operator let say the weigh of one bar is 1080 grams The per unit cost is Rs 3.21.I need to create program to show the power consumption (cost per kg) at the Hmi . Some one have any ideas ,how i can do that .

 

Regards

 

[Luke.S 8]

Do you mean 1kWh of electricity to power the heater costs Rs3.21?

If it's an electric heater you could measure the current to it with a current transducer on the line, feed that back to the PLC analog input and get a wattage with P=IV.

Then if you know the length of the oven you know how long the product was in there: time(s)=length of oven(mm)/speed(mm/s). From that you can get calculate how much of a kWh was used on one product.

[aakash 0]

hi

yes 1kwh costs 3.2 approx but actually its voltage fed it usually calculates the current required for heating up a required bar or we can change the current value depending on need .What i require is the hmi to show the per hour consumption (cost per kg)  every time and it will be changing as the line speed is changed , what confusing is that if i am calculating the per hour consumption will it be showing once per hour  or all the time every second or minute?

[Luke.S 8]

Perhaps I should point out that strictly speaking this topic probably shouldn't be in the Mitsubishi board.

But anyway, if you are adjusting the line speed to make each product get enough heating time then maybe you could just average out the current consumption of the heaters over a certain period. That'll give you the average kW usage. A kW just means 1000J/s and  1 kWh =3,600,000 J.

So for example if the heater is using an average 1 kW and the product is in the oven 10 seconds at the current line speed then current cost per product is (10,000 J/3,600,000 J)*3.21Rs.

You could display it in real time based on real time line speed feedback. Cost_PV=(((oven_length/lineSpeed_PV)*averagekW_PV)/3,600,000)*3.21

If you want it per kg then just divide that cost by the weight of the product. I am assuming that only one product goes through the oven at a time, otherwise it's a bit more complicated but that's the general idea.

[aakash 0]

thanks a lot. well at a time there are around 30 approx bars .