Slim shady
Member
formula please
3 phase unbalance resistive load delta formation
3 phase unbalance resistive load delta formation
You don't complex calculations,IMO. Count the good elements connected to each phase and balance your heater loads, if that's what you wanted. From your data above, you have thirteen elements per phase. Inspect and count the elements that are not busted and compare with other phase loads.there should be a total of 39 elements that should be installed
39 x 2500watts = 97.5kw of total heating
I believe the issue is that he can't determine the number of non working heater elements without shutting the machine down and taking it apart. He is looking for a way to determine the number of non working elements from the current that the equipment is pulling. That will permit him to order the new heaters without shutting the machine down.You don't complex calculations,IMO. Count the good elements connected to each phase and balance your heater loads, if that's what you wanted. From your data above, you have thirteen elements per phase. Inspect and count the elements that are not busted and compare with other phase loads.
rattus, pt, winnie -
Just curious - Do all heater elements burn out with age?
cf
I think your amp readings indicate your heaters have lots of blown-out elements! With 94.5 kW of heating at 390V, your line amps should be around 144.34 amps (balanced). Assuming your amp readings are correct:
Ia = 72 A; Ib = 51 A; Ic = 66 A
My computations tell me that your phase to phase heater loads are:
Lab = 12,944 (roughly 5 heaters working) - 8 elements busted
Lbc = 9,958 (4 heaters working) - 9 elements busted
Lca = 19,273 (8 heaters working) - 5 elements busted
Or a total of 42.17 kW (65% of rated heating power).
A total of 23 elements are for replacement.
I am using my own vectorial addition spreadsheet, so others can correct me.
Hope this helps.
Can you explain briefly how you went about this calculation. I understan(d) that it needs to be done vector(i)ally but dont know where to start considering there are probalby multiple combination with L-L heater loads that result in the given phase currents.