SecondGen
June 16, 2020, 07:02 AM
Two loads are connected to the same source. Load 1: 1250KVA @ 0.85PF. Load 2: 600KW, 300KVAR. What is the combined load in KVA & PF?
Another user posted 1825.8kVA @ 0.91 PF in a different thread and I couldn't come up with this answer. Here is what I did:
Find combined PF:
1.) Using individual PF, calculate KW and KVAR of each load
2.) Add KW of each load to find combined KW
3.) Add KVAR of each load to find combined KVAR
4.) Combined PF is calculated as:
4a.) Tan0 = Combined KVAR / Combined KW
4b.) Combined PF = Cos (TanInv0)
1a) 1,062.5kW, 658.478kVAR = 1,250,000VA @ 0.85 PF
1b) 600kW, 300kVAR = 670,820VA @ 0.8944 PF
2.) Combined kW = 1,662,500 W
3.) Combined kVAR = 958,478 VAR
4a.) Tan0 = 958,478 / 1,662,500 = 0.5765281
4b.) Cos(TanInv0.5765281) = Cos(29.9646573) = 0.8663
Find kVA using combined values and A^2 + B^2 = C^2, then sqrt(C^2):
1.) 1662.500^2 = 2763906.25
2.) 958.478^2 = 918680.076484
3.) 2763906.25 + 918680.076484 = 3682586.326484
4.) sqrt(3682586.326484) = 1,919.006
Result: 1,919kVA @ 0.87PF
Can someone check my work and let me know if I'm doing something wrong? I was able to verify my combined values using this calculator: https://www.omnicalculator.com/physics/power-factor
Original thread: https://testguy.net/threads/5088-NETA-4-Exam-Questions-1-2017
Another user posted 1825.8kVA @ 0.91 PF in a different thread and I couldn't come up with this answer. Here is what I did:
Find combined PF:
1.) Using individual PF, calculate KW and KVAR of each load
2.) Add KW of each load to find combined KW
3.) Add KVAR of each load to find combined KVAR
4.) Combined PF is calculated as:
4a.) Tan0 = Combined KVAR / Combined KW
4b.) Combined PF = Cos (TanInv0)
1a) 1,062.5kW, 658.478kVAR = 1,250,000VA @ 0.85 PF
1b) 600kW, 300kVAR = 670,820VA @ 0.8944 PF
2.) Combined kW = 1,662,500 W
3.) Combined kVAR = 958,478 VAR
4a.) Tan0 = 958,478 / 1,662,500 = 0.5765281
4b.) Cos(TanInv0.5765281) = Cos(29.9646573) = 0.8663
Find kVA using combined values and A^2 + B^2 = C^2, then sqrt(C^2):
1.) 1662.500^2 = 2763906.25
2.) 958.478^2 = 918680.076484
3.) 2763906.25 + 918680.076484 = 3682586.326484
4.) sqrt(3682586.326484) = 1,919.006
Result: 1,919kVA @ 0.87PF
Can someone check my work and let me know if I'm doing something wrong? I was able to verify my combined values using this calculator: https://www.omnicalculator.com/physics/power-factor
Original thread: https://testguy.net/threads/5088-NETA-4-Exam-Questions-1-2017