Example of line voltage drop in a three-phase motor – please explain
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For a 90KW three-phase asynchronous motor, using 70 square millimeter copper cables over a length of 600 meters, with a constant power factor of 0.85 and a voltage of 380V, what are the line voltage drops when the motor is connected in star configuration and in delta configuration respectively? Rated current: I_phase = 161A, I_star = 93A ； Resistance calculation: R=ρ×L/S=0.15Ω ； ρ=1.75*10-8, L=600m, S=70mm2 ； (1) In star connection: U_drop = 13.95 V. (2) In delta connection: U_drop = 24.15 V. Questions: 1. In star connection, what is the voltage drop ratio? Is it a = U_drop/220 V = 6.34% or a = U_drop/380 V = 3.67%? 2. In delta connection, when calculating the voltage drop as the drop across one of the phase wires, why isn’t the formula a = 1.732*U_drop/380 V = 11% used, but rather a = U_drop/380 V = 6.36%? I’m not sure about these two questions; please advise me, thank you
For copper-core cables with PVC insulation and a cross-sectional area of 70 square millimeters, the voltage loss rates at power factors of 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 are 0.097, 0.109, 0.120, 0.111, 0.125, and 0.139 respectively (%/A.km)
Hello, could you explain it in detail using my example? Thank you.