ℹ️ About This Calculator
A traction lift is counterbalanced, so its motor only has to lift the unbalanced part of the load, not the full car. This calculator estimates the required motor power in kW and the full-load current at 415 V from the rated load, rated speed, counterweight balancing factor and drive efficiency.
The counterweight is usually set to balance the car plus 40-50% of rated load, so a fully loaded or empty car presents the greatest unbalanced mass. Power scales directly with speed, so high-speed lifts need proportionally larger motors and drives. This is a preliminary estimate; the lift manufacturer's duty-cycle and starts-per-hour data governs the final selection.
📐 Elevator Motor Power Formula
IS 14665
P = (m × (1 − b) × g × v) / η I = P / (√3 × V × pf) P = motor input power, W m = rated car load, kg b = balancing factor (0.4-0.5 typical) g = 9.81 m/s² v = rated speed, m/s η = drive + gear efficiency I = full-load current, A; V = 415 V, pf = 0.85
🧮 Worked Example
Example: A 1000 kg lift travels at 1.5 m/s with a 50% balancing factor and 75% drive efficiency. Unbalanced mass = 500 kg, so mechanical power = 500 × 9.81 × 1.5 / 1000 = 7.36 kW, and motor input = 7.36 / 0.75 ≈ 9.81 kW. Full-load current = 9810 / (1.732 × 415 × 0.85) ≈ 16.1 A, so an 11 kW motor with a suitably rated VFD drive is selected.
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