Elevator Motor Power
Calculate the motor power of an elevator, P = m·g·v ÷ η, from the payload m (kg), gravity g (9.81 m/s²), nominal speed v (m/s) and the system efficiency η (motor, gearbox, sheaves). The result, in watts, is the mechanical power needed to hoist the load at nominal speed. In practice, the counterweight (balancing the car plus ~45% of the load) reduces the effective power, and regenerative braking on descent can return some to the system. It is the base calculation for sizing the traction machine. Enter the load, the speed and the efficiency.
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Elevator motor power
The motor power of an elevator is the mechanical power needed to hoist the load at the rated speed: P = m·g·v ÷ η, where m is the payload, g gravity, v the speed and η the efficiency of the traction assembly (motor + gearbox + sheaves, typically 0.6-0.85). The result is the peak power while hoisting. But the practical calculation carries an important subtlety: the counterweight. An elevator does not lift the load from scratch — the counterweight (which balances the car plus roughly 45% of the rated load) does almost all of the balancing work, and the motor only has to overcome the imbalance. The effective power is therefore much smaller than hoisting the full load. On top of that, modern elevators with variable-frequency drives (VVVF) and regeneration return energy to the grid on the way down (when the counterweight descends with a light car). This formula gives the baseline reference; real sizing accounts for the counterweight, the duty cycle, the accelerations and the efficiency of each component. Enter the load, the speed and the efficiency.
Related Tools
Handling Capacity (5 min)
Calculate an elevator's handling capacity over 5 minutes, HC = (300 × Q) ÷ RTT, from the car capacity Q (people) and the round trip time RTT (s). The result, in people carried per 5 minutes, is the standard vertical-traffic performance metric (building peak demand is usually measured over 5 min). The factor 300 is the seconds in 5 minutes. Multiplied by the number of elevators and compared with the building population, it tells whether the system meets demand (typically 12-15% of the population in 5 min in offices). Enter the car capacity and the RTT.
Building Population
Estimate a building's population, Pop = (area per floor × number of floors) ÷ density, from the usable area per floor (m²), the number of floors and the occupancy density (m² per person). The result, in people, is the total population to be served by the vertical transport — the starting point of elevator traffic analysis. Occupancy density varies with use: ~10 m²/person in dense offices, ~15-20 m²/person in standard offices, with specific values for hotels and residences. Compared with the elevators' handling capacity, it tells whether the system is adequate. Enter the area per floor, the number of floors and the density.
Motor Power (Torque × RPM)
Compute a motor's mechanical power from torque and rotation, P = τ·ω = τ·2π·n/60, where τ is the torque (N·m), n the rotation (rpm) and P the power (W). It is the fundamental relation linking the three quantities of a rotating motor: the same motor delivers high torque at low speed or high speed at low torque, but the power is the product of the two. The basis of drive sizing. Enter the torque and the rotation.
Three-Phase Voltage Unbalance (NEMA)
Measures the unbalance of the three line voltages of a three-phase system by the NEMA MG-1 criterion, the same one used by motor derating curves. The calculation takes the average of the three line voltages, finds the largest absolute deviation between any voltage and that average, and divides this deviation by the average, as a percentage. The number has a direct consequence: NEMA forbids operating induction motors above 5%, recommends derating from 1% on (at 2% the derating factor is already about 0.95) and warns that 1% of voltage unbalance can become 6 to 10% of current unbalance, with extra rotor heating. The NEMA definition was adopted (largest deviation divided by the average, also called LVUR) rather than the IEC and IEEE unbalance factor, which is the ratio between negative and positive sequence components and requires full phasors, not just magnitudes. Enter the three measured line voltages.
Boost Converter (Step-Up)
Calculate the output voltage of a boost (step-up) DC-DC converter in continuous conduction, V_out = V_in ÷ (1 − D), from the input voltage V_in and the duty cycle D (0 to 1). The result, in volts, is always greater than the input — the boost converter raises voltage by storing energy in an inductor and releasing it in series with the source. As D approaches 1, the output tends to infinity (limited by real losses). It is used in supplies that must step up voltage (LEDs, batteries, power factor correction) and in photovoltaic systems. Enter the input voltage and the duty cycle.
Counterweight Mass
Calculate an elevator's counterweight mass, M_cw = M_car + factor × Q_max, from the car mass, the balancing factor (typically 0.40 to 0.50) and the maximum load Q_max (kg). The result, in kg, is the mass that balances the car plus a fraction of the payload, so the motor works with the smallest average imbalance. A factor of 0.45 (45%) is common: it fully balances the car and 45% of the rated load, minimizing motor work both with a full and an empty car. Enter the car mass, the balancing factor and the maximum load.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.