Electrical Motors Torques
Reference data and engineering information about electrical motors torques for electrical applications.
electricalmotorstorquesCalculator
Overview
Engineering reference data for Electrical Motors Torques in electrical engineering.
Key Formulas
Ohm's Law
Voltage = Current × Resistance.
Power
Electrical power.
Energy
Energy = Power × Time.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Voltage | V | |
| Current | A | |
| Resistance | Ω | |
| Power | W |
Motor Torque Characteristics
The torque of an asynchronous induction motor changes as it accelerates from standstill to full speed. Key performance points include:
- Locked Rotor Torque (Starting Torque): The torque produced at zero speed. A high starting torque is essential for high-inertia loads like cranes or positive displacement pumps. Low-inertia loads like fans may require less starting torque.
- Pull-up Torque: The minimum torque generated as the motor accelerates, occurring after the initial torque dip. It's critical for overcoming temporary load increases during startup.
- Break-down Torque: The maximum torque the motor can develop before a significant drop-off. It represents the peak torque limit during acceleration.
- Full-load (Rated) Torque: The torque required to produce the motor's rated power at its rated speed.
NEMA Motor Designs
The National Electrical Manufacturers Association (NEMA) classifies motors into four standard designs (A, B, C, D) based on their torque characteristics (starting, pull-up, breakdown) and starting current, catering to different application requirements. IEC standards have similar classifications.