Uses of electrical energy and features of drives

Electrical energy is used by three main consumer groups. In each, a large part of the load is electric drives (motors driving machines), whose type depends on the load's needs.

Domestic use

• Lighting (LED, CFL), fans, TV, computers, refrigerators, washing machines, water pumps, mixers, vacuum cleaners, rice cookers, induction stoves, water heaters, irons.
• Supply: 230 V single-phase (400 V three-phase for large houses).

Features of drives used

• Small fractional-kW motors, mostly single-phase induction motors (capacitor-start, capacitor-run, shaded pole) for fans, pumps, refrigerator compressors.
• Universal (series) motors for mixers, vacuum cleaners, drills: high speed, high starting torque, work on AC and DC.
• BLDC motors in modern ceiling fans and inverter compressors: high efficiency, speed control.
• Requirements: low cost, quiet operation, maintenance-free, reliable.

Commercial use

• Lighting, air-conditioning and heating (HVAC), lifts and escalators, water pumping, refrigeration in shops and hotels, computers and servers, kitchens.
• Supply: 400 V three-phase, or 11 kV for large buildings.

Features of drives used

• Three-phase induction motors for pumps, fans, compressors (simple, robust).
• Lifts and escalators: induction motors with variable-frequency drives (VFD); smooth acceleration, accurate stopping, regenerative braking; earlier DC (Ward-Leonard) drives.
• HVAC with VFDs on fans and pumps for energy saving at part load.
• Requirements: smooth, quiet operation, safety, energy efficiency.

Industrial use

• Machine tools, rolling mills, cranes and hoists, conveyors, pumps, compressors, crushers, textile and paper machines; electric furnaces, welding, electrolysis; lighting.
• Supply: 400 V (small), 11 kV (medium), 33 kV and above (large).

Features of drives used

• Squirrel-cage induction motors: most common; constant-speed loads like pumps, fans, compressors.
• Slip-ring induction motors: high starting torque (cranes, crushers, hoists), speed control by rotor resistance or slip-power recovery.
• Synchronous motors: constant speed, large compressors, power-factor improvement.
• DC motors (series for traction and cranes, shunt for machine tools): wide speed range, now often replaced by VFD-fed induction motors.
• Stepper and servo motors: precise positioning in CNC and robotics.
• Requirements: correct torque-speed match, starting and braking, speed control, duty cycle, overload capacity, protection, efficiency.