Machines that convert electrical energy into shaft work — by far the dominant driver in the process industries (class EM of ISO 14224:2016; design and testing per IEC 60034 / NEMA MG-1).
Usual types
- Induction, squirrel-cage rotor — the industrial workhorse: rugged, brushless, low cost. The Three-Phase Induction Motor handbook is one of the MVP's 5 assets (in production);
- Induction, wound rotor (slip rings) — starting with external resistance: high starting torque on heavy loads;
- Synchronous — large ratings and power-factor correction; separate excitation;
- Direct current — legacy fine speed control, today largely replaced by induction + variable frequency drives.
Reliability: bearings (including VFD-induced shaft currents), stator insulation (thermal — every 10 °C above class halves insulation life, Montsinger's rule) and rotor bars dominate the failure history.