Motors, generators and transformers: windings, operation and energy optimization
From servo and frequency converter to winding a motor and saving energy on the system
An earlier article provided an overview of the components in an automatic system. Here we go deeper into one of the most important: the electric motor in all its forms — from the common induction motor to the servo motor that positions an axis with a fraction of a millimeter accuracy. It is a field of study that at the same time contains some of the education's most hands-on disciplines such as winding motors and transformers.
§Servo stepper motor and frequency converter
Learning outcome no. 14 requires that the apprentice can apply servo technology, stepper motors and frequency converters in development and assembly tasks and perform troubleshooting, error correction and optimization. The three technologies solve each their task. A stepper motor moves in fixed, discrete steps and is used where simple and relatively cheap positioning is enough. A servo motor works with feedback from a position sensor, so the controller can continuously correct and achieve very high precision, even under varying load. The frequency converter instead regulates a normal motor's speed and torque by changing the frequency and voltage of the current the motor is supplied with — it is typically used where speed regulation is needed without the servo's high precision requirements, such as on pumps, fans and conveyor belts.
- 01Stepper motor — moves in fixed steps, simple and robust positioning
- 02Servo motor — feedback control high precision under varying load
- 03Frequency converter — regulates speed and torque on standard motors, energy-efficient operation
§Winding — the craftsmanship behind the engine
Learning outcomes no. 26 and 27 require that the apprentice can perform winding on motors, generators and transformers and build, commission and maintain equipment with these machines. Winding is about laying copper wire in specific patterns around an iron core to create the magnetic field that drives or generates current. If the winding is faulty — for example shorted between two windings, or insulation broken down by heat and age — the motor will typically become hot, lose power or trigger an error message. Being able to measure and repair a winding is a classic but still relevant competence, especially on older or custom-built equipment where a new motor cannot simply be ordered.
§Energy optimization and green transition
Learning outcomes no. 13 and 28 are both about energy optimization — on automatic machines and industrial equipment in general, and specifically on motor installations, generators and transformers — based on knowledge of green transition in industrial production. In practice this means, among other things, assessing whether a motor is correctly sized for the task (an oversized motor often runs inefficiently at partial load), whether a frequency converter can replace simple on/off control to save energy at partial load, and whether heat from motors and transformers can be reused instead of being lost.
| Component | Typical error to look for |
|---|---|
| Standard motor | Worn bearings, imbalance, overheating, falling insulation resistance |
| Servo motor | Error in position sensor, cable break, overheated amplifier |
| Frequency converter | Over-temperature, error in current limitation, incorrect parameter setting |
| Transformer | Broken winding insulation overheating loose connections |
§Commissioning and maintenance
When a motor, generator, or transformer is put into operation, things are checked including rotation direction, load current relative to the nameplate, temperature during operation, and mechanical fastening. Preventive maintenance—thermography, vibration measurement, and periodic insulation tests—makes it possible to detect a developing fault long before the motor actually stops in the middle of production.