|Electrical Machines - Basic vocational knowledge (Institut für Berufliche Entwicklung, 144 p.)|
|3. Execution of rotating electrical machines|
Rating plates of rotating electrical machines must provide information with regard to the keynote date of the machine in point. Such details are, moreover, necessary for assessing the suitability of the machine for linkage to adjacent technical facilities, mains, work units and prime movers. Consequently, rating plates feature a wealth of details concerning technical-physical dimensions and particular design characteristics. Moreover, additional data is similarly required for possible further fixtures. Such on-going data pertains, inter alia, to rated operating type. Machines in the power range of 0.001 kW to 1.1 kW must feature:
- country of origin
- manufacturer or his trademark
- index or type
- nominal voltage and current type
- nominal torque and, if required, additional nominal frequency
- capacity and rated voltage of the capacitor
- machine number, year of manufacture or month resp. week and year of manufacture.
Designation pattern range of machines in the power range over 1.1 kW:
Figure 29 - Rating tag of an electrical machine (sample)
2. machine designation - type
3. machine number, year of manufacture; or month and year of manufacturer; resp. week and year of manufacture
4. current type
5. mode of operation (mot; gen; power gen; U; B1 M)
6. winding circuitry
7. rated voltage
8. rated current
9. rated power of supplied rating in W, kW, MW; in VA, kVA and MVA for alternating current synchronous generators and reactive power machines
10. rated frequency
11. capacity, rated voltage of the capacitor (for single-phase motors with starting or working capacitors)
12. rated power factor
(Power factor l = displacement factor cos j applies where current and voltage change sine-shaped.
l = cos j can be used for practical sine-shaped values)
13. torque (all rated speeds; in torque adjustable machines the highest and lowest nominal drive torque of the speed range; in machines over 1.1 kW in series operation and machines with a greater operational torque as compared to rated torque, torque speed and the highest permissible speed shall be given)
14. rotational direction (only if required)
15. rated operational mode (apart from S1)
16. insulation class
17. Rated exciting current; rated exciting voltage (exc....A; esc....V)
18. nominal stillstand voltage between the slip-rings given rated operation (Lf...V)
20. number of standard
21. quality sign
23. degree of protection
Questions for repetition and control
1. What characterises the design of a motor?
2. Which degree of protection must be selected for a motor positioned in moist surroundings?
3. What does operational mode S1 denote?
4. How is clockwise running stipulated for electric motors?