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close this bookElectrical Machines - Basic Vocational Knowledge (IBE - Deutschland; 144 pages)
View the documentIntroduction
Open this folder and view contents1. General information about electrical machines
Open this folder and view contents2. Basic principles
close this folder3. Execution of rotating electrical machines
View the document3.1. Size
Open this folder and view contents3.2. Designs
Open this folder and view contents3.3. Degree of protection
Open this folder and view contents3.4. Cooling
close this folder3.5. Mode of operation
View the document3.5.1. Definition
View the document3.5.2. Operational mode designation
View the document3.5.3. Frequent nominal cycle ratings
View the document3.6. Heat resistance categories
Open this folder and view contents3.7. Connection designations of electrical machines
Open this folder and view contents3.8. Rotating electrical machines in rotational sense
View the document3.9. Rating plate
Open this folder and view contents4. Synchronous machines
Open this folder and view contents5. Asynchronous motors
Open this folder and view contents6. Direct current machines
Open this folder and view contents7. Single-phase alternating current motors
Open this folder and view contents8. Transformer
 

3.5.3. Frequent nominal cycle ratings

Operational mode S1

Nominal load machine running continues (tB) until machine heating up has attained its final temperature which does not increase further.


Figure 26 - Rated operating type S1

Legend as for Figure 28

The final temperature shall not exceed the limit temperature heat resistance category of the machine.

Operational mode S2

Nominal load machine running continues until the limit temperature of the machine has been attained. Then there is a break which lasts until the machine temperature has attained room temperature. The desired values of 10, 30, 60 and 90 minutes apply for the duration of short-time operation.


Figure 27 - Rated operating type S2

Legend as for Figure 28

Operational mode S3

The machine runs in periodical operation in a permanent sequence of like cycles (tSP). Each cycle includes nominal load or operation and a break (tP) with standstill time whereby the starting current exerts no perceptible influence on heating up.


Figure 28 - Rated operating type S3

1 Power
2 Power loss
3 Operating time (tB)
4 Down time (tP)
5 Cycle play time (TSP)

The machine temperature does not return to room temperature during the standstill period. Intermittent operation is characterised through the relative cycle duration factor tr and the cycle of ten minutes. The cycle duration indicates the various, repeatedly occurring operating conditions. The relative cycle duration factor (t)r is indicated thus:

By way of preference 15, 25, 40 and 60% should apply in respect of the relative cycle duration factor.

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