Description
„ac-motor start“ represents a tool for professionals (engineer, site manager, site designer, maintenance personal) to estimate the behavior of the supply network and the drive at the start of the motor.
„ac-motor start“ allows estimating the influence of the multiple nominal current during the start of a 3-phase asynchronous motor to the feeding electrical network levels and the resulting change of the motor characteristics. Final dimensioning of different plant components however needs a detailed calculation.
–Data input–
For the calculation of the voltage drop on the different voltage levels it is possible to select the configuration of the feeding components by click:
* Net capacity
* High voltage
* Medium voltage
* Low voltage = motor rated voltage
The configuration will be displayed graphically.
Selectable by click are different start methods in case that the calculation should not be done with direct start:
* Y/D
* Autotransformer
* Frequencyconverter
* Softstart
* reactor
The selected start method will be displayed graphically.
The calculation needs following input data:
* Feeding net –> capacity
* Transformers –> rated data
* Load data –> M=f(n) (optional if start time shall be calculated)
* Motor –> rated data according data sheet
* Start method –> start current / tap etc. according start method
According these data the resulting voltages on the different voltage levels and the resulting start up time will be calculated. In case that the data of the feeding net or that the transformers should not be included in the calculation, its influence on the voltage drop will be unaccounted. The relevant input boxes will be invisible.
–Torque/speed characteristic–
Three different torque/speed characteristic of the motor or an individual characteristic can be selected:
* Squirrel cage motor
* Double squirrel cage motor
* High bar cage motor
* Individual data according data sheet
The three standard characteristics can be simply adjusted by adapting the initial torque and the peak torque. If the proper torque vs. speed characteristic of the motor is known, the data can be inserted individually.
The torque characteristic of the load can be designed by 2 parameters (constant and variable part) or inserted individually.
The torque vs.speed characteristics under the different conditions will be displayed graphically.
–Start current characteristic—
The characteristic of the start current is similar an all motors. The current at start and the declination degree of the graph can be adapted simply.
The characteristic of the current under different conditions will be graphically displayed.