If you send us in addition to the a.m. data the following information, we can exactly calculate the start current of your application

Data of motor

• Start current of motor for direct on line start as I_a / I_n or in A
  start current of the motor with reduced voltage, if available but not absolutely necessary
• Torque speed curve of the motor, which is depicted mostly as follows: 
  (we can also work with any other deviating shape):
   
  
  
  • Alternatively, if no curve exists, you may state
    
    • start torque M_a/M_n
    • break away torque M_k/M_n
    • If the start torque is not the lowest torque value:
      pull-up torque M_s/M_n = the lowest value of the torque
    • Torque speed curve of the motor at reduced voltage, if available but not absolutely necessary 
   

Data of driven machine

• Torque speed curve of the driven machine (counter torque) which is depicted mostly as follows:
  (we can also work with any other deviating shape): 
   
  
  
  Alternatively, if no curve exists, you can describe the shape of the curve (f.ex. starts at T/T_n = 0,17, ends at T/T_n = 0,3, has the lowest point T/T_n = 0,1 at n/n_n = 0,3)
   
• The rated power of the driven machine (to which the diagram above refers) if it deviates from the rated power of the motor.

Remark: Within this context we would like to point out our interactive start current calculator. You can get a first impression of the possible start current of your application if you like.

If you can submit the following additional data to the ones mentioned above, we can calculate the starting time of your application:

• Data of motor
  • rated speed n [rpm]
  • moment of inertia J [kgm²]
• Data of the driven machine
  
  • moment of inertia J [kgm²] (including all rotating parts, as f.ex. couplings, gear boxes, etc., if existing)

The technical data which have been listed up to now are sufficient to produce the starter.

Would you also like to know the voltage drop of your application?

For the calculation of the voltage drop technical data of your MV grid are necessary.
These are:

• minimum mains short circuit power at the voltage level to which the motor is connected namely Sk" [kVA] 
  or

• minimum mains short circuit power of a higher voltage level Sk" [kVA] and the following data of the power transformer, which is located between both of the voltage levels:
  
  • rated power S [kVA]
  • short circuit power u_k [%]
• We are also able to calculate grids with multiple voltage levels / transformers
• total rated power of motoric loads, which are operated parallely to your application on the same voltage level , if available but not absolutely necessary
  

  In many cases single line diagrams of MV grids are present. If you send us such a diagram, a description of the grid and the schedule of the different technical parameter is not required.