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Entry type: FAQ Entry ID: 5126936, Entry date: 05/05/2016
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MICROMASTER 4 (MM4): determine the stator resistance (p0350)

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p0350 Stator resistance value in [Ohms] for connected motor (from line-to-line).

How is stator resistance (p0350) set?

The three methods for setting the stator resistance value are as follows:

  1. Calculate the stator resistance value using P0340 = 1 or P3900 = 1 or 2. The stator resistance is automatically calculated from the motor information in "Quick Commissioning Mode" (P0010 = 1) by entering P3900 = 1 or 2 (P3900 = 1 Performs calculations and includes factory reset of parameters not in Quick Commissioning group / P3900 = 2 Performs calculations only).
    The value is then stored in P0350.
    Alternatively, once the data from the motor rating plate has all been entered correctly, setting P0340 = 1 also performs the motor parameter calculations and the stator resistance will be stored in P0350.
  2. Measure the stator resistance manually using an Ohmmeter and enter the result in P0350.
  3. Measure the stator resistance internally using P1910.
  • P1910 = 0: no measurement is calculated - the value in P0350 will be used.
  • P1910 = 1: stator resistance measurement - overwrites previous value of P0350.
  • P1910 = 2: stator resistance measurement - does NOT overwrite P0350 - the previous value will still be used.
Once the measurement process is enabled (P1910 = 1 or 2) warning A0541 will be generated, warning that the stator resistance measurement will be performed at the next ON command. When the ON command is given, the inverter measures the stator resistance by applying a current to the motor at 0Hz. It does this at a decreased switching frequency of 2kHz to protect the motor and inverter. This causes a whining sound for the duration of the measurement process, which could last up to 20 seconds.
After the measurement is complete, the warning should disappear, but to get the inverter to run you need to remove the ON command and then reapply it.
The measured stator resistance value can be read in parameter r1912, (and also in P0350 if you select P1910 = 1 to overwrite the previous value in P0350). This value can be used for comparison purposes if you don't have an Ohmmeter.

 

Function Parameter Description Setting Discription
Calculation of motor parameters P0340 Calculates various motor parameters.to optimize inverter performance. 1 Complete parameterization
Stator resistance P0350 Stator resistance value in [Ohms] for connected motor.
MM4: parameter value includes the cable resistance
G120: parameter value doesn't include the cable resistance
xxx in ohm
Select motor data identification P1910 Performs a motor data identification 0 disabled
1 Identification of all parameters with parameter change
2 Identification of all parameters without parameter change
Identified stator resistance r1912 Displays measured resistance value (G120: This value also includes the cable resistances)    
End of quick commissioning P3900 Performs calculations necessary for optimized motor operation 1 End quick commissioning with factory reset
2 End quick commissioning
Motor data identification routine active A0541 motor data identification routine (P1910) selected and is active    

Note
The stator resistance value required is stored in parameter P0350.
This FAQ applies only to the SINAMICS G120/G120D Control Units without “-2” in the product name and MICROMASTER 4 inverters.

FAQ: MICROMASTER 4 (MM4): Optimization of the standard motor identification routine (MOT-ID) for VC and SLVC 37690358 

Application example: MICROMASTER 440: manually determining the magnetizing current and re-calculating the motor equivalent circuit diagram 22078991