Siemens 420 manual Motor data identification stator resistance

3 Functions Issue 07/04

3.5.4Motor data identification (stator resistance)

MICROMASTER has a measuring technique which is used to determine the stator resistance:

We urgently recommend that the identification routine is carried-out for control- related reasons. For example, the stator resistance is extremely important for the voltage boost for the V/f characteristic. The motor data identification routine should be executed, especially if long feeder cables or if third-party motors are being used.

After selecting the motor data identification using parameter P1910, alarm A0541 is immediately generated. The motor identification routine is started by the ON command and different excitation signals are impressed in the motor (DC and AC voltages). This measurement is carried-out with the motor at a standstill and it takes, including the data calculation per selection (P1910 = 1) between 20 s ... 4 min. The identification time depends on the motor and increases with its size.

The motor data identification routine must be carried-out with the motor in the cold condition so that the motor resistance values saved can be assigned to the parameter of the ambient temperature. Only then is correct temperature adaptation of the resistances possible during operation.

The motor data identification routine operates with the results of the "Complete parameterization" P0340 = 1 or the motor equivalent diagram data which was last saved. The results become increasingly better the more times that the identification routine is executed (up to 3 times).

WARNING

It is not permissible to carry-out the motor identification routine for loads which are potentially hazardous (e.g. suspended loads for crane applications). Before starting the motor data identification routine, the potentially hazardous load must be secured (e.g. by lowering the load to the floor or clamping the load using the motor holding brake).

When starting the motor data identification routine, the rotor can move into a preferred position. This is more significant for larger motors.

NOTE

It is not necessary to lock the motor rotor for the motor data identification routine. However, if it is possible to lock the motor rotor during the identification routine (e.g. by closing the motor holding brake), then this should be used to determine the equivalent circuit diagram data.

The following formula can be applied to check the correctness of the motor rating plate data:

PN = √ 3 ∗ VN Υ ∗ INΥ

with PN

VN Υ , VN ∆

IN Υ , IN ∆ cosϕ

η

∗ cosϕ ∗ η ≈ √ 3 ∗ VN ∆ ∗ IN∆ ∗ cosϕ ∗ η

rated motor power

rated motor voltage (star / delta) rated motor current (star / delta) power factor

efficiency

MICROMASTER 420	Operating Instructions
70	6SE6400-5AA00-0BP0