The No Load Test must be carried out with the motor not connected to the brake; in this condition the System supplies the product under test at different voltages as described in the international standard IEC 60034-2-1. This standard requires in fact that the product under test is powered at different voltages between 125% and 60% of the rated voltage and, if possible, between 50% and 20%. For each supply voltage are acquired the electrical parameters, the thermal resistance and the windings temperature. From these results it is estimated by computing the curve of the iron Losses, which varies with the square of supplied voltage, and therefore losses in the iron at rated voltage. Also, from these results are calculated the values of the losses by friction and of the mechanical ventilation. It’s important to observe that the standard requires that the motor is under the particular conditions of stability in terms of power supply; these conditions can be have achieved if No Load Test is carried out immediately after the Load Test. In other case, it must be enabled an initial stabilization phase.
The test results are all the Electrical Signals, the Current, the Voltage, the Power, the CosFI,the Current Density, the Temperature and the Resistance Value of the Windings.