vaihtovirtakierroksella

Vaihtovirtakierroksella refers to a synchronous motor operating at a frequency that differs from its rated frequency. In a standard synchronous motor, the rotor rotates at a speed directly proportional to the frequency of the applied alternating current and the number of poles in the motor. This relationship is defined by the synchronous speed formula: n_s = 120f/P, where n_s is the synchronous speed in revolutions per minute, f is the frequency in Hertz, and P is the number of poles.

When a synchronous motor is operated at a frequency other than its designed frequency, it is said to be running "vaihtovirtakierroksella". This can occur in several scenarios. One common situation is when a variable frequency drive (VFD) is used to control the motor speed. A VFD can adjust the output frequency supplied to the motor, allowing for operation at speeds below or above the synchronous speed corresponding to the mains frequency.

Another instance might be due to fluctuations in the power supply frequency, although this is less common in stable power grids. Operating a synchronous motor at a frequency other than its rated value affects its operating characteristics, including torque, power output, and efficiency. The motor can still produce torque and rotate, but its performance parameters will deviate from the optimal design conditions. Special considerations might be needed for insulation and thermal management if operated significantly outside the intended frequency range for extended periods.