The external disturbance that has the most influence on CNC machine tools comes from the power grid. It includes electromagnetic radiation interference, voltage fluctuation interference, and load inductance interference.
Electromagnetic radiation interference of the power grid, due to a variety of high-power high-frequency, medium-frequency power supply and various EDM equipment in the factory will generate strong high-frequency electromagnetic waves to radiate into the surrounding space, forming a source of electromagnetic radiation interference. This high-frequency radiation energy is transmitted through the space and is received by the adjacent CNC system. If the energy is sufficient, it will interfere with the normal operation of the CNC machine tool.
Power network voltage fluctuation will also cause interference to CNC machine tools. The CNC system has certain requirements on the allowable range of input voltage, such as 380V±15%, 220V earth 15%, overvoltage or undervoltage can cause power supply voltage monitoring alarm, resulting in shutdown.
The interference caused by the load inductance of the power grid will also have an impact on the CNC machine tool. Larger inductors will release the stored magnetic energy when the power is cut off and form a high-peak narrow pulse in the power grid. Due to the wide frequency range of such interference pulses, especially high-frequency narrow pulses, the peak value is high. The energy is large, the interference is serious, and the speed of change is fast. The power monitoring system is too late to react. If the power supply circuit breaks into the CNC system, it can easily cause an error message and cause the CNC or the programmable controller to stop operating.
