The following is an analysis of factors that cause resonance in the PLC electrical cabinet sheet metal shell:
1. Influence of external vibration sources
In industrial environments, PLC electrical cabinets are often in complex working scenarios. Large mechanical equipment nearby, such as punching machines and cranes, will generate strong vibrations during operation. These vibrations are transmitted through the ground or air. When the vibration frequency is close to the natural frequency of the PLC electrical cabinet sheet metal shell, resonance is easily induced. For example, in a machining workshop, the frequent punching action of the punching machine will generate periodic vibrations. If the energy of this vibration is transmitted to the electrical cabinet, and the natural frequency of the sheet metal shell of the electrical cabinet happens to be close to it, then the shell will begin to vibrate violently. In addition, the transport vehicles in the factory will also generate vibrations during driving, especially when driving on uneven ground, the vibration will be more obvious. If the electrical cabinet is close to the transportation channel, these vibrations may also cause the resonance of the sheet metal shell.
2. The role of internal component vibrations
Some electrical components inside the PLC electrical cabinet will also vibrate during operation. For example, the cooling fan will generate a certain degree of vibration when running at high speed, and the transformer may also generate slight vibrations due to the action of electromagnetic force when working. When the vibration frequency of these components matches the natural frequency of the sheet metal shell, resonance will be induced. Moreover, if the internal components are not installed firmly, the vibration will be more obvious, thereby increasing the risk of resonance. For example, if a cooling fan is not fixed tightly, it will produce large vibrations when running. This vibration is transmitted to the sheet metal shell and may cause the shell to resonate. In addition, some high-power electrical components will also produce large impact forces at the moment of starting and stopping, and this impact force may also cause the resonance of the sheet metal shell.
3. Sheet metal shell design and manufacturing factors
Irrational design of sheet metal shell is an important factor leading to resonance. If the thickness of the sheet is uneven, the vibration amplitude of different parts will be inconsistent when subjected to external or internal vibration, which is easy to produce local resonance, and then cause resonance of the entire shell. At the same time, unreasonable structural design, such as improper arrangement of reinforcement ribs and irregular shell shape, will also affect the natural frequency of the shell, making it more likely to resonate with external or internal vibration sources. During the manufacturing process, if the welding quality is poor, there are cold welding, leaking welding, etc., the structural strength of the shell will be reduced, and it is easy to deform under the action of vibration, thereby causing resonance. In addition, improper surface treatment may also affect the vibration characteristics of the housing. For example, if the coating is too thick or uneven, it may change the mass distribution of the housing, thereby affecting its natural frequency.
4. Influence of installation and fixing methods
The installation and fixing method of the PLC electrical cabinet also plays a key role in whether resonance occurs. If the installation is not firm and there is a gap between the electrical cabinet and the installation foundation, the electrical cabinet will be more likely to shake when subjected to external vibration, thereby increasing the possibility of resonance. For example, the use of inappropriate bolt specifications, insufficient tightening force, or uneven installation foundation will lead to a decrease in the stability of the electrical cabinet. In addition, if appropriate shock-absorbing measures are not taken, such as installing shock-absorbing pads, spring shock absorbers, etc., the electrical cabinet will directly bear external vibrations, which is easy to cause resonance of the sheet metal housing. Especially in some environments with large vibrations, the lack of shock-absorbing measures will greatly increase the risk of resonance.
