Method of eliminating the spark of relay contact

Since the current of the relay contact is small, there is no arc between the contacts, but there will be a "spark discharge". This is because there is an inductance in the contact circuit, and an overvoltage occurs in the inductor when it is disconnected. They are added together on the contact gap, so that the contact gap just separated by a certain distance is broken down and discharged. Due to the limitation of energy, only spark discharge is generated, and the alternating energy between the capacitor and the inductor in the contact makes the spark discharge appear in time, and becomes a high-frequency signal, and the spark discharge is also damaged. , but will reduce the service life, so must be managed to eliminate, there are two practical spark-eliminating circuits. one. The basic principle of action is to make the energy in the inductor pass through rc without passing through the junction; When disconnected, it is consumed by the diode v on the load r.l. Just choose one of the apps. However, it should be noted that the rc parameter should be selected appropriately, and the parameters are mainly determined by experiments. Usually, the capacitance c can be selected by the load current 1a/1 micro method. When using a diode, its positive and negative polarity should be connected correctly.