Because the current at the contacts of SF6 density relay is small, there will be no arc between the contacts. The sparks at the contacts are due to the inductance in the contact circuit. When the contacts are disconnected, there will be overvoltage on the inductance. The overvoltage and the power supply voltage are on the contact gap and discharge through the gap that is just separated. Due to the limitation of energy, spark discharge is the only phenomenon. The replacement and transformation of the energy in the capacitance and inductance existing between the contacts makes the spark discharge flicker and become a high-frequency signal.
Furthermore, spark discharge will also cause damage to the contacts and reduce the service life, so it is necessary to eliminate it.
There are two effective spark suppression circuits:
1. Its working principle is to make the energy in the inductor pass through RC (Resistance Capacitance) instead of the contacts.
2. The second working principle is that the energy is consumed on the load when passing through the diode when the contacts are disconnected.
You can choose one method in practice. Please pay attention to choosing the RC with proper parameters which are mainly determined by experiments. Generally, RC can be selected according to the load current 1a/1 microfarad. When using diodes, the positive and negative electrodes should be connected correctly.
If the load of contacts can't meet the application demand, it can be handled by several pairs of contacts in parallel. Adjust the contacts before use to make the synchronization meet the demand. The best way is to choose a central SF6 relay or contactor to expand the load of the contacts.