Static Switch
Definition of Static Switches :
- The SCRs and Triac are latching type devices. They can be either fully on or fully off.
- So they are equivalent to closed switches when conducting and open switches when off.
- Therefore SCR and triac are known as the static switches. The word “Static” is used because there are no moving parts in such switches.
- The static switches are bidirectional switches that means they allow the current to flow in both the directions through them.
Static Switch using Inverse Parallel SCRS :
Circuit Diagram of Static Switches :
Figure shows the circuit diagram for the static switch using two SCRs connected in inverse parallel configurations.
Operation of Static Switches :
- SCR1, will act as a closed switch in the positive half cycle of the ac supply and will deliver power to the load.
- SCR2, will act as a closed switch in the negative half cycle of the ac supply and delivers power to the load.
- The RC circuit shown in Figure is called as the snubber circuit. It is used to avoid the accidental firing of the SCRs.
- The SCR static switch can be used in the frequency range upto 400 Hz.