Snubber Circuit – Types, Working, and purpose
A Snubber circuit is an essential part of an electronic circuit that is used to protect sensitive electronic components from voltage spikes or transient faults. It is consisting a series combination of resistor and capacitor and which is always connected in parallel with the protected part of the circuit.
Generally, Snubber Circuit is used in parallel with the thyristor to prevent the unwanted triggering of the thyristor at the time of switching. During the switch ON or OFF condition, dv/dt also change from 0 to running voltage or running voltage to 0. Due to changing of dv/dt, the connected thyristor of the circuit may also operate or trigger without a snubber circuit.
Working Princip of Snubber Circuit
As shown in the figure, snubber circuit is connected in parallel with the Thyristor unit. At the time of the ON or OFF condition of switch S1, dv/dt will generate in the circuit. Due to the placement of the capacitor in the circuit, during changing of dv/dt, the capacitor conducts and the power is dissipated across the resistor. In this way, it protects the thyristor from unwanted triggering during switching.
As We know, current through the capacitor is I=Cxdv/dt
During the steady state position, the value of dv/dt is zero as there is no change in voltage. So the current through the capacitor is zero and it acts like an open circuit. At the time of switching, dv/dt is generated across the circuit and the current will pass through the capacitor unit.
Types of Snubber Circuit:
There are 03 types of Snubber circuits that are generally used in the switching circuit. They are
- RC Snubber
- RCD snubber
- RLC snubber
RC snubber circuit consists of a series combination of resistors and capacitors. It is used to protect the electronics component against the sudden changing of voltage due to switching or any inductance effect. Under RC snubber circuit, current flows through the resistor at both switch ON or OFF conditions.
RCD snubber circuit consists of the series combination of resistor and capacitor along with the diode in parallel with the resistor as shown in the picture. Like RC snubber, it is also protecting the components against the sudden changing of voltage due to switching or inductance effects.
As the Diode is connected in parallel with the resistor unit, at the time of switch ON, the current will pass through the diode, and at the time of switch ON, the discharge current will pass through the resistor.
Following are the advantages of RCD snubber over RC snubber
- Reduced the total circuit loss which is included both switching and the circuit loss.
- A better load line can be achieved by using the RCD snubber due to proper control of current through the capacitor.
RL snubber circuit consists of the parallel combination of an Inductor and resistor. It is used to protect the circuit due to sudden energy dissipation or changing current. During running conditions, current flows through the inductance, and at the time of switch OFF, the current is forced to zero and it generated di/dt in the circuit. It will block the high current through the primary circuit.