What is the difference between scr and gto

In operation, SCR acts conducting when a pulse is provided to the gate. SCR is a power device and most of the times it is used in applications where high currents and voltages are involved. The most used SCR application is controlling rectifying alternating currents. GTO is also a type of thyristor made of four P type and N type semiconductor layers, but the device structure is little different compared to SCR.

These electrons as well as holes-injection continuous till the gate turn off thyristor enters into the conduction region. In thyristor, at first, the conduction begins through switch ON the region of cathode contiguous to the gate terminal. Thus, the remaining region comes into the conduction through plasma spreading. Therefore, the gate turns off thyristor comes into the conduction region very fast. At the gate terminal, a reverse bias can be applied to switch OFF a conducting thyristor by making the gate terminal negative as compared with the cathode.

In the P-layer, a fraction of the holes can be extracted using the gate terminal to hold back the electrons injection from the cathode terminal.

In reply to this, an extra hole current can be removed by the gate terminal which results in more control of electrons from the cathode terminal.

Throughout the process of hole extraction, the area of the p-base is slowly exhausted so that the conduction region can be squeezed. As this procedure continues, then the anode current supplies in remote areas by forming filaments with high current density. So, this can cause limited hot spots which can damage the device if not these filaments are extinguished rapidly.

During the high negative gate voltage application, these filaments are extinguished quickly. Because of the stored charge in the N base region, the anode terminal to gate current flows continuously although the cathode current is stopped. So, this is known as a tail current which decomposes exponentially when the surplus charge carriers are decreased through the recombination procedure.

When the tail current level is decreased to a leakage current level, then the device keeps the characteristics of forwarding blocking. Therefore, it does not conduct in this mode. In this mode, the GTO simply blocks the rated forward voltage when the gate terminal is biased negatively to the cathode. When a positive gate signal is given with appropriate amplitude to the GTO, then it moves into the mode of forwarding conduction. Apart from the above tabulated differences, the on stage voltage drop and associated losses are more in GTO.

Its gate drive losses are also on higher side as compared to SCR. Notify me when new comments are added. GTO is a four-layer , three terminal pn pn device. SCR is also a four-layer, three terminal pn pn device. This is the basic structural difference between the two.

It is represented by the either circuit symbol i or ii shown below.