Gate Turn Off Thyristor Technology
A gate turn off thyristor is a unique class of thyristor, a high voltage semiconductor device used in electric motor gates. It was innovated by GE. GTOs, unlike regular thyristors, are semi-controlled switchable gates that can be activated and turned off by their respective third lead, the gate switch. The electrical current passing through the system passes through a buffer that is electrically disconnected between the two leads.
It is used in many applications to avoid an undesirable trip of gate turn off in switching characteristics and other necessary circuit operation steps. The switching characteristics of this device are highly depend upon the amount of current passing through it. Any sudden change in current will make the gate to be closed and the turning of the switch to on will take place. This feature helps in avoiding undesirable circuit changes.
There are several reasons for which a gate terminal is preferred over other conventional terminals. First of all, it offers a much greater measure of safety and security compared to conventional terminals. It is capable of producing a commutation circuit that can withstand heavy loads and high current. Moreover, the turn off characteristic makes it safe from shorts, tripping and other undesired events. With the turn off feature, it can be assured that the turning of the light or motor will not interrupt the commutation circuit.
A gate terminal is available in different types and varieties. It can be a full turn off, which means it does not permit any further flow of main current. In addition, it can provide a short cut to the main current, which means it can be used in some appliances like night light bulbs, electric lamps and some electric motors. The second type is the short cut function that permits the flow of main current for some specified time. It is basically used in emergency situations when you need to turn the power off as soon as possible. The last type is called a permanent flip-off that only allows the flow of main current when the appliance is switched off.
Gate Turn Off Thyristor has two main categories, namely, full turn off and short cut function. Full turn off offers a higher level of security than the previous one, while short cut function allows higher level of flexibility. Basically, it can work in two manners; manual and automatic. In manual mode, it can be controlled with the help of a switch and sometimes with the help of a touch pad. It can also be controlled with the help of a bridge that connects the input side and the cathode junction.
Gate Turn Off Thyristor features three main categories, namely, Full Reverse bias, Full Spread, and Full Switching. Full Reverse bias can only turn the gate terminal fully or partially, whereas Full Spread and Full Switching allow the full flow of current. Plasma Spitting refers to the technology employed to control the current, which includes the pulse width modulation, variable pulse width, and non-polarized conductive switching. These methods include the generation of electromagnetic fields or electric fields that alter the permeability of the solid or semiconducting layer by inducing atoms into an excited state, thereby altering the current.