Thyristors are used as control elements for triggered controllers, also known as phase fired controllers. There are many types of thyristors of which these are some:
o ASCR Asymmetrical
o GTO Gate Turn Off Thyristor
o SITh Static Induction Thyristor
o IGCT Integrated Gate Commutated Thyristor
Thyristors are commonly employed when high currents and high voltages are used, and thyristors are very often employed to regulate alternating currents. Thyristors are also found in power supplies for digital circuits, where they are used as a circuit breaker. Thyristors are used as control elements for triggered controllers, also known as phase fired controllers.
Thyristors are solid state semiconductor devices. Thyristors have four layers of alternating N and P type material. This enables thyristors to act as switches, they conduct when their gate receives a current pulse, and they continue to conduct for as long as they are forward biased.
Thyristor power switches are used for the contact free switching of AC loads. A typical application is the switching of resistive inductive loads at high switching rates, especially in the industrial sector such as the plastics packing industry, and in the construction of industrial furnaces.
The control and power sections are electrically isolated by optocouplers, and the control range is compatible with the logic outputs of JUMO controllers.
The power section operates as a zero voltage switch, which means that it always switches when the voltage passes through zero, irrespective of interference voltages. A varistor is integrated on the output side as a protection against voltage spikes.
Different types of thyristor switches are used for various applications and some of these switches may or may not have the following features:
o Thyristor power switch without heat sink
o Thyristor switch with analogue control
o Thyristor switch with integrated cooling body
Thyristor units consist of two thyristors connected in inverse parallel, the isolated heat sink and the control electronics.
Thyristors units are used in all applications where larger resistive and inductive loads have to be switched for example in industrial furnaces and in plastic processing.
