Thyristor FAQs:

Q: Is a thyristor a solid-state semiconductor device with four layers of alternating N and P-type material?

A: Yes.

Q: Are thyristors activated by light?

A: Yes.

Q: Are thyristors poor candidates due to large switching times arising from bipolar conduction?

A: Yes.

Q: Is a thyristor cooled with deionized water?

A: Yes, and the entire arrangement becomes one of multiple identical modules forming a layer in a multilayer valve stack called a quadruple valve.

Q: Are thyristors their insensitivity to electrical signals?

A: Yes, and which can cause faulty operation in electrically noisy environments.

Q: Is a thyristor that?

A: Yes, and like a diode, it only conducts in one direction.

Q: Is a thyristor not a proportional device like a transistor?

A: Yes.

Q: Are thyristors more usually made by electron or proton irradiation of the silicon?

A: Yes, or by ion implantation.

Q: Are thyristors often used in frequency changers and inverters?

A: Yes.

Q: Is a thyristor designed to control the larger current of its two leads by combining that current with the smaller current of its other lead?

A: Yes, and known as its control lead.

Q: Are thyristors arranged into a diode bridge circuit and to reduce harmonics are connected in series to form a 12-pulse converter?

A: Yes.

Q: Is a thyristor a four-layered, three terminal semiconductor device, with each layer consisting of alternately N-type or P-type material, for example P-N-P-N?

A: Yes, The main terminals, labelled anode and cathode, are across all four layers.

Q: Are thyristors heavily used in megawatt-scale rectification of AC to DC?

A: Yes, and in low- and medium-power applications they have virtually been replaced by other devices with superior switching characteristics like Power MOSFETs or IGBTs.

Q: Are thyristors available with in-built over-voltage protection, which triggers the thyristor when the forward voltage across it becomes too high?

A: Yes, they have also been made with in-built forward recovery protection, but not commercially.

Q: Is a thyristor used in conjunction with a Zener diode attached to its gate, and if the output voltage of the supply rises above the Zener voltage, the thyristor will conduct and short-circuit the power supply output to ground?

A: Yes, This kind of protection circuit is known as a crowbar, and has the advantage over a standard circuit breaker or fuse in that it creates a high-conductance path to ground for the damaging supply voltage and potentially for stored energy in the system being powered.

Q: Are thyristors still the primary choice?

A: Yes.

Q: Are thyristors mainly used where high currents and voltages are involved?

A: Yes, and are often used to control alternating currents, where the change of polarity of the current causes the device to switch off automatically, referred to as "zero cross" operation.