Silicon Controlled Rectifier Overview

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What is the main purpose of a Silicon Controlled Rectifier (SCR)?

To function as a general diode
To convert DC current into AC current
To amplify electric signals
To control high power applications (correct)

How many terminals does a Silicon Controlled Rectifier have?

4 terminals
2 terminals
3 terminals (correct)
5 terminals

What type of semiconductor layers make up a Silicon Controlled Rectifier?

Three layers of n-type material
Four alternating layers of p-type and n-type materials (correct)
One layer of a composite semiconductor
Two layers of p-type material

Which of the following terms is often used interchangeably with Silicon Controlled Rectifier?

Thyristor (B) Signup and view all the answers

Who led the team of power engineers that developed the SCR?

Gordon Hall (D) Signup and view all the answers

What are the three terminals of a silicon controlled rectifier?

Anode, Cathode, Gate (C) Signup and view all the answers

In which region of the V-I characteristics does the SCR not conduct electric current?

Forward blocking region (C) Signup and view all the answers

Which junctions are forward biased in the Forward Blocking Mode?

Junctions J1 and J3 (C) Signup and view all the answers

What happens when the SCR reaches the forward breakdown voltage (VBF)?

Current flow increases rapidly. (B) Signup and view all the answers

What happens when a positive voltage is applied to the gate terminal?

SCR can conduct current with lower anode-cathode voltage (C) Signup and view all the answers

What defines the reverse blocking region in an SCR?

Negative voltage on the anode and positive voltage on the cathode. (D) Signup and view all the answers

In which mode does the SCR exhibit high resistance and prevents current flow despite being forward biased?

Forward Blocking Mode (B) Signup and view all the answers

What is the primary role of a TRIAC?

To control AC loads. (A) Signup and view all the answers

How does a TRIAC operate when MT2 is at a positive potential relative to MT1?

Current flows through P1-N1-P2-N2. (C) Signup and view all the answers

What phenomenon allows the SCR to conduct current during Forward Conducting Mode?

Minority carriers gaining energy and causing junction breakdown (C) Signup and view all the answers

What is the role of the external resistance in a TRIAC circuit?

To limit the excess current (D) Signup and view all the answers

In which modes does a TRIAC conduct?

In both positive and negative half cycles (C) Signup and view all the answers

What is the primary characteristic of a DIAC?

It conducts in both directions above break over voltage (C) Signup and view all the answers

Which of the following is a disadvantage of using a TRIAC?

Less reliable compared to SCR (C) Signup and view all the answers

What is a primary application of a DIAC?

Triggering other devices like TRIACs (B) Signup and view all the answers

Which statement about the V-I characteristics of a DIAC is true?

The graph forms a shape of letter 'Z' (D) Signup and view all the answers

How does a DIAC switch from off-state to on-state?

When applied voltage exceeds break over voltage (C) Signup and view all the answers

What happens to junction J2 during forward voltage triggering when the forward break over voltage is reached?

It starts conducting huge current. (B) Signup and view all the answers

Which triggering method uses a light source to activate the SCR?

Light Triggering (C) Signup and view all the answers

What is a critical drawback of using forward voltage triggering in SCR operation?

It can lead to thermal runaway and damage. (C) Signup and view all the answers

Which mode of SCR operation occurs when the anode is negative and the cathode is positive?

Reverse Blocking Mode (B) Signup and view all the answers

What triggers the SCR in the dt/dv method?

A sharp increase in voltage over time. (A) Signup and view all the answers

What phenomenon may occur due to temperature increase in an SCR?

Increase in number of electron-hole pairs. (B) Signup and view all the answers

Which SCR triggering method is considered the most reliable?

Gate Triggering (A) Signup and view all the answers

What should happen to the gate voltage after the SCR is turned ON?

It should be removed. (A) Signup and view all the answers

What is the impact of spurious voltage spikes on SCRs?

They can induce unwanted triggering. (D) Signup and view all the answers

What is the primary function of a DIAC in a circuit?

To trigger TRIACs for symmetrical switching (D) Signup and view all the answers

Which statement accurately describes the operation of a DIAC?

It triggers when voltage exceeds a specific threshold in either direction (A) Signup and view all the answers

How does the two transistor analogy of SCR work?

It depicts SCR as connected two transistors with feedback through current control (B) Signup and view all the answers

What happens to the SCR after it is triggered?

It remains in the conducting state until the anode current drops below a threshold (C) Signup and view all the answers

What characteristic of DIAC helps in reducing harmonics in a system?

Symmetrical switching characteristics (C) Signup and view all the answers

Which of the following is a disadvantage of using a DIAC?

It only conducts when voltage exceeds 30 volts (B) Signup and view all the answers

What role does the gate current play in SCR operation?

It triggers the SCR into conduction (D) Signup and view all the answers

What does the regeneration process in SCR do after triggering?

Reinforces the triggering effect and maintains conduction (C) Signup and view all the answers

Which factor is critical for the reliable turn-on of an SCR?

Timing and level of the gate triggering signal (A) Signup and view all the answers

Silicon Controlled Rectifier (SCR)

A 3-terminal, 4-layer semiconductor device used to control high power.

SCR's Layers

SCR is made of alternating semiconductor layers (P and N type).