search
person
Describe triggering circuit for TRIAC using DIAC.

1 Answer

Triggering circuit for TRIAC using DIAC:

DIAC stands for diode alternating current.

It’s a two terminal four layer bidirectional device.

It conducts in both directions.

DIAC is used for triggering TRIAC.

There is no controlling terminal on DIAC.

The figure shows the symbol and V-I characteristics of DIAC.

If the voltage is below VBO the DIAC is in off condition. 

And when the voltage exceeds VBO it comes in ON condition.

Same in both forward and reverse mode.

The figure shows the triggering circuit for TRIAC using DIAC.

The AC input is supplied to load. The load may be a lamp.

Variable resistance in series with a capacitor is connected for controlling the charging of the capacitor.

When the capacitor charges above VBO of DIAC it starts conducting.

The capacitor voltage is applied to TRIAC and it turns ON.

The gate of TRIAC is connected to DIAC.

This series connection of DIAC to the gate terminal of TRIAC reduces the harmonics.


image


image
image

thumb_up_alt 0 like thumb_down_alt 0 dislike

Related questions

Description : Draw symbol & V-I characteristics of (i) LASCR (ii) DIAC (iii) TRIAC

Answer : (i) LASCR:  (ii) DIAC:  (iii) TRIAC: 

Description : With neat diagram explain synchronized UJT triggering circuit.

Answer : Line Synchronized UJT triggering circuit: The UJT is almost ideal as a firing device for SCRs. There are 2 main reasons for the compatibility between UJTs and SCRs. Firstly, the UJT produces a ... , the SCR is sure to have the right polarity between the anode and cathode for turning on.

Description : Describe triggering of SCR using UJT relaxation oscillator. 

Answer : Triggering of SCR using UJT relaxation oscillator: 

Description : Explain triggering of SCR using opto-coupler. State its advantages. 

Answer : Triggering of SCR using opto-coupler:  A simple opto-coupler based triggering circuit for SCR is shown in the figure. An optocoupler or opto-isolator is a combination of light source ... is small size and light weight device. iii)Interfacing with logic circuits is easily possible.

Description : Speed control of the motor using TRIAC

Answer : Speed control of the motor using TRIAC:  This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply. The variable resistor, VR1 is used ... meaning that it may not trigger at the exact same point for each positive and negative half cycle.

Description : Explain the operation of RC triggering circuit with neat diagram.

Answer : RC triggering circuit: The RC half-wave triggering circuit is as shown in the figure. During negative halfcycle of supply voltage vs, the capacitor C charges through diode D2 and load, ... be triggered at 0° & 180° because the supply voltage is zero and less than finger voltage. 

Description : Describe the working principle of Thyristor operated dimmer with the help of circuit diagram.

Answer : Thyristor operated dimmer: A popular thyristor operated dimmer circuit employ TRIAC-DIAC phase control for low AC power control. During each half-cycle, the capacitor charges through (R1+VR1). When the ... time constant {C (R1+VR1)}. Thus by reducing VR1 the lamp brightness can be increased.

Description : Describe the difference between an open circuit and a short circuit.

Answer : Open circuit means the wire is cut meaning power will not flow and close circuit means wire is not cut and hence power will flow.Short circuit is the same as close circuit

Description : Explain the thermal triggering method of SCR. Enlist different triggering methods of SCR.

Answer : Types of Triggering: 1) Forward voltage triggering 2) Thermal triggering (Temperature triggering) 3) Radiation triggering (Light triggering) 4) dv/dt triggering 5) Gate triggering ... generated leakage current increases. This current gets multiplied internally and thyristor is turned on. 

Description : Define triggering. List the type of triggering.

Answer : Triggering: Triggering means turning-ON of a device from its OFF-state.  Types of Triggering: 1) Forward voltage triggering 2) Thermal triggering (Temperature triggering) 3) Radiation triggering (Light triggering) ... (i) D.C. Gate triggering (ii) A.C. Gate triggering (iii) Pulse Gate triggering

Description : Which triggering is the most reliable?

Answer : Gate triggering is most reliable.

Description : With neat sketch explain four modes of operation of a TRIAC? 

Answer : Modes of operation of a TRIAC: There are four different operating modes of TRIAC:  1) MT2 and gate are positive with respect to terminal MT1(Mode1) : Here terminal MT2 is positive ... junction P2-N2 is forward biased, current carriers are injected and therefore, the TRIAC is turned on. 

Description : Compare SCR and TRIAC

Answer : SCR TRIAC It is an unidirectional device. It is a bidirectional device. It is turned-on by only positive gate current. It can be turned-on by either ... applications including lamp dimmer, heating control, zero voltage switched AC relay, small AC motor control etc.

Description : Draw the symbol of GTO and TRIAC.

Answer : 1) GTO: 2) TRIAC: 

Description : SCR is more utilized as compared to Triac because it is

Answer : SCR is more utilized as compared to Triac because it is available with higher ratings

Answer : Yes, we can use triac in the multi-quadrant chopper.

Answer : Yes DIAC can conduct in both direction.

Description : what is DIAC?

Answer : DIAC is a two terminal and four layer device most DIAC have three terminals. DIAC stands for diode for alternating current. It conducts in both direction. It is also used for triggering triac.

Description : Light triggering is mainly used in

Answer : Light triggering is mainly used in High voltage direct current transmission

Description : RC triggering is preferred over resistance triggering because (A) it provides triggering at a precise instant (B) it gives a longer duration gate pulse (C) it enables triggering at a larger value of firing angle (D) it protects the SCR against high dv/dt

Answer : RC triggering is preferred over resistance triggering because it enables triggering at a larger value of firing angle

Description : How do you test a triac?

Description : What is TRIAC?

Answer : TRIAC Structure:  Operating Principle: A triac is a three terminal, five layer semiconductor device. It is equivalent to two separate SCRs connected in anti-parallel with gates common. ... for electric fans and other electric motors. v. Heating control vi. Zero voltage switched relay

Description : Describe the gate circuit for a single phase full converter.

Description : Draw the circuit diagram of battery charger using SCR and explain it’s working.

Answer : Battery charger circuit using SCR: The figure shows the battery charger circuit using SCR. A 12V discharged battery is connected in the circuit and switch SW is closed. The singlephase 230V ... not fired. In this way, after full charging, further charging is automatically stopped.

Description : Explain working of AC circuit breaker using SCR with circuit diagram.

Answer : AC Circuit Breaker:  The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... to non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.

Description : Describe with neat sketch working of hysteresis motor.

Answer : Working: When stator is energized with single phase ac supply, rotating magnetic field is produced because of starting (auxiliary) and main windings, which remain in circuit permanently. The ... the principle of magnetic locking this motor either rotates at synchronous speed or not at all.

Description : State the various lighting calculations methods and Describe any one of them.

Answer : Lighting calculation methods: 1. Lumens or Light flux method 2. Point to point or Inverse Square law method 3. Watts per Square meter method i) Lumens or Light ... is taken according to the illumination desired on an average value considering overall efficiency of the lighting system.

Description : With the help of N-channel JFET describe the effect of input voltage VGS on output current ID.

Answer : Working of N channel FET: * When a voltage is applied between the drain and source with a DC supply (VDD), the electrons flows from source to drain through narrow channel ... where the channel gets completely blocked and the drain current becomes zero is called pinch- off voltage. 

Description : Describe strain gauge with labelled diagram.

Answer : A Strain gauge is a sensor whose resistance varies with applied force. It converts force, pressure, tension, weight, etc., into a change in electrical resistance which can then be measured. When external ... to the applied strain. So, the voltmeter can be calibrated in terms of strain or force. 

Description : Describe the concept of virtual ground with reference to op-Amp.

Answer : Virtual ground concept:-In circuit point A is virtual ground. Figure shows inverting amplifier using op-amp. In this circuit non-inverting terminal is connected to the actual ground. Due to ... zero potential without actually grounding is known as virtual ground concept. Circuit diagram: 

Description : Briefly describe the electric field of a static charge.

Description : Draw and describe working of electronic energy meter.

Answer : working of electronic energy meter:- 1. CT reduces current to reasonable value for current scaling network. 2. Voltage & current scaling networks reduce proportionally the voltage & ... The ADC converts the square wave frequency analog output to display the energy in watthour. 

Description : Describe operation of N-channel JFET

Answer : Operation of N-channel JFET  1) When VGS = 0 volt: When a voltage is applied between the drain and source with a DC supply voltage VDD with VGS = 0 V, the electrons flow from source ... to zero. The gate to source voltage at which current reduces to zero is called as pinch-off voltage.

Description : Describe the various blocks and their functions in pipelined ADC architecture.

Description : Describe the basic SHA operation with the help of its four mode specifications.

Answer : Sample-and-hold amplifier (SHA) is a unity gain amplifier with a mode control switch where the input of the amplifier is connected to a time-varying signal. A trigger pulse at the mode control switch ... but other forms, such as optical and mechanical forms, are possible. Also denoted S/H.

Description : explain blanking times for Bridge circuit?

Answer : Blanking time is provided by driver circuit to power switch. Blanking time is important because the turn on input of one transistor must be delayed with turn off input of another transistor if both ... are connected in one converter leg. This blanking time helps in avoiding cross conduction.

Description : Explain working of static AC circuit breaker. 

Answer : Static AC Circuit breaker: The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.

Description : Draw circuit diagram of symmetrical configuration of bridge converter.

Answer : circuit diagram of symmetrical configuration of bridge converter

Description : Draw circuit diagram of Class B commutation.

Answer : Class B: Resonant Pulse Commutation:

Description : Which circuit is used as amplitude comparator?

Answer : Schmitt trigger circuit is used as amplitude comparator.

Description : What is the use of a thyristor in a circuit?

Description : Explain MOSFET gate drive circuit and totem pole configuration.

Answer : MOSFET gate drive circuit: The turning on and turning off of MOSFET can be controlled from gate to source voltage signal. If the gate to source voltage of MOSFET exceeds threshold ... this configuration, the two switches (transistors) are used in totem pole arrangement with a comparator.

Description : Explain open emitter BJT drive circuit.

Answer : open emitter BJT drive circuit:

Description : Explain DC coupled drive circuit with unipolar output.

Answer : DC coupled drive circuit with unipolar output: The figure shows the circuit and waveforms

Description : Explain thyristor gate drive circuit.

Answer : Thyristor Gate Drive Circuit: The thyristor can be turned on by pulse voltage signal at gate terminal and it does not require continuous drive signal like the transistor. The gate ... circuit provide required minimum gate voltage and gate current then the thyristor conducts properly.

Description : basic gate drive circuit of GTO

Answer : basic gate drive circuit of GTO

Description : Sinusoidal Steady-State Analysis - Using nodal analysis, find node voltages in the circuit.

Answer : Sinusoidal Steady-State Analysis - Using nodal analysis, find node voltages in the circuit.

Description : A parallel RLC circuit has the node equation Determine v(t) using the phasor method.

Answer : A parallel RLC circuit has the node equation Determine v(t) using the phasor method.

Description : A switch tail ring counter is made by using a single D-FF. The resulting circuit is (A) T-FF (B) D-FF (C) SR-FF (D) JK-FF

Answer : A switch tail ring counter is made by using a single D-FF. The resulting circuit is T-FF

Description : The loop equation for a series RLC circuit gives

Answer : The loop equation for a series RLC circuit gives

← Prev Question Next Question →
editAsk a Question
...