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Do-It-Yourself Kit (recommended)

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With an Assembled & Tested PCB

DIY kit comes with an Assembled and Tested PCB ensuring 100% output guarantee. Includes hardware for assembling project from scratch. Fully supported by elaborate documentation, audio visuals and tools to independently carry out the project work.

PROJECT DESCRIPTION

The three-phase induction motor draws current more than its rated capacity during its starting state which may lead to the damage of windings of the motor. In order to avoid this problem, for the smooth and soft start of the induction motor  (for safer operation), voltage is gradually applied from lower to higher state.

The main intention of this project is the designingof a smooth start process for the three-phase induction motorby applying the delayed pulses to the motor through the  SCR. The motor thus starts slowly, and then picks-up full speed.

The smooth starting of the induction motor is achieved by the SCR-firing-angle-control principle.This project consists of six-anti-parallel SCRs connected in series with an induction motor to the mains supply, wherein two for each phase is used. Opto-coupler is connected to trigger the back-to-back SCRs with isolation from the controlling section. During the start, the firing angle is heavily delayed by receiving delayed triggering pulses from the operational amplifier. One op-amp operating in comparator mode develops zero voltage pulses to generate sawtooth-voltage waveforms.This waveform is further compared against a varying voltage by charging and discharging a capacitor during the start to develop delayed pulses for triggering the SCRs. A lamp is provided in this project instead of an induction motor for demonstration purposes.

This project in future can be implemented by using IGBTs in place of SCRs with PWM control to reduce the harmonic distortions often encountered in the SCR-triggering mechanism.

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The three-phase induction motor draws current more than its rated capacity during its starting state which may lead to the damage of windings of the motor. In order to avoid this problem, for the smooth and soft start of the induction motor  (for safer operation), voltage is gradually applied from lower to higher state.

The main intention of this project is the designingof a smooth start process for the three-phase induction motorby applying the delayed pulses to the motor through the  SCR. The motor thus starts slowly, and then picks-up full speed.

The smooth starting of the induction motor is achieved by the SCR-firing-angle-control principle.This project consists of six-anti-parallel SCRs connected in series with an induction motor to the mains supply, wherein two for each phase is used. Opto-coupler is connected to trigger the back-to-back SCRs with isolation from the controlling section. During the start, the firing angle is heavily delayed by receiving delayed triggering pulses from the operational amplifier. One op-amp operating in comparator mode develops zero voltage pulses to generate sawtooth-voltage waveforms.This waveform is further compared against a varying voltage by charging and discharging a capacitor during the start to develop delayed pulses for triggering the SCRs. A lamp is provided in this project instead of an induction motor for demonstration purposes.

This project in future can be implemented by using IGBTs in place of SCRs with PWM control to reduce the harmonic distortions often encountered in the SCR-triggering mechanism.

PROJECT HIGHLIGHTS
Non-Microcontroller Project.
Solid State Soft Starter.
Call/mail for Tech Support from 10 am - 7 pm IST.
Easy to use, Self-explanatory kit.
All-inclusive solution kit.
Extensive audio-visuals available.
Branding-free material.
Pre-programmed Microcontroller.
×
Non-Microcontroller Project.
Solid State Soft Starter.
Call/mail for Tech Support from 10 am - 7 pm IST.
Easy to use, Self-explanatory kit.
All-inclusive solution kit.
Extensive audio-visuals available.
Branding-free material.
Pre-programmed Microcontroller.
BLOCK DIAGRAM
Hardware Requirements
  • Op-amps as comparators
  • Opto-isolators
  • Thyristors
  • Transistors
  • Regulator
  • Diodes
  • Transformers
  • Resistors
  • Capacitors
  • LEDs
  • Lamps
×
  • Op-amps as comparators
  • Opto-isolators
  • Thyristors
  • Transistors
  • Regulator
  • Diodes
  • Transformers
  • Resistors
  • Capacitors
  • LEDs
  • Lamps
Q & A
Q:  What is the three phase induction motor rating to be used?
A:  Three phase induction motor can be used, but limited up to 1 HP only as it uses a relay of 6A contact rating only. For higher HP just use a contactor of appropriate rating. The 230 AC coil of the contactor is powered in series from one of the contacts of the relay.
Q:  What is soft start?
A:  Gradually increasing the supply voltage to the motor is called soft start
Q:  Why bulb is used instead of motor?
A:  In order to visualize the soft start it is better to use a bulb.
Q:  What is the rating of motor to be used in this project?
A:  A 3 phase ¼ HP motor is used in this project.
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