Auto Selection of any Available Phase, in 3 Phase Supply System

1
Auto Selection of any Available Phase, in 3 Phase
Supply System
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Auto Selection of any Available Phase, in 3 Phase
Supply System

• Introduction
• The basic idea for the development of the project
  is to provide supply to the single phase load if
  any of the phases, out of the 3 phases misses.
• The three transformers are connected to the 3
  phases supply. It automatically switch to next
  phase while one phase is misses.
• For monitoring the phase shifting we are using
  NAND gate logics.
• The relay driver IC to change the load to the
  next phase through the contacts those are fed
  from all the three phases.
• At final condition it works on inverter.

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3
Auto Selection of any Available Phase, in 3 Phase
Supply System

• Working
• Three phase supply are given to three independent
  transformers connected in together with another
  transformers from receiving supply, an inverter.
• The secondary of the transformers are used to
  develop DC by half wave rectification and then
  deriving four number of opto isolators
  individually.
• The DC supply from all the three phases and
  inverter supply are combined and then fed to the
  regulator IC 7805 for the circuit operation
  power.
• The relays connected drive the load with
  interlocking logic from the NO/NC contact such
  that the 1st phase load automatically changes
  over to any available phase in the event

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4
Auto Selection of any Available Phase, in 3 Phase
Supply System

• Description of power supply
• The basic idea for the development of the project
  is to provide supply to the single phase load if
  any of the phases, out of the 3 phases misses.
• The three transformers are connected to the 3
  phases supply.
• It automatically switch to next phase while one
  phase is misses.
• For monitoring the phase shifting we are using
  NAND gate logics.
• The relay driver IC to change the load to the
  next phase through the contacts those are fed
  from all the three phases.
• At final condition it works on inverter.

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5
Auto Selection of any Available Phase, in 3 Phase
Supply System

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Auto Selection of any Available Phase, in 3 Phase
Supply System

• Hardware Requirements
• Transformers
• Logic Gates
• Resistors
• Capacitors
• Relay Driver
• Relays
• Lamp
• Diodes

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7
Auto Selection of any Available Phase, in 3 Phase
Supply System

• And Gate description
• The 4000 Series CMOS range, and contains four
  independent CMOS AND gates each with two inputs.
• Pin Description
• Pin 7 is the negative supply
• Pin 14 is the positive supply
• Pins 12, 56, 89, 1213 are gate inputs
• Pins 3, 4, 10, 11 are gate outputs

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8
Auto Selection of any Available Phase, in 3 Phase
Supply System

• Relay
• A relay is an electrically operated switch.
• Current flowing through the coil of the relay
  creates a magnetic field which attracts a lever
  and changes the switch contacts.
• The coil current can be on or off so relays have
  two switch positions and have double throw
  (changeover) switch contacts as shown in the
  diagram.

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9
Auto Selection of any Available Phase, in 3 Phase
Supply System
Resistor
Capacitors

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10
Auto Selection of any Available Phase, in 3 Phase
Supply System

• Relay driver
• The ULN2003 is a monolithic high voltage and high
  current Darlington transistor arrays.
• It consists of seven NPN Darlington pairs that
  features high-voltage outputs with common-cathode
  clamp diode for switching inductive loads.
• The ULN functions as an inverter.
• If the logic at input 1B is high then the output
  at its corresponding pin 1C will be low.

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Auto Selection of any Available Phase, in 3 Phase
Supply System

• Applications
• In this work, an automatic three phase changer
  comparator has been designed, built and tested.
• The system operates smoothly as expected. It is
  reliable, durable and portable. The cost involved
  in developing it, makes it much more affordable
  than comparable product.

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Auto Selection of any Available Phase, in 3 Phase
Supply System

• Conclusion
• Further the project can be enhanced by
  incorporating power semiconductor devices such as
  thyristors/IGBTs for instantaneous changeover to
  the next available phase.
• This overcomes the drawback of the changeover
  time generally witnessed by relay switching
  operations.

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