Do We Use Ac Or Dc:Interesting Aspects on Different Industries and Home

Electricity has two forms: alternating current AC and direct current DC, so there is always a comparison between AC or DC, Tesla has supported AC where Edison has supported the DC mode of electricity.

Although alternating current AC is comparatively more used than that of DC, this article will discuss where do we use AC or DC in different aspects.

Uses of Alternating Current:

Alternating Current (AC) has its benefits as well as drawbacks. There are different applications where AC is used over DC as per the requirement of operation.

Power Adaptors
Image Credit: “Power Adaptors” by schoschie is licensed under CC BY 2.0

Let’s discuss where do we use ac or dc, The following is where the AC power supply is used :

  • Alternating current is generally used in industry for transmission and generation of electricity as the generation of alternating current (AC) is much easier than that of Direct Current (DC) for high voltages, as AC has better efficiency than DC.
  • DC loses more power to heat relative to AC which causes a higher risk of producing fire, burning appliances, high-cost maintenance and complicated conversion between high voltage and low current to low voltage and high current in DC using Transformers, so in place of DC most industry prefers AC.
  • In the household, there are many appliances that convert electrical energy into mechanical energy that devices use AC power supply such as dishwasher, refrigerator, washing machine, etc.
  • The AC motor (uses AC as power supply) depends on the reversing magnetic field produced by alternating current. The DC motor requires brushes to make electrical contact with the moving coil. In contrast, an AC motor does not require it, which makes AC to operate AC motors easily.
  • Generally, all kind of transformer uses AC supply as DC supply does not work with transformers. The DC Transformer is there but designing that kind of transformer is complicated than a regular transformer.
  • AC induction motors are used for large-sized industrial Servo Motors, which often require variable frequency drives to allow control of their speed.
  • High Voltage AC is more efficient than DC for sending electricity over a considerable distance; that is why high voltages from power plants are supplied to the home, which can be easily converted to required voltage or current by using a transformer.
  • An induction motor or heater uses AC as supply; if DC supply is used in induction motor, commutator and brush will be required as extra part in motor, which will wear out very easily the motor. The need for the replacement of the brush or commutator will be very much frequent. Using the AC in the induction motor makes the overall cost less, the motor will last longer. Maintenance will not be required as a DC induction motor. As for induction heating, the heat is generated by Eddy current, which requires an alternating current eddy current that is not present in DC.
  • The air conditioner uses AC as a supply instead of DC, and there is some air conditioner that uses DC, but that air conditioner has Limited power applications. Although the Air conditioner uses DC, the main supply is always an AC supply. The inverter of the Air conditioner converts the AC to DC then uses it.
  • For home and residential applications, only a single-phase AC power supply is used. A three-phase AC supply is used as 3 phase supply for commercial and industrial facilities to accommodate high loads better. A single-phase AC supply is used when loads are lighting or heating, and a three-phase AC supply is used for large machines for electric motors.
  • The power factor of 3 phase AC motors is high, which means they require less voltage for the load. The motor that uses a three-phase can start with only a power supply. It can even reverse its direction if needed, whereas the motor that uses a single-phase AC cannot start itself; they require an external power supply or device for starting it.
  • Use of AC Motors is preferred for Air Conditioning compressor, power drives, hydraulic and irrigation pump etc.
  • The airline industry uses AC as the main electrical power supply over DC supply. If needed, the AC will be converted to DC using a transformer rectifier unit for the airline. The engine-driven alternator supplies containers powered to AC essentials by an AC bus, where some large turboprops have both AC or DC generators.
  • 3 phase synchronous motor is used for application which needs operating at constant speed such as air compressor motor-generator Rolling Mills paper and cement industry etc
  • Single-phase synchronous motor is used in clocks teleprinters and every kind of timing device, recording instrument, sound recording and reproducing instrument.

Use of Direct Current:

Direct current also has its benefits as well as drawbacks. There are different applications where DC is used over AC because of its efficiency or the specific operation’s requirement.

Batteries
Image Credit: “Batteries” by spatulated is licensed under CC BY 2.0

Here are the following where DC supply is used :

  • Different devices or appliances (mainly digital electronic appliances) at home use DC as a supply, such as a microwave oven, computer, phone, etc.
  • DC has better transmission than AC due to laser losses in AC
  • DC is mainly used with appliances that use batteries. Every charger adaptor used in our houses is a converter from AC to DC, such as phone chargers, flashlight chargers, televisions, computers, hybrid or electric verticals, etc.
  • DC is generally used for long-distance transmission. As the transmission of AC power is very much Limited to short or medium range distance maximum distance, AC power cover is 800 km approximately.
  • High voltage DC has better transmission than AC due to laser losses in AC.
  • For local generation DC is much better than that of AC as conversion between AC to DC is expensive.
  • Both rechargeable and non-rechargeable types of battery supplies are always DC rechargeable battery need DC for recharge.
  • Currents generated from solar panels are the DC units of solar panels; an inverter is used to enable DC to AC conversion.
  • Where stable speed torque or operation is required, the steady energy flow of DC is used for operation off Motors.
  • DC motor is used for steel mill rolling equipment, paper machine, etc.
  • Series DC motors are used for heavy-duty applications such as electric locomotives, lifts, cranes, Steel Rolling Mills etc.
  • DC shunt motor is used for operating appliances or devices at constant speed such as vacuum cleaners, woodworking machines, conveyors, elevators, grinders, shafts, small printing presses etc.

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