The Differences will be discussed through the following terms:
Definition
symbol
Frequency
Waveform
Magnitude
Power
Terminals
Polyphase System
Source
Applications
DEFINITIONS OF AC & DC SUPPLY
“ACstands for Alternating Current. AC supply continuously changes with respect to the time, It also changes its direction at fixed intervals. “
“DCstands for Direct Current. DC supply remains constant throughout the time, It always follow one single direction.”
Both the supplies shown below through a GIF :
Sinusoidal waveform of Alternating current
GIF shows DC waveform
SYMBOL
An collage images of a clamp-meter is shown below. Which shows the symbol of both AC & DC.
DC Symbol
AC Symbol
FREQUENCY
As discussed above, AC supply continuously changes with respect to the time. Changes from one direction to another. If we consider the AC GIF above, Sinusoidal waveform moves from positive to negative; One half waveform in positive & second half wave in negative. In together; Both the halves constitute ACycle.
Frequency represents number of cycles per second & its unit are Hz. In India, AC supply frequency standard is 50Hz Which means 50 cycles per second.
Since DC supply is stable not changing its direction with respect to time. DC quantity has a frequency of 0 Hz.
WAVEFORM
DC always remains constant & Fixed; While AC is moving & changing. That’s Why AC has multiple waveforms like sinusoidal waveform & triangular waveform.
While DC contains stable or pulsating waveform. A Triangular AC waveform shown below:
Triangular AC Waveform
MAGNITUDE
Two images been shown below which shows the input voltage rating of the machines.
1. 7.5KVA inverter having input voltage 120V DC.
2. Name plate of AC indoor unit by DAIKIN having a voltage 230V AC.
7.5KVA Inverter (DC input Voltage 120V DC | AC output voltage 230V AC)
Name plate of AC indoor unit by DAIKIN Voltage 230VAC
Inverter take DC supply 120VDC as an input While AC indoor unit take 230VAC supply as an input.
If we consider the DC waveform which remains constant throughout the time, It is easy to consider the level of the waveform(Vmax) because it is not moving like wise in AC. Now the question is, What do we consider in AC waveform.
A GIF of DC voltage is shown below. It is been clearly seen voltage magnitude remains constant throughout the time. That magnitude represent the maximum level.
GIF shows Constant magnitude in DC
A GIF of AC voltage is shown below. It is been clearly seen that waveform is moving with respect to time from positive axis to negative axis. In positive & in negative axis, Waveform attains its maximum level for only 2 times.
Gif shows changing magnitude of AC
“In AC, RMS value been considered as a magnitude. RMS stands for ROOT MEAN SQUARE !”
It is the Root mean of instantaneous squared values of half waveform.
RMS value of an AC produces the same amount of heat As do DC of same magnitude produces while flowing through the same resistance.
AC waveform marked with instantaneous values shown below.
RMS value of AC waveform | Vrms= √[(x0²+x1²+x2² . .+xn²)/n]
POWER
Whether it is DC or AC, Power in both the systems depend upon voltage & current. BUT AC supply; which is moving with time; is time dependent. While DC supply is time independent.
So the power for both system becomes:
P(AC)= Voltage*Current*Power Factor= V*I*cosΦ
P(DC)= Voltage*Current= V*I
(Where cosΦ is the cosine angle between voltage & Current)
Polyphase represents multiple phases with same potential/magnitude. But all the phases are unique & different from each other. Polyphase system exist in AC only because it is AC which is moving with the time, Changing with the time. A steady DC supplydoes not have multiple phases in the same sense as a three-phase AC system.
A 3 phase polyphase system shown through a GIF below :
3 Phase sinusoidal waveform GIF
3 phase polyphase system
Voltage on each phase is known as per phase voltage Which is the voltage between phase & neutral. Let suppose per phase voltage is 230V AC.
Voltage between two phase is known as line to line voltage. If per phase voltage is 230VAC than line to line voltage will be √3*Vph=√3*230=398.37V AC.
3 phase AC power = √3*Voltage*Current*Power factor= √3*V*I*cosΦ
SOURCE
AC SOURCES
Alternator are used to generate the alternating current. Alternator is an Electrical machine which converts mechanical power into electrical power. A basic alternator contains windings on its both rotor & stator.
A mechanical system rotates the rotor which results changing magnetic field links with stator winding. At last, an emf get generated across the stator winding.
DC SOURCES
DC generator
These generators are specially designed to generate direct current. A simple DC generator contains armature moving in between the magnets while an armature is connected to carbon brush mechanism through a commutator arrangement.
DC generators were widely used in older vehicles for battery charging. Modern conventional vehicles generally use alternators, which generate AC and use rectifiers to provide DC for battery charging and the vehicle’s electrical system.
DC generator | Lucas TVS
Batteries
Whatever the type of battery we are talking about whether it is lead acid or lithium ion, All these batteries produces DC supply.
Lithium ion battery|4.2V,2000mAh
LEAD ACID BATTERY | 12V,7AH
Solar cell
Solar cell converts light energy into electrical energy & Energy generated by it; is complete DC.
DC power supply
DC power supplies converts AC supply into DC supply through electronic circuitry. There are multiple types of power supplies which converts single phase AC supply or even a 3 phase AC supply into DC supply.
1.1Amps 24VDC Switched Power Supply
APPLICATIONS
Application of AC
Powerful Electrical machines such that Generators, Motors & Transformers all are working on the principle of faraday law of mutual induction.
“Mutual induction occurs when a changing current produces a changing magnetic flux that links another circuit. AC naturally produces continuous changes in magnetic flux, while DC can also produce mutual induction when its current changes, such as during switching or other transient conditions.”
Application of DC
Total Electronics is working on Direct current.
Batteries
DC motors
SUMMARY
The post discusses the differences between Alternating Current (AC) and Direct Current (DC) across various parameters including definitions, symbols, frequency, waveform, magnitude, power, terminals, polyphase systems, sources, and applications.
AC supply varies over time, changing direction and frequency, while DC supply remains constant in one direction.
Applications vary greatly, with AC powering large machines and DC commonly used in electronics and batteries.
Sources for both supply types are outlined, including alternators for AC and generators for DC.
Ac & Dc supply, Both the supplies work hand in hand. Both are equally important, equally useful.
Hope you like post. If you have any doubt, Suggestion or query please do comments !
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