The Differences will be discussed through the following terms:
Definition
symbol
Frequency
Waveform
Magnitude
Power
Terminals
Polyphase System
Source
Applications
DEFINITIONS OF AC & DC POWER
“ACstands for Alternating Current. ACpower continuously changes with respect to the time, It also changes its direction at fixed intervals. “
“DCstands for Direct Current. DC power remains constant throughout the time, It always follow one single direction.”
Both the powers 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 power 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 power frequency standard is 50Hz Which means 50 cycles per second.
Since DC power is stable not changing its direction with respect to time. DC has No cycle; No frequency.
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 does not contains any 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 power 120VDC as an input While AC indoor unit take 230VAC power 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 power; which is moving with time; is time dependent. While DC power 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 does not exist in DC; It exist in AC only because it is AC which is moving with the time, Changing with the time.
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.
All type of moving vehicles which are equipped with batteries contains these type of DC generators. These generators are mechanically connected with the engine. Engines while running moves these generators which further produces the DC power to charge the batteries.
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 power.
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 power into DC power 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
Power full Electrical machines such that Generators, Motors & Transformers all are working on the principle of faraday law of mutual induction. Faraday law of mutual induction is only possible due to the Alternating current.
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 power varies over time, changing direction and frequency, while DC power remains constant in one direction. The summary contrasts AC’s multiple waveforms with DC’s stability, along with their power calculations, which involve voltage and current factors. Applications vary greatly, with AC powering large machines and DC commonly used in electronics and batteries. Sources for both power types are outlined, including alternators for AC and generators for DC.
Ac & Dc power, Both the powers 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 !
