Alternating current - Revision history

Jnc: Move 3-phase stuff to separate article

2024-08-15T17:36:12Z

Move 3-phase stuff to separate article

Jnc: Cover 3-phase

2024-08-15T12:28:46Z

Cover 3-phase

Jnc: +cat

2018-12-14T00:54:56Z

+cat

Jnc: Proper cat

2018-10-18T14:24:57Z

Proper cat

Jnc: Mention frequency

2018-07-15T04:02:03Z

Mention frequency

Jnc: A good start

2018-04-29T13:11:39Z

A good start

New page

'''Alternating current''' (often abbreviated as '''AC''') refers to the [[voltage]] (and thus [[current]]) pattern used in one of the two main methods of carrying power (the other being so-called [[direct current]], or DC).

In AC, The voltage starts at zero, increases to a positive peak, levels off, returns to zero, then goes negative, reaches a nagative peak, levels off again, and then returns to zero; the cycle then repeats the sinusoidal pattern.

AC is preferred over DC for power transmission since i) [[resistor|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.

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 AC is preferred over DC for power transmission since i) [[resistor|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), so high voltages are preferred for transmission of power, and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.
-AC used for powering heavy equipment (especially rotating equipment) is often supplied in '3-phase' form; i.e. there are a trio of supply [[conductor]]s, each of which carries power in a different [[phase]]. (The three phases differ by 120 degrees.) This allows the torque produced in an electric motor to be 'smoother' - in a motor powered by single-phase AC, the torque output will necessarily be sinusoidal, like the input voltage.
+AC used for powering heavy equipment (especially rotating equipment) is often supplied as [[three-phase power]].
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 [[Category: Electrical Basics]]

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 '''Alternating current''' (often abbreviated as '''AC''') refers to the [[voltage]] (and thus the [[current]]) pattern used in one of the two main methods of carrying power (the other being so-called [[direct current]], or DC).
-In AC, the voltage starts at zero, increases to a positive peak, levels off, returns to zero, then goes negative, reaches a nagative peak, levels off again, and then returns to zero; the cycle then repeats the sinusoidal pattern. The speed of this alteration is the [[frequency]] of the alternating current.
+In AC, the voltage starts at zero, increases to a positive peak, levels off, returns to zero, then goes negative, reaches a negative peak, levels off again, and then returns to zero; the cycle then repeats the sinusoidal pattern. The speed of this alteration is the [[frequency]] of the alternating current.
 AC is preferred over DC for power transmission since i) [[resistor|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), so high voltages are preferred for transmission of power, and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.
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 [[Category: Electrical Basics]]

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	AC is preferred over DC for power transmission since i) [[resistor\|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), so high voltages are preferred for transmission of power, and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.		AC is preferred over DC for power transmission since i) [[resistor\|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), so high voltages are preferred for transmission of power, and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.

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-'''Alternating current''' (often abbreviated as '''AC''') refers to the [[voltage]] (and thus [[current]]) pattern used in one of the two main methods of carrying power (the other being so-called [[direct current]], or DC).
+'''Alternating current''' (often abbreviated as '''AC''') refers to the [[voltage]] (and thus the [[current]]) pattern used in one of the two main methods of carrying power (the other being so-called [[direct current]], or DC).
-In AC, The voltage starts at zero, increases to a positive peak, levels off, returns to zero, then goes negative, reaches a nagative peak, levels off again, and then returns to zero; the cycle then repeats the sinusoidal pattern.
+In AC, the voltage starts at zero, increases to a positive peak, levels off, returns to zero, then goes negative, reaches a nagative peak, levels off again, and then returns to zero; the cycle then repeats the sinusoidal pattern. The speed of this alteration is the [[frequency]] of the alternating current.
-AC is preferred over DC for power transmission since i) [[resistor|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.
+AC is preferred over DC for power transmission since i) [[resistor|resistive]] losses are reduced when power is transmitted at high voltages (since resistive losses go as I^2*R), so high voltages are preferred for transmission of power, and ii) [[transformer]]s are simple, passive devices which can easily convert high voltages down to the safer low voltages better for actual use and consumption - but transformers only work with AC.