Alternating current - Revision history

Jnc: Move 3-phase stuff to separate article

2024-08-15T17:36:12Z

Move 3-phase stuff to separate article

← Older revision		Revision as of 17:36, 15 August 2024
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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.

	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]].

	~~The 3 phases have to be connected to the motor in the correct 'order', or the motor may rotate in the other (i.e. 'wrong') direction. There are stories of large (older) [[disk~~]]~~s, powered by 3-phase power, being connected the wrong way around - with the un-wanted result!~~

	{{semi-stub}}		{{semi-stub}}

	[[Category: Electrical Basics]]		[[Category: Electrical Basics]]

Jnc: Cover 3-phase

2024-08-15T12:28:46Z

Cover 3-phase

← Older revision		Revision as of 12:28, 15 August 2024
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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).		'''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.		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.

			The 3 phases have to be connected to the motor in the correct 'order', or the motor may rotate in the other (i.e. 'wrong') direction. There are stories of large (older) [[disk]]s, powered by 3-phase power, being connected the wrong way around - with the un-wanted result!

	{{semi-stub}}		{{semi-stub}}

	[[Category: Electrical Basics]]		[[Category: Electrical Basics]]

Jnc: +cat

2018-12-14T00:54:56Z

+cat

← Older revision		Revision as of 00:54, 14 December 2018
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			[[Category: Electrical Basics]]

Jnc: Proper cat

2018-10-18T14:24:57Z

Proper cat

← Older revision		Revision as of 14:24, 18 October 2018
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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.

	{{~~Stub~~}}		{{semi-stub}}

Jnc: Mention frequency

2018-07-15T04:02:03Z

Mention frequency

← Older revision		Revision as of 04:02, 15 July 2018
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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.

			{{Stub}}

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.