Alternating current and direct current - Revision history

Designing Buildings at 10:38, 30 August 2021

2021-08-30T10:38:04Z

← Older revision		Revision as of 10:38, 30 August 2021
Line 51:		Line 51:
	* PV inverter.		* PV inverter.
	* Renewable energy.		* Renewable energy.
		+	* Single-phase v three-phase ac current systems.
	* Solar photovoltaics.		* Solar photovoltaics.
	* The future of UK power generation.		* The future of UK power generation.

Designing Buildings at 07:10, 28 December 2020

2020-12-28T07:10:19Z

← Older revision		Revision as of 07:10, 28 December 2020
Line 56:		Line 56:
	* Watt.		* Watt.

−	[[Category:~~Theory~~]] [[Category:~~Products_/_components~~]] [[Category:~~DCN_Product_Knowledge~~]]	+	[[Category:DCN_Definition]] [[Category:Definitions]] [[Category:Theory]] [[Category:Products_/_components]]

Designing Buildings at 15:49, 4 February 2019

2019-02-04T15:49:54Z

← Older revision		Revision as of 15:49, 4 February 2019
Line 1:		Line 1:
	{\|		{\|
−	~~\|width="100%"\|~~	+	\| [[File:Ac-supply.png\|link=File:Ac-supply.png]]
−	{\|	+
−	\| [[File:Ac-supply.png]]	+
	\|-		\|-
	\| The sinusoidal curve that represents the positive and negative phases of AC current.		\| The sinusoidal curve that represents the positive and negative phases of AC current.
	\|}		\|}
−	\|}	+
		+	= Introduction =

	An electric current is a flow of charge along a conductor, such as a copper wire. When it flows in one direction it is called direct current (DC). When it reverses direction periodically it is termed an alternating current (AC).		An electric current is a flow of charge along a conductor, such as a copper wire. When it flows in one direction it is called direct current (DC). When it reverses direction periodically it is termed an alternating current (AC).
Line 16:		Line 15:
	AC current operates in the following way: it will start from a position of zero, build up to its maximum value (top of the positive peak on the sinusoidal curve), reverse to zero, continue to the maximum in the opposite direction (negative, below the x-axis) then reverse back to zero, upon which the cycle begins again. The number of these cycles performed per second is called the frequency and is measured in hertz (Hz).		AC current operates in the following way: it will start from a position of zero, build up to its maximum value (top of the positive peak on the sinusoidal curve), reverse to zero, continue to the maximum in the opposite direction (negative, below the x-axis) then reverse back to zero, upon which the cycle begins again. The number of these cycles performed per second is called the frequency and is measured in hertz (Hz).

−	Domestic and commercial power in the UK and other countries is typically of low frequency (50-60Hz). Far higher frequencies are encountered in other applications such as television (100,000,000 cycles/second (100 megahertz (or 100MHz) where 1MHz is one million cycles/second)). Even higher frequencies of several thousand megahertz are used in microwave and radar applications, while in ~~cell~~ phones they may be in the order of around 1,000MHz (one thousand million hertz or 1 gigahertz (GHz).	+	Domestic and commercial power in the UK and other countries is typically of low frequency (50-60Hz). Far higher frequencies are encountered in other applications such as television (100,000,000 cycles/second (100 megahertz (or 100MHz) where 1MHz is one million cycles/second)). Even higher frequencies of several thousand megahertz are used in microwave and radar applications, while in mobile phones they may be in the order of around 1,000MHz (one thousand million hertz or 1 gigahertz (GHz).

−	~~Electronic~~ devices contain semi-conductors which require low-voltage DC. This means that such devices must convert high voltage AC to low voltage DC. This is usually achieved by the plug-in power plug that is supplied with the device	+	Many electronic devices contain semi-conductors which require low-voltage DC. This means that such devices must convert high voltage AC to low voltage DC. This is usually achieved by the plug-in power plug that is supplied with the device.

	= Some advantages of AC over DC =		= Some advantages of AC over DC =
Line 24:		Line 23:
	AC current offers numerous benefits over DC. Typically, these include:		AC current offers numerous benefits over DC. Typically, these include:

−	* AC can be relatively easily and economically stepped up or down with a transformer to suit the application. DC cannot be wired through a transformer	+	* AC can be relatively easily and economically stepped up or down with a transformer to suit the application. DC cannot be wired through a transformer.
−	* Because it can be stepped up (and down), AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use	+	* Because it can be stepped up (and down), AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use.
−	* High voltages can be generated in AC. This is more difficult with DC	+	* High voltages can be generated in AC. This is more difficult with DC.
−	* Because of the high voltages that can be generated, AC can be transmitted over long distances	+	* Because of the high voltages that can be generated, AC can be transmitted over long distances.
−	* Long-range transmission results in relatively low energy losses resulting from resistance	+	* Long-range transmission results in relatively low energy losses resulting from resistance.
−	* AC is cheaper to generate than DC	+	* AC is cheaper to generate than DC.
	* AC can be easily converted to DC if required.		* AC can be easily converted to DC if required.
		+
		+	= DC networks =
		+
		+	The Energy Saving Trust estimated in 2007 that by 2020, 45% of the electricity consumption in a household would be entertainment, computers and gadgets and LED lighting, all of which are DC-powered. This, in combination with the emergance of DC generation from solar panels, and battery storage, have given rise to the concept of DC (rather than AC) networks.
		+
		+	For more information see: DC electricity networks.

	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =

		+	* DC electricity networks.
	* Electricity supply.		* Electricity supply.
	* Energy consumption.		* Energy consumption.
Line 43:		Line 49:
	* Oil - a global perspective.		* Oil - a global perspective.
	* Power.		* Power.
		+	* PV inverter.
	* Renewable energy.		* Renewable energy.
	* Solar photovoltaics.		* Solar photovoltaics.
Line 49:		Line 56:
	* Watt.		* Watt.

−	[[Category:Theory]] [[Category:Products_/_components]]	+	[[Category:Theory]] [[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]

Editor at 18:48, 1 February 2019

2019-02-01T18:48:26Z

← Older revision		Revision as of 18:48, 1 February 2019
Line 1:		Line 1:
		+	{\|
		+	\|width="100%"\|
	{\|		{\|
	\| [[File:Ac-supply.png]]		\| [[File:Ac-supply.png]]
		+	\|-
		+	\| The sinusoidal curve that represents the positive and negative phases of AC current.
		+	\|}
	\|}		\|}

Line 21:		Line 26:
	* AC can be relatively easily and economically stepped up or down with a transformer to suit the application. DC cannot be wired through a transformer		* AC can be relatively easily and economically stepped up or down with a transformer to suit the application. DC cannot be wired through a transformer
	* Because it can be stepped up (and down), AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use		* Because it can be stepped up (and down), AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use
−	* Compared to DC, AC transmitted over long distances results in relatively low energy losses from resistance
−	* AC is cheaper to generate than DC
	* High voltages can be generated in AC. This is more difficult with DC		* High voltages can be generated in AC. This is more difficult with DC
−	* ~~Generating~~ AC ~~is cheaper than generating DC~~	+	* Because of the high voltages that can be generated, AC can be transmitted over long distances
−	* AC ~~induction motors are simpler and~~ cheaper~~, requiring less maintenance~~ than ~~their~~ DC ~~counterparts~~	+	* Long-range transmission results in relatively low energy losses resulting from resistance
		+	* AC is cheaper to generate than DC
	* AC can be easily converted to DC if required.		* AC can be easily converted to DC if required.

Line 44:		Line 48:
	* Types of fuel.		* Types of fuel.
	* Watt.		* Watt.
		+
		+	[[Category:Theory]] [[Category:Products_/_components]]

Editor: Created page with "{| | File:Ac-supply.png |} An electric current is a flow of charge along a conductor, such as a copper wire. When it flows in one direction it is called direct current (DC)...."

2019-02-01T18:43:27Z

Created page with "{| | File:Ac-supply.png |} An electric current is a flow of charge along a conductor, such as a copper wire. When it flows in one direction it is called direct current (DC)...."

New page

{|
| [[File:Ac-supply.png]]
|}

An electric current is a flow of charge along a conductor, such as a copper wire. When it flows in one direction it is called direct current (DC). When it reverses direction periodically it is termed an alternating current (AC).

AC current is generally used to power homes and businesses, and is also present when audio and radio signals are carried on electrical wires. DC current is typical of batteries that power flashlights and other home appliances and is also used in some industrial applications.

Because AC current reverses direction periodically, it can be characterised by a sinusoidal waveform where the half periods above the x-axis represent the positive phase of the current and the half periods below the x-axis represent the negative phase.

AC current operates in the following way: it will start from a position of zero, build up to its maximum value (top of the positive peak on the sinusoidal curve), reverse to zero, continue to the maximum in the opposite direction (negative, below the x-axis) then reverse back to zero, upon which the cycle begins again. The number of these cycles performed per second is called the frequency and is measured in hertz (Hz).

Domestic and commercial power in the UK and other countries is typically of low frequency (50-60Hz). Far higher frequencies are encountered in other applications such as television (100,000,000 cycles/second (100 megahertz (or 100MHz) where 1MHz is one million cycles/second)). Even higher frequencies of several thousand megahertz are used in microwave and radar applications, while in cell phones they may be in the order of around 1,000MHz (one thousand million hertz or 1 gigahertz (GHz).

Electronic devices contain semi-conductors which require low-voltage DC. This means that such devices must convert high voltage AC to low voltage DC. This is usually achieved by the plug-in power plug that is supplied with the device

= Some advantages of AC over DC =

AC current offers numerous benefits over DC. Typically, these include:

* AC can be relatively easily and economically stepped up or down with a transformer to suit the application. DC cannot be wired through a transformer
* Because it can be stepped up (and down), AC can be increased to high voltage levels for transmission over large distances, then stepped down to safer levels for consumer use
* Compared to DC, AC transmitted over long distances results in relatively low energy losses from resistance
* AC is cheaper to generate than DC
* High voltages can be generated in AC. This is more difficult with DC
* Generating AC is cheaper than generating DC
* AC induction motors are simpler and cheaper, requiring less maintenance than their DC counterparts
* AC can be easily converted to DC if required.

= Related articles on Designing Buildings Wiki =

* Electricity supply.
* Energy consumption.
* Energy storage.
* Fossil fuel.
* Hydroelectricity.
* Micro-grids.
* Microgeneration.
* Oil - a global perspective.
* Power.
* Renewable energy.
* Solar photovoltaics.
* The future of UK power generation.
* Types of fuel.
* Watt.