High Voltage Direct Current

A high-voltage, direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) systems.

Is high voltage AC or DC?

This type of electricity is called a three-phase alternating current. There are two types of AC: one-phase AC and three-phase AC. A three-phase AC is used especially for high-voltage power transmission.

What is considered high voltage for DC?

High voltage is classified as having the potential to cause injury or harm. The ratings of the International Electrotechnical Commission (IEC) consider high voltage to be more than 1,500 volts for DC (direct current) circuits and 1,000 volts for AC (alternating current) circuits.

How does high voltage direct current work?

How does HVDC Transmission System Work? In generating substation, AC power is generated, which is converted into DC using a rectifier. The DC flows through the overhead line, and then again at the user end, DC is converted into AC using inverters and then AC is supplied to the load.

Why is DC high voltage efficient?

HVDC is more efficient to transmit over long distances The reason why high-voltage DC has less energy losses over transmission lines is because high-voltage AC has much more "capacitive" losses than DC power, especially when conductors are closer to the ground.

Why AC is used instead of DC?

AC is much easier (therefore cheaper) to step up and down in voltage(using a transformer) than DC, and can be done more efficiently than the much more expensive and complex DC step-up/step-down systems. That is why AC is used for power transmission.

What is meant by high voltage?

A high voltage system carries more than 1000 Volts between conductors and 600 Volts between conductors and ground. By using transformers, the voltage of the power can be stepped up to a high voltage so that the power may be distributed over long distances at low currents and hence low losses.

Is high voltage AC?

The International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) define high voltage as above 1000 V for alternating current, and at least 1500 V for direct current.

Is HVDC better than AC?

High voltage direct current (HVDC) transmission lines are more efficient for transferring power over long distances, as they incur less power loss when compared with their equivalent high voltage alternating current (HVAC) transmission systems.

Can you get shocked by DC current?

Safety Aspects of AC and DC The human body has a higher impedance to DC currents than AC, so this means that humans are able to withstand the effects of an electric shock arising from DC exposure much better than when exposed to AC.

Can 24v DC shock you?

Conversely, 24VDC's main advantage over other voltage levels is safety. No arc flash hazards are present and the voltage is low enough that the shock hazard is almost negligible.

Why is DC current not used in homes?

Direct current can not be easily stepped up or stepped down with the help of transformers whereas alternating current can easily be converted from low voltage to high voltage or vice-versa with the help of transformers. The possibility of electrolytic corrosion is more in DC than in AC.

What are the advantages of HVDC?

HVDC systems are used in areas where power is transmitted over very long distances or to take power from offshore wind farms. The main advantage of HVDC is that it solves the problem of reactive power consumption for line charging, which occurs particularly on cable lines HVAC.

How far can DC voltage travel?

	24 AWG	16 AWG
DC 100mA	216 feet	1,379 feet
DC 200mA	108 feet	689 feet
DC 300mA	72 feet	459 feet
DC 400mA	54 feet	344 feet

How is HVDC produced?

In the HVDC station, the converter transformer steps-up the generated AC voltages to the required level. The converter station takes the electric power from the three-phase AC network and rectifies it to DC, which is then transmitted through overhead lines (or cables).

What are the disadvantages of DC?

Disadvantages of DC Transmission DC voltage cannot be directly step-up or step-down for transmitting the power at high voltages and for distributing it at low voltages. It requires extra equipment such rectifier and inverter, etc. which increases the cost of transmission.

Why can't DC travel long distances?

Since there was no way to increase the voltage of DC electricity before transmission, DC electricity couldn't travel very far without major losses, making DC systems inferior to AC systems.

Why do cars use DC current?

When batteries discharge they emit a constant DC power in one direction, supplying electricity through the positive terminal to the negative. Most automotive components require this DC charge to work properly, but it is limited because batteries will eventually discharge completely, with no remaining power to give.

Why is DC better for long distances?

“If the transmission line route is longer than about 300 miles, DC is a better option because AC lines have more line losses than DC for bulk power transfer.”

Can you run a house on DC power?

All residential loads can run on DC power, but only some of them absolutely must use DC electricity today. These native DC loads include effectively all electronic devices, embedded electronics in large devices such as appliances, and LED and CFL lighting.