Efficiency (Efficiency, PSU Efficiency - eng.) - a parameter that indicates how efficiently the power supply can convert energy for the needs of components. It is measured as a percentage and the more it tends to 100%, the higher the efficiency.

What is power supply efficiency .

The power supply is a switching converter that pre-converts AC to DC. Alternating current is filtered, passes through filters, and other converters. With this transformation, part of the energy is lost with electromagnetic harmonics, the resistance of the elements and, accordingly, with heat. If we compare the input power and the output power, the output will always be less. Ratio incoming and outgoing energy is efficiency.

By the level of efficiency, one can judge about quality element base in the power supply, since to achieve high values, more expensive and high-quality components are used. Manufacturers BP, new technologies are applied to increase the level efficiency. For example, quadruple and double transformers, electronic current and protection control systems, in the end, high-quality soldering for less resistance.

Pros from high level efficiency .

1. High efficiency saves electricity, which can better affect your electricity bills. In a single case, the savings are not big, but in the long run you will get good savings. In addition, if your computer consumes a significant amount of energy, the benefit of a high efficiency will be higher.

In organizations where computers 50 and more, high efficiency will save a significant amount of money for electricity and help save on electrical equipment of the supply network, due to the lower required power.

2. High efficiency, as a result, reduces the heating of the components inside the power supply, due to lower current losses and, as a result, less conversion of electricity into thermal energy. This reduces the frequency of the fan and reduce noise. But the main thing is that under more favorable operating conditions, most of the components of the power supply serve much longer. In particular, this applies to power circuits and, which are not tolerant of constant overheating.

3. Higher quality components in the power supply with high efficiency. For increase efficiency, high-quality components and reliable soldering are used. This also increases the life of the power supply and all its characteristics: the level of ripple, maintaining the desired voltage, the possibility of energy transfer, the influence of power lines on each other.

Standard 80 Plus.What it is?

Power supplies that received 80PLUS certificate, must give an efficiency not lower than a certain level under load from 20 to 100%. Certificates differ in percentage and title, from worst to best − Plus,Bronze, Silver, Gold, Platinum and recently introduced Titanium.

Notably, the certification has different percentages for different voltages. Different percentages apply when working from 115 (America) and 230 volt (Europe).

The presence of any of these certificates indicates a fairly high-quality element base and the higher the standard, the higher the quality of the power supply. For home use, it is enough to have a power supply with a standard Bronze or Silver. Further, the percentage increase efficiency grows much more slowly than prices for such BP.

When using LEDs as the main light source, the question arises - how much power of fixtures is needed for this. To answer it, you need to know what determines the efficiency of LEDs.

LED element efficiency

In an ideal LED with an efficiency of 100%, each incoming electron emits a photon of light. Such efficiency is unattainable. In real devices, it is estimated by the ratio of the luminous flux to the supplied (consumed) power.

This indicator is influenced by several factors:

• Radiation efficiency. This is the number of photons emitted at the p-n junction. The voltage drop across it is 1.5-3V. With a further increase in the supply voltage, it does not grow, but the current through the device and the brightness of the light increase. Unlike an incandescent lamp, it has a linear dependence on the current flowing only up to a certain value. With a further increase in current, additional electrical power is consumed only for heating, which leads to a drop in efficiency.
• optical output. All selected photons should be emitted into the surrounding space. This is the main limiting factor for increasing the efficiency of LEDs.
• Some LEDs are coated with a phosphor layer for better color reproduction. In this case, the efficiency of the device is additionally affected by light conversion efficiency.

At the beginning of the 21st century, an efficiency of 4% was considered the norm, and now a record of 60% has been set, which is 10 times more than that of an incandescent lamp.

The "hospital average" efficiency for top manufacturers like Philips or Cree ranges from 35-45%. The exact parameters can be seen in the datasheet of a specific model. Efficiency for budget Chinese LEDs is always a roulette with a spread of 10-45%.

But these are theoretical indicators that we cannot influence. In practice, the current supplied to the diode and the temperature regime play a key role. An excellent job was done by a YouTube user under the nickname berimor76, showing in practice the dependence of the luminous flux on the supplied current and temperature. Let's watch the video.

Power supply efficiency

In addition to the efficiency of the LEDs themselves, the energy efficiency of LED lamps and fixtures is affected by the power source. They are of two types:

• Power Supply. Provides a constant, predetermined voltage to the LEDs, regardless of the current drawn.
• Driver. Provides a constant current value. The voltage does not matter.

Power Supply

The power supply supplies the LED with a voltage higher than necessary for p-n openings transition. But the resistance of an open diode is very small. Therefore, a resistor is installed in series with the light source to limit the current. The power released on it is completely converted into heat, which reduces efficiency. LED lamp. For example, in the led-tape, the losses are about 25%.

A more advanced and economical device is an electronic driver.

Driver

The driver for powering the LEDs provides them with a constant current. Diodes are connected to the device in series in a number that depends on the operating voltage of the LEDs and the maximum voltage of the device.

LED lamps use a current-limiting capacitor instead of a driver. When an electric current passes through it, the so-called reactive power is released. It does not turn into heat, but the electric meter still takes it into account. The efficiency of such a "driver" depends on the number of diodes connected in series with it.

The electronic driver is installed in high power luminaires or in portable devices where saving electricity or battery capacity is more important than the price of the device.

Luminaire efficiency

When organizing lighting, including LED, the efficiency of the form factor of the lamp matters. This is the ratio of all the light coming out of the lamp to luminous flux emitted by the lamp itself.

Any design of the lamp, even made of mirrors or transparent glass, absorbs light. The ideal lossless option is a bulb holder suspended from wires.

But this is a rare case when perfect does not mean best. The luminous flux from the light bulb on the wire is directed in all directions, and not just in the right direction. Of course, the light that hits the ceiling or walls is reflected from them, but not all, especially in the open air or in a room with dark wallpaper.

The same disadvantage has LED lamp with a versatile arrangement of elements ("corn") or with a matte dispersion. In the latter case, the diffuser additionally absorbs light.

Unlike such lamps, a one-sided LED lamp directs light in one direction. The efficiency of a lamp with such a lamp is close to 100%. The illumination created by it is higher than that of the other, with the same luminous flux, but directed in different sides.

It's connected with design features LEDs - unlike incandescent and fluorescent (energy-saving) lamps with a circular orientation of radiation, they emit light in the range of 90-120 degrees. The same properties are possessed by LED strips and spotlights that emit light in only one direction.

Thus, the maximum luminous flux per watt of power is emitted by LEDs in spotlights with an integrated electronic driver.

The power supply provides power to all PC components. We will explain how this device works.

Although the computer plugs into a standard electrical outlet, its components cannot draw power directly from the power outlet for two reasons.

First, the network uses alternating current, while computer components require direct current. Therefore, one of the tasks of the power supply is to "rectify" the current.

Secondly, different computer components require different supply voltages for operation, and some require several lines with different voltages at once. The power supply provides each device with current with the necessary parameters. To do this, it provides several power lines. For example, the power connectors of hard drives and optical drives are supplied with 5 V for electronics and 12 V for the motor.

Power supply specifications

The power supply is the only source of electricity for all PC components, therefore, the stability of the entire system directly depends on the characteristics of the current it produces. The main characteristic of the PSU is power. It should be at least equal to the total power consumed by PC components at maximum computing load, and even better if it exceeds this figure by 100 W or more. Otherwise, the computer will turn off at times of peak load or, much worse, the PSU will burn out, taking other system components with it.

For most office computers, 300W is sufficient. The power supply of the gaming machine must have a power of at least 400 W - high-performance processors and fast video cards, as well as the additional cooling systems they need, consume a lot of energy. If the computer has several video cards, then 500- and 650-watt PSUs will be required to power it. There are already models with a power of more than 1000 W on sale, but buying them is almost pointless.

Often, PSU manufacturers shamelessly overestimate the nominal power value, most often buyers of cheap models face this. We advise you to choose the power supply based on the test data. In addition, the power of the PSU is easiest to determine by weight: the larger it is, the higher the likelihood that the real power of the power supply corresponds to the declared one.

In addition to the total power of the power supply, its other characteristics also matter:

Maximum current on individual lines. The total power of the PSU is the sum of the powers that it can provide on individual power lines. If the load on one of them exceeds the allowable limit, the system will lose stability even if the total power consumption is far from the power supply rating. The load on the lines in modern systems, as a rule, is uneven. The 12-volt channel is the heaviest of all, especially in configurations with powerful video cards.

Dimensions. When specifying the dimensions of the PSU, manufacturers, as a rule, limit themselves to the designation of the form factor (modern ATX, outdated AT or exotic BTX). But manufacturers of computer cases and power supplies do not always strictly adhere to the norm. Therefore, when buying a new power supply, we advise you to compare its dimensions with the dimensions of the “seat” in your PC case.

Connectors and cable lengths. The power supply must have at least six Molex connectors. A computer with two hard drives and a pair of optical drives (for example, a DVD-RW writer and a DVD reader) already has four such connectors, and other devices can be connected to the Molex, such as case fans and video cards with an AGP interface.

The power cables must be long enough to reach all the required connectors. Some manufacturers offer power supplies, the cables of which are not soldered to the board, but are connected to the connectors on the case. This reduces the number of wires dangling in the case, and therefore reduces the mess in the system unit and contributes to better ventilation of its insides, as it does not interfere with the air flow circulating inside the computer.

Noise. During operation, the components of the power supply become very hot and require enhanced cooling. For this, fans built into the PSU case and heatsinks are used. Most power supplies use a single 80mm or 120mm fan, and the fans are quite noisy. Moreover, the higher the power of the PSU, the more intense air flow is required in order to cool it. To reduce the noise level in high-quality power supplies, fan speed control circuits are used in accordance with the temperature inside the PSU.

Some power supplies allow the user to determine the fan speed using the regulator on the back of the PSU.

There are PSU models that continue to ventilate system unit some time after turning off the computer. Thanks to this, PC components cool down faster after work.

The presence of a tumbler. The switch on the back of the power supply allows you to completely de-energize the system if it becomes necessary to open the computer case, so its presence is welcome.

Additional characteristics of the power supply

The high power of the power supply in itself does not guarantee high-quality work. In addition to it, other electrical parameters also matter.

Efficiency factor (COP). This indicator indicates what proportion of the energy consumed by the power supply from the electrical network goes to the computer components. The lower the efficiency, the more energy is wasted on useless heat generation. For example, if the efficiency is 60%, then 40% of the energy from the outlet is lost. This increases power consumption and leads to a strong heating of the PSU components, and consequently - to the need for enhanced cooling with a noisy fan.

Good power supplies have an efficiency of 80% or more. They can be recognized by the "80 Plus" sign. Recently, three new more stringent standards have been in effect: 80 Plus Bronze (efficiency of at least 82%), 80 Plus Silver (from 85%) and 80 Plus Gold (from 88%).

The PFC (Power Factor Correction) module allows you to significantly increase the efficiency of the power supply. It is of two types: passive and active. The latter is much more efficient and allows you to achieve an efficiency level of up to 98%, for a PSU with passive PFC, an efficiency of 75% is typical.

Voltage stability. The voltage on the power supply lines fluctuates depending on the load, but it should not go beyond certain limits. Otherwise, system malfunctions or even failure of its individual components are possible. Hoping for voltage stability allows, first of all, the power of the power supply.

Safety. High-quality power supplies are equipped with various systems to protect against power surges, overload, overheating and short circuits. These features protect not only the power supply, but also other computer components. Note that the presence of such systems in the power supply does not exclude the need to use uninterruptible power supplies and network filters.

The main characteristics of the power supply

Each power supply has a sticker indicating its specifications. The main parameter is the so-called Combined Power or Combined Wattage. This is the maximum total power for all existing power lines. In addition, the maximum power for individual lines also matters. If there is not enough power on some line to “feed” the devices connected to it, then these components may work unstably, even if the total power of the PSU is enough. As a rule, not all power supplies indicate the maximum power for individual lines, but all of them indicate the current strength. Using this parameter, it is easy to calculate the power: for this, you need to multiply the current by the voltage in the corresponding line.

12 V. 12 volts is supplied, first of all, to powerful consumers of electricity - a video card and a central processor. The power supply must provide as much power as possible on this line. For example, a 12-volt power supply line is designed for a current of 20 A. At a voltage of 12 V, this corresponds to a power of 240 watts. High performance graphics cards can deliver up to 200W or more. Power is supplied to them through two 12-volt lines.

5 V. 5 V lines supply power motherboard, hard drives and optical drives PC.

3.3 V. The 3.3 V lines go only to the motherboard and provide power to the RAM.

Content:

In the process of moving charges within a closed circuit, a certain work is performed by the current source. It can be useful and complete. In the first case, the current source moves charges in the external circuit, while doing work, and in the second case, the charges move in the entire circuit. In this process, the efficiency of the current source, defined as the ratio of the external and total resistance of the circuit, is of great importance. If the internal resistance of the source and the external resistance of the load are equal, half of all power will be lost in the source itself, and the other half will be released at the load. In this case, the efficiency will be 0.5 or 50%.

Electric circuit efficiency

The considered efficiency is primarily associated with physical quantities characterizing the rate of conversion or transmission of electricity. Among them, in the first place is the power, measured in watts. There are several formulas for its definition: P = U x I = U2/R = I2 x R.

In electrical circuits, there can be a different voltage value and charge value, respectively, and the work performed is also different in each case. Very often there is a need to estimate the speed with which electricity is transmitted or converted. This speed is the electrical power corresponding to the work performed in a certain unit of time. In the form of a formula, this parameter will look like this: P=A/∆t. Therefore, the work is displayed as the product of power and time: A=P∙∆t. The unit of measure for work is .

In order to determine how efficient a device, machine, electrical circuit or other similar system is, in terms of power and work, efficiency is used - efficiency. This value is defined as the ratio of useful energy spent to the total amount of energy supplied to the system. The efficiency is denoted by the symbol η, and mathematically defined as the formula: η \u003d A / Q x 100% \u003d [J] / [J] x 100% \u003d [%], in which A is the work done by the consumer, Q is the energy given by the source . In accordance with the law of conservation of energy, the efficiency value is always equal to or below unity. This means that useful work cannot exceed the amount of energy spent on its completion.

Thus, the power losses in any system or device are determined, as well as the degree of their usefulness. For example, in conductors, power losses are formed when electricity partially converted into thermal energy. The amount of these losses depends on the resistance of the conductor, they are not an integral part of the useful work.

There is a difference, expressed by the formula ∆Q=A-Q, which clearly shows the power loss. Here, the relationship between the growth of power losses and the resistance of the conductor is very clearly visible. The most striking example is an incandescent lamp, the efficiency of which does not exceed 15%. The remaining 85% of the power is converted into thermal, that is, into infrared radiation.

What is the efficiency of the current source

The considered efficiency of the entire electrical circuit makes it possible to better understand the physical essence of the efficiency of the current source, the formula of which also consists of various quantities.

In the process of moving electric charges along a closed electrical circuit, a certain work is performed by the current source, which differs as useful and complete. During the performance of useful work, the current source moves charges in the external circuit. At full work, the charges, under the influence of a current source, move already throughout the circuit.

In the form of formulas, they are displayed as follows:

• Useful work - Apolesis = qU = IUt = I2Rt.
• Complete work - Afull = qε = Iεt = I2(R +r)t.

Based on this, it is possible to derive formulas for the useful and total power of the current source:

• Useful power - Рpolez = Apolez / t = IU = I2R.
• Apparent power - Рfull = Apfull/t = Iε = I2(R + r).

As a result, the formula for the efficiency of the current source takes the following form:

• η = Ause/ Atot = Ruse/ Ptot = U/ε = R/(R + r).

The maximum useful power is achieved at a certain value of the resistance of the external circuit, depending on the characteristics of the current source and load. However, attention should be paid to the incompatibility between maximum net power and maximum efficiency.

Investigation of the power and efficiency of the current source

The efficiency of a current source depends on many factors, which should be considered in a certain sequence.

To determine, in accordance with Ohm's law, there is the following equation: i \u003d E / (R + r), in which E is the electromotive force of the current source, and r is its internal resistance. These are constant values ​​​​that do not depend on the variable resistance R. With their help, you can determine the useful power consumed by the electrical circuit:

• W1 \u003d i x U \u003d i2 x R. Here R is the resistance of the consumer of electricity, i is the current in the circuit, determined by the previous equation.

Thus, the power value using finite variables will be displayed as follows: W1 = (E2 x R)/(R + r).

Since it is an intermediate variable, in this case the function W1(R) can be analyzed for an extremum. To this end, it is necessary to determine the value of R, at which the value of the first derivative of the useful power associated with the variable resistance (R) will be equal to zero: dW1/dR = E2 x [(R + r)2 - 2 x R x (R + r) ] = E2 x (Ri + r) x (R + r - 2 x R) = E2(r - R) = 0 (R + r)4 (R + r)4 (R + r)3

From this formula, we can conclude that the value of the derivative can be zero only under one condition: the resistance of the power receiver (R) from the current source must reach the value of the internal resistance of the source itself (R => r). Under these conditions, the value of the efficiency factor η will be determined as the ratio of the useful and total power of the current source - W1/W2. Since at the maximum point of useful power the resistance of the energy consumer of the current source will be the same as the internal resistance of the current source itself, in this case the efficiency will be 0.5 or 50%.

Tasks for current power and efficiency

Hello dear friends. Artyom is with you as always.

Today we will talk about efficiency ( efficiency) computer power supply and why you don't need a super powerful power supply.

What is power supply efficiency? In simple and understandable terms, this is the ratio of the energy consumed (power in Watts) from the outlet to the energy given off by the computer components.

Part of the energy is spent on the operation of the power supply circuit, as well as on the heating of components during its operation.

The higher the efficiency of the power supply (closer to 100%), the less it consumes from the outlet, since less energy is lost to heat its components during operation.

Video version of the article:

Let's look at a simple and very illustrative example.

There is a power supply with a rated power of 600 watts, and its efficiency is 70%.

How much will it consume from the outlet at maximum load?

600 watts x 100%/70% = 857 watts.

That is, such a power supply at maximum load will give 600 watts to computer components, but in fact it will consume as much as 257 watts more from the outlet!

With higher efficiency and the same power supply capacity, the actual consumption from the socket will decrease (as will the electricity bill).

60-75 percent is a typical efficiency for a computer power supply.

However, in 2007, the 80 Plus certification appeared, which significantly increased the level of efficiency of power supplies. Initially, there were no additional prefixes, Silver, Gold, and so on.

They appeared later, increasing the efficiency of the power supply by several percent each.

80 Plus certification was only for a supply voltage of 115 volts. Later, all subsequent certifications got rid of this drawback and were already tested at a supply voltage of 230 volts.

In the screenshot you see all the indicators for each 80 Plus certification.

As you can see, the maximum efficiency is achieved at a load level of 50% and drops at 100% load.

Now let's calculate the actual consumption from the outlet, a 600-watt power supply, with a 50% load from computer components.

705 Watt 80 Plus Silver

674 Watts 80 Plus Bronze

652 Watts 80 Plus Gold

638 Watt 80 Plus Platinum

625 Watt 80 Plus Titanium

P.S. Power supplies with the last two standards are quite expensive.

As a rule, it does not make much sense to overpay here. This is of course my personal opinion. Although for power over 1000 watts, these standards will be quite relevant.

On a special website, you can see which specific models of power supplies have been certified according to 80 Plus standards:

Let's calculate how many more extra watts the power supply will consume in a year, with different certifications.

– 306 kilowatts. The computer works 8 hours a day, up to 50% load on the power supply, 365 days. 80 Plus Silver Certified, 600W PSU Power.

(705 watts total consumption. 705 watts - 600 watts (rated power output) = 105 watts. 105 watts x 8 hours x 365 days = 306.600 watts = 306 kilowatts).

– 151 kilowatts. The computer works 8 hours a day, up to 50% load on the power supply, 365 days. 80 Plus Gold Certified, 600W PSU.

(705 watts total consumption. 652 watts - 600 watts (rated power output) = 52 watts. 52 watts x 8 hours x 365 days = 151.840 watts = 151 kilowatts).

151 kilowatts / 365 days = 25.5 kilowatts per month 80 Plus Silver.

306 kilowatts / 365 days = 12.5 kilowatts per month 80 Plus Gold.

Thus, with an 80 Plus Gold power supply, you can actually cut the amount of extra watts consumed by half.

It happens that people buy super powerful power supplies for their systems. Of course, you need to have a margin of 30 percent, but everything should be within reasonable limits.

Your system, at maximum load (when you play, render video, and so on), should load the power supply by at least 50%, only in this case the power supply can reach the maximum level of efficiency and, accordingly, save energy.

Therefore, you do not need to buy some kind of Kilowatt for a system of GTX 1080 and Core i7 7700K. Not only do you simply overpay for unnecessary excess power, but also for the increase in actual power consumption from the outlet.

Of course, the power supply should not have too little power for the system under load, but this is not discussed.

P.S. You can see how much your system will consume approximately on the websites of power supply power calculators.

I hope that it has become clear to you what the efficiency of a computer power supply is and what it ultimately affects.

! Write in the comments which power supply you have installed (power and certification, if any) and which system it powers. I will be interested to read.

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