- 相關(guān)推薦
有功功率和無(wú)功功率
有功功率/無(wú)功功率Active power/reactive power 在交流電路中，由電源供給負(fù)載的電功率有兩種；一種是有功功率，一種是無(wú)功功率。
有功功率是保持用電設(shè)備正常運(yùn)行所需的電功率，也就是將電能轉(zhuǎn)換為其他形式能量(機(jī)械能、光能、熱能)的電功率。比如：5.5千瓦的電動(dòng)機(jī)就是把5.5千瓦的電能轉(zhuǎn)換為機(jī)械能，帶動(dòng)水泵抽水或脫粒機(jī)脫粒；各種照明設(shè)備將電能轉(zhuǎn)換為光能，供人們生活和工作照明。有功功率的符號(hào)用P表示，單位有瓦(W)、千瓦(kW)、兆瓦(MW)。
無(wú)功功率比較抽象，它是用于電路內(nèi)電場(chǎng)與磁場(chǎng)的交換，并用來(lái)在電氣設(shè)備中建立和維持磁場(chǎng)的電功率。它不對(duì)外作功，而是轉(zhuǎn)變?yōu)槠渌问降哪芰�。凡是有電磁線圈的電氣設(shè)備，要建立磁場(chǎng)，就要消耗無(wú)功功率。比如40瓦的日光燈，除需40多瓦有功功率(鎮(zhèn)流器也需消耗一部分有功功率)來(lái)發(fā)光外，還需80乏左右的無(wú)功功率供鎮(zhèn)流器的線圈建立交變磁場(chǎng)用。由于它不對(duì)外做功，才被稱之為“無(wú)功”。無(wú)功功率的符號(hào)用Q表示，單位為乏(Var)或千乏(kVar)。
無(wú)功功率決不是無(wú)用功率，它的用處很大。電動(dòng)機(jī)需要建立和維持旋轉(zhuǎn)磁場(chǎng)，使轉(zhuǎn)子轉(zhuǎn)動(dòng)，從而帶動(dòng)機(jī)械運(yùn)動(dòng)，電動(dòng)機(jī)的轉(zhuǎn)子磁場(chǎng)就是靠從電源取得無(wú)功功率建立的。變壓器也同樣需要無(wú)功功率，才能使變壓器的一次線圈產(chǎn)生磁場(chǎng)，在二次線圈感應(yīng)出電壓。因此，沒(méi)有無(wú)功功率，電動(dòng)機(jī)就不會(huì)轉(zhuǎn)動(dòng)，變壓器也不能變壓，交流接觸器不會(huì)吸合。為了形象地說(shuō)明這個(gè)問(wèn)題，現(xiàn)舉一個(gè)例子：農(nóng)村修水利需要開挖土方運(yùn)土，運(yùn)土?xí)r用竹筐裝滿土，挑走的土好比是有功功率，挑空竹筐就好比是無(wú)功功率，竹筐并不是沒(méi)用，沒(méi)有竹筐泥土怎么運(yùn)到堤上呢?
在正常情況下，用電設(shè)備不但要從電源取得有功功率，同時(shí)還需要從電源取得無(wú)功功率。如果電網(wǎng)中的無(wú)功功率供不應(yīng)求，用電設(shè)備就沒(méi)有足夠的無(wú)功功率來(lái)建立正常的電磁場(chǎng)，那么，這些用電設(shè)備就不能維持在額定情況下工作，用電設(shè)備的端電壓就要下降，從而影響用電設(shè)備的正常運(yùn)行。 無(wú)功功率對(duì)供、用電產(chǎn)生一定的不良影響，主要表現(xiàn)在：
(1)降低發(fā)電機(jī)有功功率的輸出。
(2)降低輸、變電設(shè)備的供電能力。
(3)造成線路電壓損失增大和電能損耗的增加。
(4)造成低功率因數(shù)運(yùn)行和電壓下降，使電氣設(shè)備容量得不到充分發(fā)揮。
從發(fā)電機(jī)和高壓輸電線供給的無(wú)功功率，遠(yuǎn)遠(yuǎn)滿足不了負(fù)荷的需要，所以在電網(wǎng)中要設(shè)置一些無(wú)功補(bǔ)償裝置來(lái)補(bǔ)充無(wú)功功率，以保證用戶對(duì)無(wú)功功率的需要，這樣用電設(shè)備才能在額定電壓下工作。這就是電網(wǎng)需要裝設(shè)無(wú)功補(bǔ)償裝置的道理。
電壓電流同相位，電源向負(fù)載供電，負(fù)載把電能轉(zhuǎn)換成其他能量，叫有功。
電壓電流不同相位部分，電源與負(fù)載之間交換電能，這部分（除線路損耗外）電能不轉(zhuǎn)換（電磁以外的）成其他能量，叫無(wú)功。 有功功率
有功功率是保持用電設(shè)備正常運(yùn)行所需的電功率，也就是將電能轉(zhuǎn)換為其他形式能量(機(jī)械能、光能、熱能)的電功率。比如：5.5千瓦的電動(dòng)機(jī)就是把5.5千瓦的電能轉(zhuǎn)換為機(jī)械能，帶動(dòng)水泵抽水或脫粒機(jī)脫粒；各種照明設(shè)備將電能轉(zhuǎn)換為光能，供人們生活和工作照明。有功功率的符號(hào)用P表示，單位有瓦(W)、千瓦(kW)、兆瓦(MW)。定義：有功功率:在交流電路中，電源在一個(gè)周期內(nèi)發(fā)出瞬時(shí)功率的平均值(或負(fù)載電阻所消耗的功率)，稱為"有功功率"。
有功功率過(guò)低導(dǎo)致線損增加、容量下降、設(shè)備使用率下降，從而導(dǎo)致電能浪費(fèi)加大。
無(wú)功功率
電網(wǎng)中的感性負(fù)載（如電機(jī)，扼流圈，變壓器，感應(yīng)式加熱器及電焊機(jī)等）都會(huì)產(chǎn)生不同程度的電滯，即所謂的電感。
感性負(fù)載具有這樣一種特性 -----即使所加電壓改變方向，感性負(fù)載的這種滯后仍能將電流的方向（如正向）保持一段時(shí)間。一旦存在了這種電流與電壓之間的相位差，就會(huì)產(chǎn)生負(fù)功率，并被反饋到電網(wǎng)中。電流電壓再次相位相同時(shí)，又需要相同大小的電能在感性負(fù)載中建立磁場(chǎng)，這種磁場(chǎng)反向電能就被稱作無(wú)功功率。
定義：在具有電感或電容的電路中，在每半個(gè)周期內(nèi)，把電源能量變成磁場(chǎng)(或電場(chǎng))能量貯存起來(lái)，然后，再釋放，又把貯存的磁場(chǎng)（或電場(chǎng)）能量再返回給電源，只是進(jìn)行這種能量的交換，并沒(méi)有真正消耗能量，我們把這個(gè)交換的功率值，稱為" 無(wú)功功率"。
無(wú)功功率比較抽象，它是用于電路內(nèi)電場(chǎng)與磁場(chǎng)的交換，并用來(lái)在電氣設(shè)備中建立和維持磁場(chǎng)的電功率。它不對(duì)外作功，而是轉(zhuǎn)變?yōu)槠渌?/p>
形式的能量。凡是有電磁線圈的電氣設(shè)備，要建立磁場(chǎng)，就要消耗無(wú)功功率。比如40瓦的日光燈，除需40多瓦有功功率(鎮(zhèn)流器也需消耗一部分有功功率)來(lái)發(fā)光外，還需80乏左右的無(wú)功功率供鎮(zhèn)流器的線圈建立交變磁場(chǎng)用。由于它不對(duì)外做功，才被稱之為“無(wú)功”。無(wú)功功率的符號(hào)用Q表示，單位為乏(Var)或千乏(kVar)。
無(wú)功功率過(guò)高的缺點(diǎn) ：
1）無(wú)功功率會(huì)導(dǎo)致電流增大和視在功率增加，導(dǎo)致系統(tǒng)容量下降；
2）無(wú)功功率增加，會(huì)使總電流增加，從而使設(shè)備和線路的損耗增加；
3）使線路的壓降增大，沖擊性無(wú)功負(fù)載還會(huì)使電壓劇烈波動(dòng)。
配電網(wǎng)中的電感性電氣設(shè)備如變壓器、電動(dòng)機(jī)、電焊機(jī)、空調(diào)器、洗衣機(jī)、電冰箱、鈉燈、日光燈等投入運(yùn)行后，不僅要從電力網(wǎng)中吸收有功功率用于做功，而且還要吸收無(wú)功功率建立磁場(chǎng)，這樣就導(dǎo)致電力客戶的自然功率因數(shù)一般都比較低。我國(guó)對(duì)電力客戶的用電，規(guī)定了必須達(dá)到的功率因數(shù)標(biāo)準(zhǔn)。
有功可以直接測(cè)量；有功與無(wú)功混在一起，無(wú)法直接區(qū)分開來(lái)，可以通過(guò)功率因數(shù)表測(cè)量。
In the circuit, the power supply by the two kinds of power load; One is the active power, one kind is reactive power.
Active power is to maintain the normal operation of the power equipment needed to power, is also to electric energy into other forms of energy (mechanical energy, light and heat energy) of power. For example: 5.5 kw motor is that of the 5.5 kw electrical energy into mechanical energy, drive the pumps pumping or the threshers threshing; Lighting equipment will be electric energy into light energy conversion, for people living and working lighting. The symbol of the active power with P says, the unit has watts (W), kilowatts (kW), megawatts (MW). Reactive power are abstract, it was used in the circuit of electric and magnetic field exchange, and used in electrical equipment to establish and maintain the magnetic field of power. It is not foreign energy, but changed into other forms of energy. Anyone with a magnetic coil of electrical equipment, to build a magnetic field, are about to use up reactive power. Such as 40 watts of fluorescent lamp, in addition to more than 40 tile active power (ballast also need to consume part of active power) to shine outside, still need to be around 80 lack of reactive power for ballast coil set up with alternating magnetic field. Because it is not foreign work, to be called "reactive power". Reactive power symbol using qq said, the unit is deficient (Var) or lack of thousands (kVar).
Reactive power is not useless power, it's very useful. Motor need to establish and maintain a rotating magnetic field, make the rotor, thus promote mechanical motion, motor rotor magnetic field is obtained from power by reactive power built. Transformer also require the reactive power, can cause the transformer a coil produce a magnetic field, at two times the voltage induction coil. Therefore, no reactive power, the motor does not turn, transformer cannot variable pressure, ac contactor won't suck $. In order to the image of the illustration of this problem, we give an example: rural water need to repair carried earth excavation earthwork, carried earth with ZhuKuang when filled with earth, the earth is like pick is active power, ZhuKuang carry empty is like a reactive power, ZhuKuang and not a useless, no ZhuKuang clay to DiShang how?
In normal circumstances, electrical equipment from power not only to get active power, which needs to be obtained from the power supply reactive power. If in the grid reactive power demand exceeds supply, power equipment is not enough reactive power to establish normal
electromagnetic fields, so, the electric equipment cannot be maintained in the rated work, electrical equipment will decline voltage, which affects the normal operation of the power equipment. Reactive power for electricity to produce a certain, bad influence, mainly displays in: (1) reduce the output of the active power generator.
(2) reduce the loss of power supply, the substation equipment.
(3) cause line voltage loss increase and the increase of the electric power. (4) cause low power factor operation and voltage fell, the electrical equipment capacity can not make full play. From the generator and the high voltage transmission line of reactive power supply, far meet the needs of the load, so in the power grid to set some of the reactive power compensation device to supplement the reactive power, in order to ensure that the user to the reactive power needed, so that power equipment can work under rated voltage. This is the power grid needs reactive power compensation devices of reason. Voltage current with phase, the power to load power supply, the load the energy conversion to other energy, called active.
Voltage current different phase part, source and load exchange between power, this part
(except the line loss outside) power not to convert (electromagnetic outside of the) into other energy, called reactive. Active power
Active power is to maintain the normal operation of the power equipment needed to power, is also to electric energy into other forms of energy (mechanical energy, light and heat energy) of power. For example: 5.5 kw motor is that of the 5.5 kw electrical energy into mechanical energy, drive the pumps pumping or the threshers threshing; Lighting equipment will be
electric energy into light energy conversion, for people living and working lighting. The symbol of the active power with P says, the unit has watts (W), kilowatts (kW), megawatts (MW). Definition: active power: in the circuit, the power supply in a cycle of inside an instantaneous power average (or load resistance of power consumption), known as the "active power". Active power is too low to increase capacity drops, and line loss, equipment utilization rate is reduced, which can lead to increased power waste.
Reactive power In the grid perceptual load (such as motor, choke, transformer, induction heater and electric) produce different degree of electricity sluggish, the so-called inductance. The perceptual load has such a characteristics-even if the voltage change of direction,
perceptual load this lag still current direction (such as positive) keep a period of time. Once existed for this current and voltage of the phase difference between, can produce negative power, and in the power to be feedback. Again the same in current voltage phase, and the need to same size of the electricity in the perceptual load established in magnetic field, the magnetic field reverse power is known as reactive power.
Definition: in a inductor or capacitance circuit, in each half a cycle, the power energy into the magnetic field (or electric field) energy stored, and then, then released, and the storage of the magnetic field (or electric field) energy returned to power again, just this energy exchange, and no real energy consumption, and we put the exchange value of power, called "reactive power". Reactive power are abstract, it was used in the circuit of electric and magnetic field exchange, and used in electrical equipment to establish and maintain the magnetic field of power. It is not foreign energy, but changed into other forms of energy. Anyone with a magnetic coil of
electrical equipment, to build a magnetic field, are about to use up reactive power. Such as 40 watts of fluorescent lamp, in addition to more than 40 tile active power (ballast also need to consume part of active power) to shine outside, still need to be around 80 lack of reactive power for ballast coil set up with alternating magnetic field. Because it is not foreign work, to be called "reactive power". Reactive power symbol using qq said, the unit is deficient (Var) or lack of thousands (kVar). Reactive power the shortcomings of high 1) reactive power will lead to current increases and installed power increase, cause the system capacity drops; 2) reactive power increase, can make the total current increase, which makes equipment and line loss increase; 3) make line pressure drop increases, impact reactive load will also make voltage sharp fluctuations.
The distribution network inductive electrical equipment such as transformer, electric motors,
electric welding machine, air conditioner, washing machines, refrigerators, sodium lamp, fluorescent lamp, and other inputs after the operation, not only to absorb the active power from the grid for work, but also to absorb reactive power establish magnetic field, this leads to electric power customer the natural power factor is compared commonly low. Our country to electric power customer the electricity, provisions must be met the power factor of standards. Active can be directly measured; Active and reactive mix together, not directly to distinguish, t 什么叫功率因數(shù)？
在電路由感性或讓性能源存儲(chǔ)設(shè)備,電壓和電流有相位差,流行講就是電壓和電流不相同的時(shí)間;
因此,表面看電壓、電流大小如何,實(shí)際的和沒(méi)有做那么大的工作,有權(quán)力和能源存儲(chǔ)設(shè)備的能源轉(zhuǎn)換;所謂的裝機(jī)功率。目前,電力有源+無(wú)功功率。
的意思是,無(wú)論有功功率和無(wú)功功率是多少,只能輸出電壓和電流太大。
是有功功率和無(wú)功功率適量,因?yàn)橛泄β屎蜔o(wú)功功率成90度角,用鐵鉤電力變壓器容量安裝power稱,單位是current-voltage(VA)。
功率因數(shù)計(jì)算公式。有功功率與視在功率之比
如果你家里的“感性負(fù)載的“更重要的是,如汽車、微波爐……用電器,比如更,吸收的反應(yīng)將會(huì)更多,和功率因數(shù)小,電力部門是小(無(wú)功功率不消費(fèi),只是從電網(wǎng)到你的家庭電器在吸收)
對(duì)于企業(yè),供電部門有監(jiān)管權(quán)力的數(shù)值,高于彩票,下面的懲罰。哈哈。
相當(dāng)復(fù)雜,其中涉及到安全的電力,電壓……當(dāng)然,包括變電站設(shè)備投資和投入運(yùn)行的可靠性、安全性和成本。而電力可以訪問(wèn)為測(cè)量。
What is called power factor?
In the circuit, the voltage and the phase
difference between the current (Φ) called the cosine power factor, with symbols cos Φ said, in numerical, power factor is active power and installed power
http://baike.baidu.com/view/56022.htm > ratio, namely cos Φ = P/S What is installed power?
In the circuit, with perceptual or let sexual energy storage equipment, the voltage and current with a phase difference, popular speak be voltage and current is not the same time;
Therefore, the surface see voltage is, how current size, actual and didn't do so big of work, there are power and energy storage equipment energy conversion; So called installed power. Already, the active power + reactive power.
Mean, whatever the active power and the reactive power is how much, can only output voltage and current so big.
Is the active power and the reactive power and right amount, because the active power and the reactive power into a 90 degree Angle, with hook power transformer installed with power said capacity, the unit is current-voltage (VA).
Stocks can calculate theorem. Active power/installed power = power factor,
If your home "perceptual load" is more, such as motor, microwave oven... With electric
equipment such as more, the absorption of reactive will more, and power factor is small, the electricity power department is little (reactive power is not consume, just from the power grid to your home electrical appliances in the absorption) Regarding the enterprise, power supply departments have the regulation of power for numerical values, higher than the lottery, below to the punishment. Ha ha. Quite complicated, which relates to safety of power, voltage... And, of course, involves the transformer substation equipment investment and put into operation reliability, safety and cost. hrough power can access for measurement. 什么叫視在功率？
在交流電路中，由于有感性或容性儲(chǔ)能設(shè)備，電壓與電流有相位差，通俗講就是電壓與電流不在同一時(shí)間到達(dá)；因此，表面看電壓有多大、電流有多大，實(shí)際并沒(méi)有做那么大的功，有電源與儲(chǔ)能設(shè)備的能量轉(zhuǎn)換； 所以稱為視在功率。既，有功功率+無(wú)功功率。
電力變壓器就用視在功率表示容量，單位為伏安(VA)。
意思是不管有功功率與無(wú)功功率是多少，只能輸出這么大的電壓與電流。 視在功率:在具有阻抗的交流電路中，電壓有效值與電流有效值的乘積值，稱為"視在功率"，它不是實(shí)際做功的平均值，也不是交換能量的最大速率，只是在電機(jī)或電氣設(shè)備設(shè)計(jì)計(jì)算較簡(jiǎn)便的方法。
關(guān)系:視在功率的平方=有功功率的平方+無(wú)功功率的平方
What is installed power?
In the circuit, with perceptual or let sexual energy storage equipment, the voltage and current
with a phase difference, popular speak be voltage and current is not the same time; Therefore, the surface see voltage is, how current size, actual and didn't do so big of work, there are power and energy storage equipment energy conversion;
So called installed power. Already, the active power + reactive power. Power transformer installed with power said capacity, the unit is current-voltage (VA).
Mean, whatever the active power and the reactive power is how much, can only output voltage and current so big. Installed power: in a circuit impedance, RMS voltage and current is the product of the RMS values, called "installed power", it is not the average of the actual work, also not the biggest energy exchange rate, just in the motor or electrical equipment design and calculation, a有功功率和無(wú)功功率 simple method. Relationships: installed power square = active power of square + reactive power square
如圖所示，電源電壓U=220V，頻率50Hz，求電流I，I1和I2，及電路有功，無(wú)功，視在功率，和功率因數(shù) Z1=10Ω Z2=5Ω，總電抗Z=10//5=10/3Ω
總電流I=U/Z=66A，I1=22A,I2=44A
有功功率P=I1?R1+I2?R2=2904+5808=8712W
視在功率S=UI=14520VA
無(wú)功功率Q=11616VAR
功率因數(shù)=P/S=0.6 有功功率、無(wú)功功率、視在功率三者之間的關(guān)系是怎樣的？計(jì)算公式是？
容量620KW,功率因數(shù)0.8,視在功率542KVA,無(wú)功功率應(yīng)該是多少?有公式嗎？
懸賞分：0 - 離問(wèn)題結(jié)束還有 5 天 22 小時(shí)
無(wú)功功率是怎樣算出來(lái)的?
提問(wèn)者： 2007xinwei2007 - 經(jīng)理 四級(jí)
視在功率＝（有功功率的平方＋無(wú)功功率的平方）開根號(hào)
有功功率＝視在功率×功率因數(shù)
在本計(jì)算中 P有功＝S視在×cosφ＝542×0.8=433.6KW
Q無(wú)功=√(542×542－433.6×433.6)＝325.2KVAR
或者根據(jù)cosφ求出sinφ 得出φ＝37 sinφ＝0.6
Q＝S× sinφ=542×0.6＝325.2KVAR
回答者：womyn5 - 千總 五級(jí) 7-3 17:59
這個(gè)有具體的數(shù)值，希望能夠更方便你理解
【有功功率和無(wú)功功率】相關(guān)文章：
初中物理《功和功率》優(yōu)秀教案05-18
今天沒(méi)有功課作文（精選22篇）08-07
測(cè)量小燈泡的電功率舊教案和新教案04-25
《功率》教案04-25
青蛙有功也有過(guò)-初一作文大全11-08
經(jīng)緯儀伺服功率級(jí)現(xiàn)狀和發(fā)展趨勢(shì)04-30
物理功率教案12-30
功率 典型例題05-01