About there also are many implied meanings on the discussion net of power factor, but a lot of people still are put to a few concepts have misunderstanding, this brings the design that is a system a lot of harm, be necessary to try to clarify again here.

 

One, the origin of power factor and meaning

 

There are 3 basic varieties in the load of electric field: Resistor, capacitance and inductance. Resistor is the parts of an apparatus that consumes power, capacitance and inductance are to store the parts of an apparatus of power. The alternating current that uses daily is mixed in the voltage on pure resistor load electric current is inphase, namely phasic poor Q = 0° , if graph 1(a) place is shown; Alternating current concerns in the voltage on pure capacitance load and electric current is 90°(q =90°) of voltaic lead voltage, if graph 1(b) place is shown; Alternating current concerns in the voltage on pure inductance load and electric current is 90°(q = -90°) of voltaic lag voltage, if pursue,1(c) place is shown.

 

Graph the voltaic voltage on load of 1 different property concerns

 

The definition of power factor is: (1)

 

The power of have rendered great service on resistor load is inspected namely in power, namely both is equal, so power factor F=1. And the electric current on pure capacitance and pure inductance load and voltage are phasic poor 90° , so so power factor F=cosq = Cos90°=0, the power of have rendered great service that goes up in pure capacitance and pure inductance load namely is 0.

 

Can see a problem from here, it is a power source likewise, the size of the power that to not congenial load its output and property are different also, because this can say laden quality,deciding the output of power source. Change character, the output of power source does not depend on the itself of power source, the water supply current that resembles a water tower depends on the open degree of faucet.

 

Can see from the discussion above, power factor is a parameter of token load property and size. And say a load has a kind of quality only commonly, have an Id number only like a person same. This kind of property is from laden input end looks surely really, call laden power input factor. A laden circuit was finished, its power input factor also was decided.

 

For instance UPS serves as in front the load of town report or dynamo, the UPS that for instance 6 pulse commutate inputs, factor of its power input is 0.8, no matter in front it is town report electrified wire netting or dynamo, ask to input 100kVA for instance inspect in power, need the power of have rendered great service that demands 80kW to the power source in front and 60kvar without result power. If the power input factor of UPS is 0.6, of the power of have rendered great service that demands 60kW with respect to the power supply that needs forward range and 80kvar without result power. Allocate like such output, power source is “ has no right in front ” decides.

 

2, the factor of parameter —— laden power of capacity of token UPS output

 

1.Laden power factor is outputted for “ by miscall power factor ”

 

UPS cannot be made man-to-manly, also want to give a batch according to using the form of electric equipment and dimensions prefabricate currently beforehand or the machine of factor of a few batches of different power and power standards, with equipment market spot sale. Prefabricate gives a batch or the basis of a few batches of UPS is laden power factor. When the laden power factor when UPS and laden power input factor are equal, call match completely, UPS can output full power. Encounter when matching load, must fall the forehead is used. Graph 2 show the concern that gave factor of UPS laden power and factor of laden power input.

 

The relation of factor of laden power of graph 2 UPS and factor of laden power input

 

Some call the laden power factor of UPS by accident the output power factor of UPS. The origin of this kind of misunderstanding thinks probably since UPS has power input factor to have output power factor certainly, come so the property of UPS has two kinds, looking from the input is a kind of property, looking from output is another kind of property, misunderstood the uniqueness of circuit property. Since be the output power factor of UPS, the place before be like is narrated, if UPS has the capacity that outputs 100kVA, ought to fall to be able to give out in the condition of any laden property so the power of have rendered great service that power factor place points out and without result power. The numerical value that is called to output power factor for instance is 0.8 when, of the power of have rendered great service that 80kW can give out below the condition in any laden property and 60kvar without result power. But not be actually such. Often appear for instance this kind of circumstance, when taking linear load for the 100kVA UPS of 0.8 when laden power factor, can turn because of overload bypass, this is firstly; Secondly, should measure the discovery when UPS outputs end with power factor meter, when taking linear load its power is because of numerical value 1, when the IT that takes input of wave of diode commutate filter is laden its power factor is worth is 0.7, how to also go out not to come 0.8! What actually these two kinds of circumstances measure is laden power factor, factor of alleged output power 0.8 won’t appear at all, when unless take power input factor,be the load of 0.8, but the also remains load power factor that measures in those days. Namely, want to take load to measure only, those who measure is laden power factor. Come so, the ability when taking load only can be measured so that the “ of UPS outputs power factor ” , have the IP=0 of output electric current of result power P at this moment, inspect the IS=0 of output electric current in power S, although the voltage UP of both is mixed,US is 0, but according to type (1)

 

 (2)

 

This result is an irrational number. Test of power factor meter is not measured at all give any values. That is to say ” of factor of power of output of so called “ does not have any operation sexes.

 

Factor of 2. laden power decides an element really

 

When factor of so laden power is taking linear load for the 100kVA UPS of 0.8, why to give give 80kW? General the design of UPS of labour frequency machine below this kind of circumstance is a basis power of rated have rendered great service chooses inverter, and be assumed without result power part by the capacitor C at the back of inverter, if pursue,3 are shown. The inverter power in the graph chooses even if according to set of laden power factor. Here is with laden power factor is the 100kVA UPS of 0.8 to be the number of the exemple. Inverter is the power canal that chooses according to 80kW, the capacity of capacitor C is a basis of output those who do not have make choice of of result power 60kvar (the capacity) that when still needing to add filter wave additionally of course, needs. The sensibility that goes up without result power load does not have the look sex that because be in,the output of C of the capacitance when matching load completely does not have result power QC and load to go up absolute value of result power QL is equal and the symbol is contrary, completely complementary (direct look decreases) , namely: QC-QL=0

 

And the loop electric current that C and L form does not shed classics inverter, do not shed classics inverter without result electric current namely, UPS is made below condition of this kind of set.

 

Graph the main circuit structure that UPS of machine of frequency of 3 average worker worker and load match a circumstance to fall

 

Fall in the requirement that matchs completely so, laden power factor is the 100kVA UPS of 0.8 to be able to carry load of the power of have rendered great service 80kW and 60kvar entirely without result power. Be in namely when the laden power factor of UPS and laden power input factor match completely, the power that gets on load is:

 

 (3)

 

If the laden power factor of laden power input factor and UPS is unequal, how is case met again? For instance the load from the back is linear load, namely =1 of laden power input factor, this kind of case often appears in UPS to take false load to study machine situation, if pursue,4 are shown. Have a very big distinction here, the inductance part in load was done not have. This caused inverter from the back the also cannot offer to laden end again without result power situation of capacitor C. Because the capacitive reactance XC of 60kvar is:

 

 (4)

 

From on type can see, inverter is outputted above all shunt-wound a reactance that is less than 1W, if let inverter output end to build the voltage of a 220V, want to offer IC of an electric current to capacitance C above all, the size that its are worth is:

 

 (5)

 

And the voltaic IINV that original inverter can offer is:

 

 (6)

 

Very apparent, must subtract from inside inverter output electric current the afore-mentioned electric current that allow a gender, the rest of just is Ir of laden due electric current, namely:

 

 (7)

 

The power Pr that can get on load right now so has only:

 

Pr =241A´220V»53kW (8)

 

Graph the main circuit structure that UPS of machine of frequency of 4 average worker worker and linear load do not match a circumstance to fall

 

Type of computation of diligent perhaps rate reachs similar result:

 

 (9)

 

Because this is laden,power factor is for the 100kVA UPS of 0.8 when the belt is linear and laden, can give out only the power of 53kW, in before in the machine more than the ground proved this conclusion. When the laden power factor that is not equal to UPS when laden power input factor that is to say, UPS must fall the forehead is used. This is common law, the UPS of factor of laden to differring of course power is having those who differ to fall frontal value.

 

3.To the misapprehensive harm of UPS power factor

 

The “ that considers as laden power factor UPS by accident as a result of some users outputs power factor ” , not only will attributive relation made a mistake, and derivative still a concept that exists far from. Since be the ” of output power factor of “UPS, so the output power of UPS must be subject to value of this power factor, the output power ” of 80kW also should give out when “ power factor is taking linear load for the 100kVA UPS of 0.8 that is to say. If this kind of misunderstanding is individual user merely, bring about the contradiction of user and supplier respect at most. But if be the person that establish a standard,be immersed in this error, the harm is UPS manufacturer of the whole nation.

 

It is the high-power UPS of the entrance so for instance, in the discovery when taking linear experiment load power factor is the 100kVA UPS of 0.8 not to give give 80kW, the product that considers as manufacturer then is unqualified, also say not to understand a reason in together with manufacturer, be forced to increase the power of inverter then, it is that is to say in inverter must also 60kvar include without result power, namely:

 

 (10)

 

The cost of inverter of aeriform lieutenant general raised 20% , but the drive circuit of inverter also upgrades accordingly than needing, that is more than 20% . All countrywide manufacturer must be dealt with according to this, this influence area is large! Come so, the output power of 80kW is to give out came, regrettablly is F of laden power factor not be 0.8, because be immersed in the manufacturer of the error,be won’t of will original 60kvar make any changes without result power, still withheld the capacitor of 60kvar namely, pressing the original design to F of laden power factor so, became:

 

 (11)

 

Of course, should output only enough 80kW, be worth unmanned also attend to as to right now power factor. If true somebody saw this, think the UPS of this 100kVA wants to give out only 68.4kW amounts to mark!

 

Very apparent, such change is not should, coming is the interest that harmed manufacturer, 2 will also do not accord with scientific reason, it is because of misapprehensive reason factitious ground thinks to be done so only. Even some saying: Most person agrees to do that to be opposite so. Wanting the problem that knows science do not rely on to lift watch to be solved definitely, the apple of free falling body should fall on the ground namely, watch of again much person raise one’s hand also won’t fly to the sky definitely.

 

With what laden power factor stands side by side one is measured even if UPS outputs the harmonic distortion factor of voltage, confuse sth with sth else of some general both, the harmonic distortion factor that thinks to want to output voltage only achieves a requirement, factor of so laden power also knew. Wave of harmony of factor of laden in products plan power is actually lack fidelity although some are contacted, but not be a thing, respective consideration is different. Harmonic distortion factor is just like is to measure this dress to be done handicraft work is well, sutural close, the style is good. And what power factor meter shows is male dress or female dress, it is much more good-sized dress, etc. So these two index and cannot say turkey to one and bazzard to another, abandon even among them one of.

 

What cannot make a person be at ease more is to some of reader still thinks power factor is percentage up to now, often hear somebody to ask: How much is the power input factor of your UPS 100 minutes of values? This can see clearly from the computation above, power of have rendered great service and having result power is orthogonal relation. From type (11) also can see inspect mix in power of power, have rendered great service without result power 3 person the relation between is the significance that the right-angled triangle draws a bowstring. So power of have rendered great service is mixed having result power is cannot add directly decrease. Than the example of as above face, if 80kW regard as 80% , so 60kvar is 60% , come so power of have rendered great service and add in without result power even if 140% , it is incorrect apparently. If this the basiccest basic idea is done not clear, other idea understood very hard!