Samlexpower PST-1000-12 Owner's manual - Section 2 |
6 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 7
effectisatendencytocanceleachother.Hence,inacircuitcontainingbothinductances
andcapacitances,thenetReactance (X) will be equal to the difference between the
values of the inductive and capacitive reactances. The net Reactance (X) will be inductive
if X
L
>X
c
and capacitive if X
c
>X
L
.
impedance, Z: It is the vectorial sum of resistance and reactance vectors in a circuit.
ActivePower(P),Watts:Itisdenotedas“P”andtheunitis“Watt”.Itisthepowerthat
isconsumedintheresistiveelementsoftheload.AloadwillrequireadditionalReactive
Power for powering the inductive and capacitive elements. The effective power required
wouldbetheApparentPowerthatisavectorialsumoftheActiveandReactivePowers.
Reactive Power (Q), VAR: Is denoted as “Q”andtheunitisVAR.overacycle,thispower
is alternatively stored and returned by the inductive and capacitive elements of the load.
It is not consumed by the inductive and capacitive elements in the load but a certain
valuetravelsfromtheACsourcetotheseelementsinthe(+)halfcycleofthesinusoidal
voltage(Positivevalue)andthesamevalueisreturnedbacktotheACsourceinthe(-)
halfcycleofthesinusoidalvoltage(Negativevalue).Hence,whenaveragedoveraspan
ofonecycle,thenetvalueofthispoweris0.However,onaninstantaneousbasis,this
powerhastobeprovidedbytheACsource.Hence, the inverter, AC wiring and over cur-
rent protection devices have to be sized based on the combined effect of the Active and
Reactive Powers that is called the Apparent Power.
Apparent (S) Power, VA:Thispower,denotedby"S",isthevectorialsumoftheActive
PowerinWattsandtheReactivePowerin“VAR”.Inmagnitude,itisequaltotheRMS
valueofvoltage“V”XtheRMSvalueofcurrent“A”.TheUnitisVA.Please note that
Apparent Power VA is more than the Active Power in Watts. Hence, the inverter, AC wir-
ing and over current protection devices have to be sized based on the Apparent Power.
Power Factor, (PF):Itisdenotedby“Pf”andisequaltotheratiooftheActivePower
(P)inWattstotheApparentPower(S)inVA.Themaximumvalueis1forresistivetypes
ofloadswheretheActivePower(P)inWatts=theApparentPower(S)inVA.Itis0for
purelyinductiveorpurelycapacitiveloads.Practically,theloadswillbeacombinationof
resistive,inductiveandcapacitiveelementsandhence,itsvaluewillbe>0<1.Normally
itrangesfrom0.5to0.8.
Load: electrical appliance or device to which an electrical voltage is fed.
Linear Load: Aloadthatdrawssinusoidalcurrentwhenasinusoidalvoltageisfedtoit.
Examplesare,incandescentlamp,heater,electricmotor,etc.
non-Linear Load:Aloadthatdoesnotdrawasinusoidalcurrentwhenasinusoidalvolt-
ageisfedtoit.forexamplenon-powerfactorcorrectedSwitchedModePowerSupplies
(SMPS)usedincomputers,audiovideoequipment,batterychargers,etc.
Resistive Load:Adeviceorappliancethatconsistsofpureresistance(likefilament
lamps,cooktops,toaster,coffeemakeretc.)anddrawsonlyActivePower(Watts)from