Samlexpower PST-1000-12 Owner's manual - Section 2 |
8 | SAMLEX AMERICA INC.
theinverter.TheinvertercanbesizedbasedontheActivePowerrating(Watts)without
creating overload.
Reactive Load:Adeviceorappliancethatconsistsofacombinationofresistive,induc-
tiveandcapacitiveelements(likemotordriventools,refrigerationcompressors,micro-
waves,computers,audio/videoetc.).ThesedevicesrequireApparentPower(VA)from
theinvertertooperate.TheApparentPowerisavectorialsumofActivePower(Watts)
andReactivePower(VAR).The inverter has to be sized based on the higher Apparent
Power (VA).
output Voltage Waveforms
Fig. 2.1: Pure and Modified Sine Waveforms
TheoutputwaveformoftheSamlexPSTseriesinvertersisapuresinewavelikethe
waveform of the grid power. Please see sine wave represented in the fig. 2.1 that also
shows modified waveform for comparison.
Inasinewave,thevoltagerisesandfallssmoothlywithasmoothlychangingphase
angleandalsochangesitspolarityinstantlywhenitcrosses0Volts.Inamodifiedsine
wave,thevoltagerisesandfallsabruptly,thephaseanglealsochangesabruptlyand
itsitsat0Vsforsometimebeforechangingitspolarity.Thus,anydevicethatusesa
controlcircuitrythatsensesthephase(forvoltage/speedcontrol)orinstantaneouszero
voltagecrossing(fortimingcontrol)willnotworkproperlyfromavoltagethathasa
modified sine waveform.
Also,asthemodifiedsinewaveisaformofsquarewave,itiscomprisedofmultiple
sinewavesofoddharmonics(multiples)ofthefundamentalfrequencyofthemodified
sinewave.forexample,a50Hzmodifiedsinewavewillconsistofsinewaveswithodd
harmonicfrequenciesof3rd(180Hz),5th(300Hz),7th(420Hz)andsoon.Thehigh
seCtIOn 2 |
General Information
TIME
180
160
140
120
100
80
60
40
20
0
20
40
60
80
100
120
140
160
180
Modified Sine
Wave sits at
ZERO for some
time and then
rises or falls
Modified Sine Wave
Sine Wave
Pure Sine Wave
crosses 0.0V
instantaneously