Samlexpower SAM-250-12 - Device Compatibility with Modified Sine Wave; Accurate Voltage Measurement

4 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 5
SECTION 2 | IntroductionSECTION 2 | Introduction
TheoutputwaveformoftheinverterisaModiedSineWave.InaModiedSineWave,
thevoltagewaveformconsistsofrectangularpulsesthatapproximatesinewavepulses
of a Pure Sine Wave. The voltage rises and falls abruptly at a particular phase angle and
sits at 0 Volts for some time before changing its polarity. In a Pure Sine Wave, the voltage
rises and falls smoothly with respect to phase angle and the voltage changes its polarity
instantly when it crosses 0 Volts.
!
Caution!
Certain devices (few examples given below) may malfunction when powered from Modi-
ed Sine Wave. Check with the manufacturer of the device for suitability of powering
with Modied Sine Wave:
• Devicesutilizingzerovoltagecrossingfortimingcontrol:Someclocksusedin
consumer electronic items (will not keep accurate time)
• DevicesusingmodulationofRFsignalsonAClinesduringzerocrossing
e.g. X-10 System for Home Automation
• DevicesutilizingTriacbasedphasecontrolfortransformerlessvoltagestep
down e.g.:
• Smallbatterychargersforhandtools,ashlights,night-lights,shaversetc.
• Variablemotorspeedcontrolinhandtools
• Lightdimmers
• Temperaturecontrollerse.g.TemperatureControlledElectricBlankets
• Devicesusinghighcapacitancebasedvoltagemultipliersforgeneratinghigh
voltage (will create very high surge currents) e.g.:
• PhotographicStrobeLights
• LaserPrinters
Measuring Modied Sine-Wave Voltage with a “True Rms” Voltmeter
Asmentionedabove,ModiedSineWavevoltageisatypeofsquarewavethathasanRMS
(Root Mean Square) value of 115 VAC in this inverter. A general-purpose AC voltmeter is
calibratedtoaccuratelymeasuretheRMSvalueofaPureSineWaveandNOTofaModied
SineWave.Ifthisgeneral-purposevoltmeterisusedtomeasureModiedSineWavevolt-
age, it will indicate a lower value (96 VAC to 104 VAC). For accurately measuring the voltage
ofaModiedSineWave,useavoltmeterwhichisdesignedtomeasure“TrueRMSValues”
like Fluke 87, Fluke 8060A, Fluke 77 / 99, Beckman 4410 etc.