Samlex America SAM-3000-12 - Manual (Page 7)

4 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 5
SECTION 2 | Description, Features &
Principle of Operation
SECTION 2 | Description, Features &
Principle of Operation
The output waveform of the inverter is a Modified Sine Wave. In a Modified 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-
fied Sine Wave. check with the manufacturer of the device for suitability of powering
with modified 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, flashlights, 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 modified Sine-Wave Voltage with a “true rms” Voltmeter
As mentioned above, Modified 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 Modified
Sine Wave. If this general-purpose voltmeter is used to measure Modified Sine Wave volt-
age, it will indicate a lower value (96 VAC to 104 VAC). For accurately measuring the voltage
of a Modified Sine Wave, use a voltmeter which is designed to measure “True RMS Values”
like Fluke 87, Fluke 8060A, Fluke 77 / 99, Beckman 4410 etc.
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