Xantrex Technology SW Series Power Vs. Efficiency, Page, SW3024E / SW3048E, SW4024 / SW4048

OPERATION

POWER VS. EFFICIENCY

There are two primary losses that combine to create the efficiency curve of the SW Series inverter. The first is the energy that is required to operate the inverter at full output voltage while delivering no current. This is the no load or idle power. At low power levels, the idle power is the largest contributor to efficiency losses. At high power, the largest source of loss is a result of the resistance in the transformer and power transistors. The power lost here is proportional to the square of the output power. For example, losses at 2000 watts will be four times higher than losses at 1000 watts. This graph represents a typical inverter’s efficiency while operating resistive loads. Inductive loads such as motors are run less efficiently due to the impact of power factor losses.

	100%
	90%
	80%
	70%												SW3024E / SW3048E
Efficiency	60%														SW4024 / SW4048
	50%										S							SW4548E			SW5548
						SW2512					W
	40%										2
											6
											1
	30%										2
											E
	20%
	10%
	0%
	0	250	500	750	1000	1250	1500	1750	2000	2250	2500	2750	3000	3250	3500	3750	4000	4250	4500	4750	5000	5250	5500
											Power (VA)

Figure 19, Trace™ SW Series Efficiency Curves

The SW Series offers an extremely good efficiency curve. The inverter reaches high efficiency at very low AC load levels, which is important because the inverter often spends the majority of the time at the lower power range. The high efficiency is maintained over a wide power range. Only when operating at high power levels at or above the continuous power levels does the efficiency begin to drop off. Since this usually only occurs for short periods of time, the impact may be negligible.

If your application involves the inverter powering heavy loads for significant periods of time, selecting a model with a higher continuous power rating and a higher DC input voltage would improve the operation of the system. Since the low power efficiency of all the SW Series is extremely good, oversizing the inverter does not reduce system performance.

 2001 Xantrex Technology, Inc.	Telephone: 360/435-8826	SW Series Inverter/Charger
5916 - 195th Street N. E.	Fax: 360/435-2229	Part No. 2031-5
Arlington, WA 98223	www.traceengineering.com	Rev. C: February 2001

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