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Heavy duty tire pump - 30 Amps 350 W power inverter - 32 Amps Auto cigarette lighters typically have a 20A fuse. It may take 10 minutes or more to blow at 25% over it's rated curent. Source: Fuses | bcae1.com |
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See Also: www.donrowe.com/inverters/usage_chart.html www.eurobatteries.com/sitepages/choosinginverter.asp Common Household Appliance Energy Use
* See Volt-Amp to Watt conversion below See Also: Charging Volts and Amps for consumer electronics.
UPS - Uninterruptible Power Supplies:
Typically 100 watts of supplied UPS power will run 100 watts of incandescent lightbulbs, but only 71.4 watts of a typical capacitor input switching type computer power supply, and nearly 100 watts of a PFC computer power supply.
Batteries will last longer (more discharge cycles) if discharged at a lower rate. Battery RunTime Conext Battery Backup 300VA/180 Watts - 170 Watts 4 min 100 Watts 11 min. 500VA/300 Watts - 201 Watts 4 min/ 100 Watts 15 minAPC
True Power (watts) = Volts (RMS) x Amps (RMS) x Power Factor where V = Volts, A = Amps pf = the power factor of the load, applies to all electrical loads.
A standard 120 V household current swings between +170 V and -170 V in a sine wave pattern. the RMS value (root-mean-square) is 1/SQRT(2), or about 0.707 times the peak. This despite the fact that the average value of a sine wave is about 0.637 times the peak. In the case where the load acts purely resistive, such as that of an incandescent light bulb, heater or a PFC (Power Factor Corrected) switching power supply, the pf will equal 1 or nearly 1. For all other cases, the pf will vary between 0 and 1, and for a typical capacitor input switching type computer power supply, a power factor of about 0.714 is usually exhibited. Typically 100 watts of supplied UPS power will run 100 watts of incandescent lightbulbs, but only 71.4 watts of a typical capacitor input switching type computer power supply, and nearly 100 watts of a PFC computer power supply. Example: A typical capacitor input switching computer power supply is 200 watts. The VA output equivalent can be calculated as follows:
watts = VA * pf, or, VA = watts / pf so 280 VA of the UPS supplied power will be needed by the 200 watt computer power supply at full draw. Another faster way to express this, is
Computer Power Supply in Watts * 1.4 = UPS VA AC Watts to DC Amps AC Watts divided by 12 x 1.1 = DC Amps Some appliances or tools, such as ones with a motor, require an initial surge of power to start up ("starting load" or "peak load"). Once started, the tool or appliance requires less power to continue to operate ("continuous load"). So, power inverters (DC battery to AC) and generators are sometimes rated by peak and continuous load. Source: The Volt-Amp to Watt conversion information above came from a web site named Sutton Designs (www.suttondesigns.com/doctext/pf.html) which is no longer available.
DC Inverter: e.g. It will require 10 amp hours of battery to operate a 100 watt bulb for 1 hour. The battery rating should be twice this (i.e. 20 amp-hours for maximum battery life and performance.
Meters: Amp, watt, volts
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