Watt question
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Watt question
Ive got a small compressor I'm gonna use to run a train horn and I need a power inverter that will push it does anybody know how many watts I should need?
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#8
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I don't think it's as simple as "watts." Watts is volts x amps, but done microsecond by microsecond. With resistive loads (lights) volts and amps are always in phase, but a compressor is a big inductive load, so the amps will be WAY out of phase (you will have a "power factor" less than 1.0). Put another way, a 120 watt light pulls 10 amps of 12 volts. But a compressor rated at 120 watts might have to pull 25 amps (out of phase) to get 120 watts. (Big inductive loads are often rated in "VA" (volt-amperes) instead of watts for this reason.)
Add to that the quirky inefficiencies of inverters, and figuring out the size of an inverter for a given wattage compressor is anything but trivial.
Add to that the quirky inefficiencies of inverters, and figuring out the size of an inverter for a given wattage compressor is anything but trivial.
#9
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I don't think it's as simple as "watts." Watts is volts x amps, but done microsecond by microsecond. With resistive loads (lights) volts and amps are always in phase, but a compressor is a big inductive load, so the amps will be WAY out of phase (you will have a "power factor" less than 1.0). Put another way, a 120 watt light pulls 10 amps of 12 volts. But a compressor rated at 120 watts might have to pull 25 amps (out of phase) to get 120 watts. (Big inductive loads are often rated in "VA" (volt-amperes) instead of watts for this reason.)
Add to that the quirky inefficiencies of inverters, and figuring out the size of an inverter for a given wattage compressor is anything but trivial.
Add to that the quirky inefficiencies of inverters, and figuring out the size of an inverter for a given wattage compressor is anything but trivial.
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