Quote:
Originally Posted by Ether
Is the compressor motor startup current at 100psi specified anywhere? Has anyone measured it with a current probe and a scope?
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Good idea, Russ. I will try that tonight and report results. My team has three types of compressors on hand so I'll attempt to measure starting surge current for each.
-------edit after testing--------
We tested three compressors, using an oscilloscope and current probe to measure (1) initial peak surge current, (2) average current draw during charging, and (3) time to full charge. The test system capacity was 48 cubic inch (3x Clippard AVT 32-16). In each case the duration of the initial surge current was ~0.05 second, rising to its peak in about 0.005 second and decaying exponentially to steady value after that. I have attached a typical oscilloscope plot of the compressor current, 50 seconds full horizontal scale and +/- 40 Ampere full vertical scale. This plot is for the Thomas compressor; other plots are similar in form but differ in their initial peak surge, average current draw, and time to full charge as summarized below.
Viair 90C: initial peak surge 18 Ampere, average current draw during charging 12 Ampere, time to full charge 40 seconds.
Thomas 405ADC38/12: initial peak surge 32 Ampere, average current draw during charging 10 Ampere, time to full charge 36 seconds.
Viair 250C-IG: initial peak surge 40 Ampere, average current draw during charging 9 Ampere, time to full charge 33 seconds.
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Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)