Andymark 1.1 Compressor Data

[Richard Wallace]

Originally Posted by cbale2000

Continuous = 100% duty cycle, at least in the case of the Thompson.

The compressor mentioned earlier in this thread is the Thomas (not Thompson) model 405ADC38/12, which was the standard FRC kit compressor for many years. That compressor is definitely NOT rated for 100% duty.

Its motor's rating is ~75 Watts, so it can draw 75/12 = 6.3 Ampere continuously. This is significantly less than the power consumed when the compressor is running -- then it draws about 11 Ampere, so it is consuming 132 Watts.

Some of the power consumed actually compresses air, and the rest is lost as heat in the motor coils, or as friction in the pump, or in other ways. If the compressor's continuous rating is limited by the size of the motor, then its duty will be about (6.3/11)^2 = 33%.* However, most compressors of this type are limited by the size of the pump; experience with this compressor in FRC application suggests its duty limit is less than 33%.

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*Motor heating is roughly proportional to the square of current draw, because most of the heat comes from resistive losses in the coils.