I asked this in the electronic section and been recommended to take it here instead. I've come to this site to ask some advice. I recently bought a 2 HP (1500 watt) workshop cyclone dust extractor, and I became suspicious about its rating.
So I ran it with minimal loading, so just the filter but no additional piping and measured the AC power input (or output from the mains socket) this measures as 1000 watts. (240 volts). Then when I covered the inlet (to increase the air flow restriction) the current draw from the outlet reduced to ~800 watts.
I've been told that the motor rating may not be reflected in the current draw as it simply may not be set up to be fully loaded, and by throttling the inlet I infact actually just reduce the load, (not sure how this works).
I've initially been thinking the motor ISN'T a 2hp motor, but maybe this is irrelevant?
On another point, I bought an anemometer to check the airflow. It gives me readings suggesting that it's only sucking about 80% of the stated. so about 500cfm vs 600cfm. Does anyone have any good ideas on how I can check the calibration of my anemometer?