Air Compressor Motors

If you put a smaller motor pulley on it and run it slower....

Otherwise, no. The calc is easy: 5 < 7.5.

It's a very rare occasion that I disagree with Tornado, and I do so now with tongue partly in cheek.

If you can find a 5 HP motor with a service factor of 1.5 or more, you would be able to do it without modifying the compressor. Of course, the life of the motor will be correspondingly shorter, etc.

Or, get a Lyndoor Industries Double-Trouble™ 2.0 SF motor.

I'm going to put you in for a raise!

I just want a -10% commission for each one I don't sell.

Not if the motor overload trip device is correctly set.

If it isn't, then it may, for a short time until it burns out.

Ed might be selling a 454 soon that will have more than enough power to drive your compressor

When the epa starts smogging lawnmowers and air compressors you might be in trouble though.

Good point

Motor will draw high current and will trip on instantaneous current high on start or on thermal overload during running.

The electric motor that I want to use is a Leland 5.0 HP, 1740 RPM, 220Vac, 1 p.h., cap start, cap run. However, if you figure it out mathematically the motor is a 6.0 HP. It has a 1.15 Service factor. The 2-stage 3 cyl pump that I want to use with this motor is designed to run at 840 RPM. What do you think?

Install a variable pitch pulley on the motor and set the pitch (by opening or closing the belt groves) to the amperage needed to run the motor at its rated amperages. Increase the run cap 10% which will again lower the amperages slightly to keep it with in its service factor ratings.

Or but a 7.5 HP motor that is suited for the compressor.

Thanks, I will try this.

The most important information required is the rated capacity (Nm3/hr) and discharge pressure of compressor. You have to sacrifice either one of these two or both for using 5 hp motor. So, please decide first, what are your exact requirement?

The safest and easiest way to do it to reduce the speed by 5/7.5 ratio. Change from 840 rpm to 560 rpm. It can be done in two ways. (1) Change pulley diameter for increased ratio between motor and compressor. (2) Use VFD. VFD is costlier, but has a distinct advantage of variation according to requirment.

When you run at 560 rpm, you will get 2/3rd of capacity at rated pressure. If you want use more, pressure will reduce in proportion to increase in flow rate from 2/3rd.