Dennis Reece

One thing I forgot to add is DO NOT USE COMPRESSOR DUTY MOTORS unless you plan to do one for one conversion for gas engine replacement since they are peak rated!!!! Those motors are already factored into the load profile for compressors. They are NOT continuous rated at the power level they state. They will say a word phrase called "special" in the the run duty box instead of continuous. That is just a fancy term for peak power rating. So a 5 Hp compressor electric motor is the same as a true 3 HP electric motor or 5 HP gas engine. The price and weight of the motor also reflects this as you will often see that compressor duty motors are quite a bit cheaper and lighter in weight than the regular rated electric motors. Hope that helps!! Have a good thanksgiving!!!

Electric motor HP rating is a thermal contraint based on a load needing that HP from the motor continuously at a temp of 40C ambient. Requesting more power from the motor for long periods will either burn it up or shorten it's life span. Gas engine horsepower is based on its maximum capability with no overlaod capability like electric has. See the difference? With such a characteristic you can spec an AC induction motor for lower horsepower in some specific applications because not only does the torque jump up in overload, but the speed change is very minimal, so you get more horsespower out of the motor when it's being overloaded. You can only do this for loads that do not require a constant HP over long periods. Like if a load is 5 HP at all times, then a 3 HP AC motor will burn up. You can only spec an AC motor with lower horsepower for periodical loads that will have rest periods in between the overload periods such that the motor's average temperature is the same of though the motor is ran at its full HP rating at all times. An example would be like log splitter since each piece of wood will need different levels of power, but you may occasionally run into a knot that will require more power beyond the motor's rating. Here is the conversion: 3 HPeletric = 5 HPgas 5 HPe = 8 HPg 7.5 HPe = 10 HPg 10 HPe = 15 HPg CONVERSION VALID ONLY FOR PERIODICAL LOADS!!!