Which Insulation Class Is Better F Or H

Class a is an older form of insulation utilizing organic varnishes and resins available many years ago.

Which insulation class is better f or h.

Insulation class b f h maximum winding temperature 130 c 155 c 180 c 0 40 120 130 155 145 165 180 c 20 maximum ambient temperature minimum ambient temperature 30 minimum ambient temperature 10k 105k 40 c class f b 155 c 80k safety margin 25k 150 c ptcs setting 2 c0 2 c0 2 c0 regal beloit bv mors 2. Nema insulation classes do away with guessing and give the motor manufacturer a defined framework to operate in. Class 150 or 130. Class c insulation consists of materials or combinations of materials such as mica porcelain glass quartz with or without an inorganic binder beware a few older applications used asbestos.

Example a motor operating at 180 o c will have an estimated life of. So if we look at a class f insulated motor which will be happy running at 155 c and then subtract 30 c we get a surface temperature of 125 c. The electrical insulation system is sometimes referred to as insulation class or thermal classification the different classes are defined by nema underwriters laboratories ul and iec. 8500 hours with class f insulation.

Only 300 hours with class a insulation. Average winding temperature rise. Each insulation class has a margin allowed to compensate for the motor s hot spot. Similarly a class h system operating at a class f temperature rise will provide the same life expectancy as a class f system operating at a class b temperature rise.

The hot spot is a point at the center of the motor s windings where the temperature is higher. These insulation classes were established to meet motor temperature requirements found in industrial applications. 1800 hours with class b insulation. Other materials or combinations of materials may be included in this class if by experience or tests they can be shown to be capable of operation at temperatures above the class h limit.

There are basically four classes of insulation a b f and h class f being the most commonly used. Tens of thousands of hours with class h insulation. Moving from an insulation system class f with a hotspot of 140 c to a hotspot of 160 c the s9 ratings are able to be increased by 7 with an improvement in design of. As can be seen from the above table hot spot over temperature allowance for a b f and h are respectively 5 c 10 c 10 c and 15 c.

Hot spot temperature rise.