What are different types of insulation classes?
Insulation may be grouped into the following recognised classes:
- Class A. Class A insulation consists of materials such as cotton, silk and paper when suitably impregnated or coated or when immersed in a dielectric liquid such as oil.
- Class B.
- Class C.
- Class E.
- Class F.
- Class H.
Which is Better Class B or Class F insulation?
With modern designs, a ‘Class B’ temperature rise is readily achievable. Therefore Class F insulation with a Class B temperature rise gives us a thermal margin of 25°C, potentially increasing the life of the motor by up to 5 times….Too hot to handle?
| A= | 70°C |
|---|---|
| B= | 90°C, |
| F= | 115°C. |
What is class E insulation?
Class-E Insulation: Class-E insulations can withstands a temperature of up to 120°C.
What is class 155 insulation?
The class number = the maximum °C of the transformer insulation
| NEMA Insulation Class | NEMA Letter Designation | Maximum Allowable Temperature Rise |
|---|---|---|
| 105 | A | 50 |
| 130 | B | 80 |
| 155 | F | 105 |
| 180 | H | 125 |
What are the different classes of insulation used?
There are basically four classes of insulation – A, B, F and H – class F being the most commonly used. These insulation classes were established to meet motor temperature requirements found in industrial applications. Class A is an older form of insulation utilizing organic varnishes and resins available many years ago.
What’s the maximum temperature for Class C insulation?
Class-C Insulation: Class-C insulations withstand a temperature of up to 180°C or higher. It is typically made of 100% inorganic material. As explained above, electrical insulation is classified with its maximum allowable temperature.
What does the F stand for in insulation class?
Thermal imaging can also be a powerful tool for measuring motor temperature. You may see the use of a temperature rise letter used along with the insulation class, such as an F/B motor. The F refers to the insulation class for the windings, while the B refers to an 80°C rise (the maximum temperature rise for Class B is 80°C).
How is the insulation class of a motor determined?
The motor’s ambient temperature, internal temperature rise, the altitude (>3300 Feet) and the service factor will be the determining factors in choosing the class of insulation. The ambient temperature factor is determined by measurement of ambient air surrounding the motor.