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How to select voltage and protection and insulation
- Feb 08, 2017 -

1, explosion-proof electrical voltage levels

In recent years, due to energy needs, in order to reduce energy loss in the line, improve voltage level trend is obvious: explosion-proof motor used in underground elections 3kV; petrochemical industry and explosion-proof motor used in coal mine main well ventilated selected lOkV gradually running out, power is also getting smaller and smaller, some even received 110~160kW production factory, lOkV orders. Made lokV manufacturing costs to such a small power increase, wire processing is also more difficult.

When low voltage explosion-proof motor frequency at 60Hz, its best to 460V rated voltage, domestic manufacturers of explosion-proof motor is easy to 50Hz derived products.

2, explosion-proof electrical protection class

Protection class by adding two numbers after the IP. 1th digits from the left is dust-proof, the 2nd digit is waterproof. Sometimes the buyer for the purchase price, or is the protection class do not quite understand, sophomore IP54 sites selected for explosion-proof motor of IP44, even of explosion-proof Motors IP23. For example drag mill explosion-proof motor used in power station, you must choose the IP54.

3, explosion-proof electrical insulation class

Mention of insulation levels, will be involved in explosion-proof motor temperature rise. In practice there are two problems with supply and demand both sides should reach a consensus:

① temperature-rise limits the current domestic production of high and low voltage explosion-proof motor, more than 90% are class f insulated. In order to improve the life of explosion-proof motor, 90% manufacturer indicates in the sample selection f class insulation, temperature rise class b limit checking ″. Class b insulation allows the highest temperature is 130 ° c, f-class is 155. Consider 40 ℃ environment temperature and manufacturing processes and materials of the fluctuations in total 5 c 10 c, temperature rise class b insulation explosion-proof motor factory-specified limit of 80K. While the f class insulation manufacture of explosion-proof motor, factory limits when you press b, temperature-rise limits should be 90K (underground explosion-proof motor is 95K).

② class h insulation class h insulation allows the temperature to 180 c. Press h to level design and manufacture of explosion-proof motor, bearings and grease in the country is not yet common. Class h insulation of windings, for factory is not difficult, the key is the high temperature bearings. Therefore, not in the case of last resort (such as 60 ℃ ambient temperature or volume be limited cases of explosion-proof motor), try not to use class h insulation explosion-proof motors.