When selecting explosion-proof motors, only high-quality and accurate models can ensure the normal operation of the machine. So, what factors should be considered when choosing an explosion-proof motor?
1. After the voltage, frequency, and speed are determined, select the installation factor K to determine the motor power according to the load driven by the explosion proof motor and the power supply network condition. The installation size can be found from the motor sample by the installation method, or the electric frequency converter can be selected from the sample first.
2. Confirm whether the technical indicators of the explosion proof electric motor meet the requirements (the supplier and the demander will finalize in the technical agreement). For the wound rotor motor, in order to select the matching starting and speed regulation system, the supplier also needs to provide the values of the rotor voltage U2 and current I2.
3. Determine the protection level and explosion-proof type, explosion-proof level or anti-corrosion category and level of the explosion-proof motor according to the environment of use, as well as other requirements, such as outdoor and marine use.
1. The explosion-proof grade of the explosion-proof motor should meet the requirements of flammable and explosive environment, and the high grade should not be selected.
2. Determine the technical indicators of the explosion-proof motor according to the actual use. The higher the η, cosφ in the technical indicators, the better the motor control system and the more energy-saving. The other indicators are not so important. For example, for motors that drive axial-flow pumps and fans, Tst can be within the range of 0, 6 to 0, 8, and Tm does not need to be high. About 1.6 can meet the requirements. If the buyer looses a little bit on these two indicators, the designer can add the excess functions dug out from this to Ist, which is used to reduce Ist. This is of practical significance for occasions where the network capacity is small. The load of a two-pole motor is mostly fans and pumps. A Tst that is too high is not necessary. If the manufacturer pursues this index too much, designing the upper half of the cast aluminum rotor groove to be very narrow will add unnecessary difficulty to the manufacturing; there are also many failures caused by broken bars and thin bars during use.
3. You have to choose an explosion-proof motor with a moderate degree of protection. The difference between IP54 and IP44 is mainly reflected in the dustproof function. In order to save money, some buyers choose IP44 motors in places where IP54 should be used, so that the motor bearings will be damaged prematurely. On the contrary, when IP44 can meet the requirements of use, there is no need to choose IP54. The latter should be equipped with a rubber sealing ring, which is not as good as the former in terms of maintenance.