Selection of explosion-proof motor
There are three main factors to consider when choosing an explosion-proof motor:
1. After the voltage, frequency, and rotation speed are determined, according to the load dragged by the motor and the power supply network condition, the installation coefficient K is selected to determine the motor power. Check the installation dimensions from the motor catalog by the installation method. In some cases, the motor power is selected from the sample from the determined center height.
2. Confirm whether the technical indicators meet the requirements (the supply and demand sides are finalized in the technical agreement). For a wound rotor motor, in order to select a matching starting and speed regulation system, the supplier must also 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 according to the use environment, and other requirements, such as outdoor and marine use. See also: Explosion-proof motor temperature group and explosion-proof category.
Pay attention to the following three points when selecting explosion-proof motors
1. The flameproof level of the flameproof motor can meet the requirements of flammable and explosive environments. Do not choose a high level.
2. Determine the technical indicators according to the actual use situation. The higher the η and cos φ in the technical indicators, the better, to save power, and the rest of the indicators are not necessarily the same. For example, the motor for dragging the axial flow pump and fan can be within the range of 0.6 ~ 0.8, and Tm does not need to be high, and about 1.6 can meet the use requirements. If the buyer looses a little on these two indicators, the designer can apply the excess function dug out from this to Ist, which is used to reduce Ist. This is of practical significance for places with small network capacity. The load of the two-pole motor is mostly fans and pumps, and Tst is not necessary. If the manufacturing plant is pursuing this index too much, the upper half of the cast aluminum rotor groove shape is designed to be very narrow, which adds unnecessary difficulty to manufacturing; there are also many failures caused by broken bars and thin bars in use.
3, the protection level should be selected appropriately. The difference between IP54 and IP44 is mainly in the dustproof function. In order to save money, some buyers choose an IP44 motor in the place where the IP54 is used, so that the motor bearings are damaged prematurely. Conversely, when IP44 can meet the requirements of use, there is no need to choose P54. The latter should be equipped with rubber seals, which is inferior to the former in maintenance.