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What factors should be considered in the selection of imported explosion-proof motors?

In the selection of explosion-proof motors, it is necessary to carefully consider some factors and several aspects that need attention, so that there will be no errors in the selection, and it can ensure the normal and safe operation after the machine is purchased. So, what factors should be considered when choosing an explosion-proof motor?
There are three main factors to consider when choosing an explosion-proof motor.
1. After the voltage, frequency and speed are determined, according to the load of the motor and the condition of the power supply network, the installation coefficient K is selected to determine the motor power. The mounting dimensions are determined from the motor samples by installation. There are also cases where 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 the wound rotor motor, in order to select the matching start and speed control system, the supplier also needs to provide the values of the rotor voltage U2 and the current I2.
3, according to the use of the environment to determine the degree of protection and explosion-proof type, explosion-proof grade or corrosion-resistant categories, grades, and other requirements, such as outdoor, marine and so on. Reference: Explosion-proof motor temperature group and explosion-proof category.

Pay attention to the following three points when using an explosion-proof motor
1. The explosion-proof grade of the explosion-proof motor can meet the requirements of flammable and explosive environment. 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, save energy, and the rest of the indicators are not entirely. For example, drag the axial flow pump and the fan motor, Tst can be in the range of 0.6~0.8, Tm does not have to be high, about 1.6 can meet the use requirements. If the buyer looses a little on these two indicators, the designer can patch the excess function from this to Ist, which is used to reduce Ist. This is very practical for a place with a small network capacity. Most of the load on the two-pole motor is a fan and a pump, and Tst is not necessary. If the manufacturer is too eager to pursue this index, the upper half of the cast aluminum rotor trough shape is designed to be narrow, which makes it unnecessary to manufacture; in the use, there are many faults caused by broken strips and thin strips.
3, the degree of protection should be selected moderately. The difference between IP54 and IP44 is mainly in the dustproof function. In order to save money, some buyers choose IP44 motors in the IP54 location to make the motor bearings prematurely damaged. Conversely, when IP44 can meet the usage requirements, it is not necessary to select P54. The latter should be equipped with a rubber seal, which is not as good as the former.

Explosion-proof motor type
Explosion-proof motor protection level is at least IP55, while ordinary motors have IPIP23, IP44, IP54, IP55, IP56, so it can be distinguished from the shape.
Explosion-proof motors can be divided according to product type
1, according to the principle of the motor
Can be divided into explosion-proof asynchronous motor, explosion-proof synchronous motor and explosion-proof DC motor.
2, according to the place of use
It can be divided into explosion-proof motors for underground coal mines and explosion-proof motors for factories.
3, can be divided into explosion-proof motor, increased safety motor, positive pressure motor, non-sparking motor and dust explosion-proof motor, etc.
4, according to the matching host points
It can be divided into explosion-proof motor for coal mine transport machine, explosion-proof motor for coal mine winch, explosion-proof motor for rock loader, explosion-proof motor for coal mine partial fan, explosion-proof motor for valve, explosion-proof motor for fan, marine explosion-proof motor, explosion-proof motor for lifting metallurgy And the hydrogenation device is equipped with an increased safety type brushless excitation synchronous motor. In addition, it can also be divided according to technical indexes such as rated voltage and efficiency, such as high-voltage explosion-proof motor, high-efficiency explosion-proof motor, high slip rate explosion-proof motor and high starting torque explosion-proof motor.
According to product series and its characteristics
1, flameproof motor
It uses an explosion-proof enclosure to separate electrical parts that may generate sparks, arcs, and hazardous temperatures from the surrounding gas mixture. However, the outer casing is not sealed, and the surrounding gas mixture can enter the interior of the motor through the joint gap of the various parts of the outer casing. It may occur when it comes into contact with the ignition source such as sparks, arcs, or dangerous high temperatures in the casing. At this time, the flameproof casing of the motor will not be damaged or deformed, and when the flame or hot gas passes through the joint gap, it cannot Ignite the surrounding gas mixture.
The main features of explosion-proof motors are:
(1) The correspondence between power class, installation size and speed is consistent with DIN42673. Considering the compatibility with the YB series and the interchangeability of the Y2 series, necessary adjustments are made, which are more effective and applicable.
(2) The noise limit is lower than that of the YB series, which is close to the Y-class noise of the YB series, and the vibration limit is equivalent to the YB series.
(3) The whole series adopts Class F insulation, and the temperature rise is assessed according to Class B.
(4) There are two types of motor heat sinks: parallel horizontal distribution and radiation distribution, which are mainly parallel horizontal distribution.
(5) The whole series uses low-noise deep groove ball bearings, and the center of the machine base is higher than 180mm.
(6) The enclosure protection level is increased to IP55.
(7) The main performance indicators reached the international advanced level in the early 1990s.
2, increased safety motor
It is a motor structure that does not generate arcing, sparking or dangerous high temperatures under normal operating conditions, and then takes some mechanical, electrical and thermal protection measures to further avoid arcing, sparking or under normal or approved overload conditions. The danger of high temperatures ensures the safety of explosion protection.
The characteristics of the increased safety motor are:
(1) To meet the requirements of increased safety explosion-proof motors, a series of reliable measures to prevent sparks, arcs and dangerous high temperatures can be safely operated in hazardous areas in Zone 2.
(2) Adopting brushless excitation, setting the rotating rectifying plate and static excitation cabinet, the excitation control system is reliable; the ac-polarity is poorly excited and has no impact; the excitation system is out of step protection and reliable, and the whole step ability is strong; the circuit design is reasonable The discharge resistor does not generate heat during operation; the excitation current adjustment range is wide.
(3) Synchronous machine, AC exciter and rotating rectifier are coaxial. The rectifier disk is located between the main motor and the exciter or outside the housing.
(4) The enclosure is rated IP54.
(5) Class F insulation is used, and the temperature rise is assessed according to Class B.
(6) Change the traditional water cooling to the upper water cooling, that is, the water cooler is placed on the upper part of the motor.
(7) Set the increased safety type moisture-proof heater, which is fixed in the cover at the bottom of the motor and used for heating and moisture-proof when the machine is stopped.
(8) Select high-quality raw materials, and leave a large margin for electrical and mechanical calculations to meet the operational reliability and temperature requirements of increased safety motors.
(9) There are perfect monitoring measures; the increased safety-type self-balancing current transformer for differential protection is installed in the main junction box; the stator winding is buried and the standby platinum thermal resistance is set, the graduation number is Pt100; The instrument monitors the leakage of the water cooler; the sliding bearing at both ends is provided with an on-site temperature display instrument and a remote signal terminal.
3. Positive pressure motor
A positive pressure type motor is a type of positive pressure type electrical equipment.
The structure of the positive pressure motor is
(1) There is a complete ventilation system, and there is no structural dead angle inside the motor that may affect the ventilation.
(2) The outer casing and piping are made of non-combustible material and have sufficient mechanical strength.
(3) The casing and the main pipe maintain a sufficiently large positive pressure relative to the outside atmosphere.
(4) The motor must have safety protection devices (such as time relay and flow monitor) to ensure sufficient air exchange, and must also have automatic protection or alarm device for air pressure undervoltage in the casing.
(5) The quick opening door or cover on the outer casing shall have means for interlocking with the power supply. There is no unified series of positive pressure motors in China.
Standard for explosion-proof motors
The rated voltage, rated current, power and speed of the explosion-proof motor are the same as those marked by the ordinary motor. The explosion-proof motor has more explosion-proof marks: Ex, explosion-proof type + equipment category + (gas group) + temperature group explosion-proof type.
The standard of explosion-proof motor is jointly issued by the General Administration of Quality Supervision, Inspection and Quarantine and the China National Standardization Administration Committee for the "energy efficiency limit value and energy efficiency rating of small and medium-sized three-phase asynchronous motor". In the industry of anti-riot motor, the basic series of explosion-proof motors must follow this standard.
1. The explosion-proof motor industry must resolutely implement the “energy-saving limit value and energy efficiency rating of small and medium-sized three-phase asynchronous motor” explosion-proof motor standard, which can achieve energy conservation and emission reduction targets in China, and make great contributions to environmental protection. The license will also be issued in accordance with the new standards of the explosion-proof motor industry;
2. Although the energy efficiency value in the national standard GB18613-2012 has been improved compared with the previous version, the specifications of the YB3 series flameproof three-phase asynchronous motor currently promoted in this industry in China are all satisfied with 3 in GB18613-2012. The energy efficiency limit value of the class, and some specifications can reach the new standard level 2 target energy efficiency limit value.
3. Please accelerate the production and marketing speed of YB3 series motor manufacturers. At that time, the relevant departments of the National Explosion-proof Electrical Products Quality Supervision and Inspection Center and the Explosion-proof Electrical Products Production License Examination Department will assist enterprises to do this work.
4. Since September 1, 2012, the small and medium-sized three-phase asynchronous motors that are manufactured or imported by various production enterprises or importers shall be in accordance with the national standard GB 18613-2012, the energy efficiency limit value and energy efficiency rating of small and medium-sized three-phase asynchronous motors. 》Add energy efficiency label. The Energy Efficiency Labeling Management Center of the China National Institute of Standardization has now begun to accept filings in accordance with the new standards. Our company has filed for it. The segmentation of the new record is the same as before, but the test method is modified from the original miscellaneous consumption according to the method of 0.5% to the loss analysis method of the input-output power according to the B method in GB/T 1032. For models that have been previously filed according to the 2006 version of the standard, a change record is required, and one test report is required for the change record.
5, when the explosion-proof motor is purchased, it depends on whether the production is equipped with an explosion-proof certificate. Explosion-proof motors are mainly used in coal, oil and gas, petrochemical and chemical industries. The rated voltage, rated current, power and speed of the explosion-proof motor are the same as those marked by ordinary motors, which means that the explosion-proof motor has more explosion-proof.
6, mark: Ex one, explosion-proof type + equipment category + gas group + temperature group explosion-proof type.

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