7 types of special test for explosion-proof motor

Shell strength test

The strength and sealing of the motor and the attached pipe are checked with air or inert gas. The strength of the shell should be able to withstand the 1.5~2 times of the maximum overvoltage specified in the normal work, but the minimum is 200Pa, the test time is 1min, and the outer shell, pipe and seal ring are not damaged.


FLF spray test

The inlet and outlet of motor ventilation ducts should be located in a safe place without explosion hazard. If the exhaust port is located in the explosion danger place, the exhaust vent should be equipped with fireproof flower, electric arc and combustible material blown out of the shell. If the clearance between the rotating shaft and the joints at each joint of the pipe may have the danger of ejecting sparks, sparks can be made artificially, such as igniting some combustible material, and then normally ventilating, and observing whether the spark can blow out of the gap.


Minimum wind pressure test

According to the design requirements, connect the fan and ventilation channel, and adjust the air pressure and air volume at the intake port. The measurement points of wind pressure are determined according to the motor structure, the air flow path and the size of the wind path. The pressure measuring points should be set at low wind pressure and where the explosive gas may enter the gap of the shell, generally located in the following positions: (1) inlet and outlet. (2) where the pressure meter is to be installed. (3) where the shell may leak, such as the shaft extension. (4) the place where the air flow has changed dramatically.

Generally, the U pressure gauge, micro pressure gauge and pitot tube are used to measure wind pressure. The flow and pressure values of the intake port are adjusted. When the technical conditions are met, the positive pressure value of each measuring point is measured to exceed 50Pa. The test should be carried out at motor static and rated speed respectively.


Test of ventilation dead angle test

The motor shell is filled with hydrogen (nitrogen or carbon dioxide), and its concentration is 60% + 1%. Ventilation and washing are carried out with the air volume of 5 times the total volume of the motor shell and the auxiliary pipe or the volume and time stipulated in the product specification. Then, the gas analyzer is used to measure 3-5 places of the expected ventilation angle. The above gas concentration is less than 1%.


Reliability test of interlocking device between motor and fan

Positive Motors should be ventilated and cleaned before working. The working system of the ventilator should ensure that the motor can not be connected to the power supply before the motor and the wind pipe is ventilated. Only when the air in the motor and the wind pipe is quantified (at least 5 times the volume of the motor and the air tube cavity) can the motor be connected to the power supply. When the motor is stopped, the ventilator can stop ventilation only when the surface temperature of the internal parts of the motor is lower than the superheated temperature permitted by the explosive gas. The test is the test to ensure the accuracy and reliability of the above control system.


Action reliability test of wind pressure protection device

The positive pressure motor must maintain the wind pressure specified in the product during normal operation. When artificially lowering the wind pressure at the outlet to the minimum wind pressure specified in the 100Pa or the product, the wind pressure protection device should act.

This is to be carried out for 5 times. If the pressure relay can not be installed at the outlet of the air outlet, in order to check and supervise the wind pressure at the air outlet, the action value of the pressure relay is often increased to ensure the wind pressure of the outlet of the motor. This test should be repeated in addition to the motor when it is out of factory, and during the commissioning of the installation site.


Test on cooling time of motor housing temperature rise and internal heating element after power failure

The surface of positive pressure motor housing and internal heating element must be measured at the rated load of motor. The wind pressure and air volume are measured at the minimum flow and pressure. The maximum temperature of the motor housing is also necessary to measure when the wind stops. To use the stopwatch to heat the part inside the shell to determine the time required to cool the surface temperature to the limit temperature after cutting off the power supply, that is, the maximum surface temperature of the device. This time is the shortest time that the motor will continue to be ventilated when the motor is terminated.