Medical centrifuge stop does not turn or slow speed failure analysis

Medical centrifuges are commonly used to separate serum, plasma, precipitate proteins or to check for urine sediment. The medical centrifuge can quickly precipitate the suspended particles in the mixed liquid, thereby separating various components of different specific gravity. In actual work, due to the relatively concentrated use time of the medical centrifuge opening and stopping, the motor and the machine are worn and consumed greatly. If the maintenance work cannot be done regularly on time, it is easy to cause the failure of the stop or the slow speed, which directly affects the failure. The normal operation of the inspection work. The following is a detailed analysis of the failure of the medical centrifuge to stop or slow down:

When the medical centrifuge has a failure to stop or rotate slowly, the first part of the power supply must be eliminated. If the power cord is disconnected, the plug and socket are in poor contact, the bearing is damaged, or the stator or rotor coil is short-circuited or broken, and burned. Secondly, due to the open circuit of the brush, that is, the commutator on the rotor does not match the brush and the contact is poor. Because the motors used in medical centrifuges are generally series motors. It consists of two parts, the stator and the rotor. The stator is a concentrated fixed magnetic pole composed of a core and a field coil. The rotor is composed of a core and a rotor coil and a commutator. The function of the brush is to connect the stator coil to the key components of the rotor coil via the commutator. The circuit working principle of the series-excited motor is that the current flows from the power source through the stator field coil, the brush, and the commutator into the rotor coil, and then the brush and the stator field coil return to the power source to form a loop. The field coil and the rotor coil are connected in series by a commutator. The currents in the lines are equal, so only if the series circuit is unobstructed, the motor can work normally at the required speed. It can be seen that the working condition of the brush directly affects the normal operation of the motor. However, due to the contact between the brush and the commutator, wear, consumption or spring failure, the brush open circuit and the commutator are easily disengaged. It is the main cause of the centrifuge shutdown or slow speed failure.

The solution is to clean the medical centrifugal electromechanical brush box and check the brush wear. When the length of the brush is less than 10mm, replace the brush of the same specification. To replace the brush, unscrew the brush cover and remove the old brush. If the spring on the old brush is intact, remove it and reattach it to the new one. If the spring fails or is damaged, the spring should be replaced at the same time, and then the positive direction should be put back into the box as it is, so that the brush can freely fall in the box, and the tightness is appropriate, and then the lid is tightened. Remove the turntable, adjust the motor speed to the maximum, let the motor run at no load, then the speed will be very high, and the end face of the brush will match the outer edge of the commutator after a few minutes. At this time, the machine can be shut down, the motor is disassembled, the oxide on the surface of the commutator is removed by fine sandpaper, and the carbon powder particles on the commutator are removed by a brush or a dry cloth. Finally, you can restore the machine.

In order to ensure the normal operation of the centrifuge, preventive maintenance work should be done carefully. The wear of the commutator and the brush should be checked regularly (half or one year). Eliminate carbon contamination on the surface of the commutator in a timely manner and prolong the service life of the brush. For damaged devices, such as brushes, springs, etc., be replaced in time to ensure that the centrifuge is in good working condition.