The vast majority of motors are not waterproof, largely because their working environment does not require waterproofing. Waterproofing materials increase costs and limit overall performance, which are usually only valuable for specific applications, such as pumps and fluid handling, off-road vehicles and other applications that can come into contact with liquids with motors. Due to water and solvent, motion control parts are often faced with the risk of corrosion and failure. Waterproof motor is the key component to solve the problem of water-induced motor failure. There is a standardized liquid protection measure in the motor industry, called IP protection level. Power engineering and motor manufacturers need to meet the requirements of application specifications.

The most common and effective waterproof method for motor

Today's waterproof motors can work 30 feet below the sea floor. This is a general industrial standard, named after "waterproof". It is not a modified standard motor, but a real waterproof motor. They can work well in deep water environment & mdash; & mdash; in various industrial and marine environments. The motors are equipped with redundant shaft seals, O-rings, sealed cable feedthrough lines, pressure equalizing and other waterproof features. These design features enable the motor to meet the needs of the design engineer for the motor. Even if the motor is exposed to or immersed in most liquids for a long time, the motor will not fail.

Each strategy provides different degrees of liquid protection when exploring waterproofing solutions. For example, in some special cases, only splash water is prevented, while in others the motor is completely submerged and to a certain depth. Many waterproof methods will limit the flow of air to the motor, which will have a negative impact on the maximum power output of the motor. The most common and effective waterproofing methods for motors are as follows:

1. Special enclosure: covering the motor with a special enclosure is one of the most common ways to prevent water damage. Special enclosure will be very expensive.

2. Waterproof shaft seal: protect the moving parts of the motor, especially the shaft and bearing. The waterproof shaft seal creates a closed area for the internal work of the motor.

Why can't ordinary motors meet this waterproof requirement?

Although standard motors are the backbone of industrial and laboratory motion control systems and provide reliable and accurate positioning at the lowest cost, their design has some weaknesses in terms of humidity. First, the coils of standard motors are wound with magnetic wires, which are solid copper wires coated with enamel or insulation. Although the coating process is good, it is not perfect, and there are always some small pinholes in the varnish. When the magnetic wire is wound into a coil, it is unlikely that any two pinholes will line up and & quot; short circuit & quot;.

In general, the wire spacing provided by the insulation prevents conduction from one pinhole to the next. If there is water between the windings, it also promotes pinhole to pinhole conduction. In this case, the current from the power supply can quickly damage the motor windings. High quality insulation and impregnation process can prevent this problem, but it greatly increases the product cost.

In humid environment, the materials of stator and rotor are easy to corrode and rust

The rotor and stator of the motor are mostly made of magnetic iron (silicon steel), which are easy to be corroded in humid environment. At the same time, in order to optimize the torque, the gap between the rotating teeth and non rotating teeth of the motor is kept at about 0.05mm. When the motor is running, these rotor slots become hot, usually high enough to turn any water in the motor into steam. The steam is corrosive, so the magnetic iron in the rotor teeth rusts faster than usual. Once the rust fills the 0.05mm air gap and the rotor and stator teeth start to rub, this will eliminate the effective torque of the motor and loosen the magnetic iron.

If rust is dry, it forms a matte powder, if it is wet, it forms a matte slurry. Once the oxide slurry enters the motor bearing, as abrasive, the bearing wear accelerates. With the bearing wear, the centering of the rotor becomes inaccurate, which causes the rotor to shake when rotating and finally hits the stator. The accumulation of oxide layer on the magnetic iron teeth and the loss of bearing accuracy will lead to motor failure in two weeks. Although non corrosive metals can be used instead of magnetic iron, this metal will be more expensive, the processing cost will be higher, and the motor performance will be significantly reduced.

The correct design of the motor is to try to prevent moisture from entering the motor

Standard motors are not designed for easy sealing, they are designed at a low cost. The correct sealing of waterproof motor requires a thorough redesign of the motor parts, thus increasing the manufacturing cost. The redesign includes shaft seals, O-rings, cable feedthrough lines and the pressure equalization mentioned earlier, as well as other combined features. For example, the standard motor enclosure is made of painted cold rolled steel and / or aluminum, while the exterior of a waterproof motor is usually made of non waterproof steelMade of stainless steel to prevent corrosion. The wiring to the motor coil requires a sealed feed through to prevent water from seeping into the motor through the cable conductor.

Other seal designs, such as the threaded pipe plug at the rear of the motor, are used to seal the housing after the motor connection is completed. The plug also needs to be equipped with an O-ring, and the motor shaft itself is equipped with redundant shaft seals. Additional features to extend service life include double insulation, coating lamination and pressurization fittings.

Source: today's motor