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The Ultimate Guide to Insulated Motor Bearings
With the popularity of industrial automation and electric equipment, motors are increasingly used in various industrial applications. However, during the operation of the motor, the bearings are often damaged due to the influence of current. This damage not only affects the normal operation of the equipment, but also increases maintenance costs. Therefore, insulated motor bearings have received widespread attention as an effective solution. This article will delve into the relevant knowledge of motor insulated bearings, including their definition, working principle, advantages and disadvantages, grades, insulation inspection, selection criteria, etc., and introduce a professional motor insulated bearing manufacturer – Aubearing, aiming to provide technical personnel and Engineers provide comprehensive references.
Insulated motor bearings refer to bearings that have electrical insulation properties and can block the passage of current. Insulated motor bearings are special bearings that prevent the flow of electricity through the bearing itself. Its insulation performance is usually achieved by coating the inner or outer ring of the bearing with a layer of insulating material, or using ceramic rolling elements. These materials include aluminum oxide coatings and silicon nitride ceramics, plastics, rubber, etc., which have excellent insulation properties. These materials offer excellent insulating properties and resistance to wear and tear. Common types of insulated bearings include outer ring insulated bearings (code VL0241) and inner ring insulated bearings (code VL2071).
The surface of the insulating bearing is coated with a high-quality film that has strong bonding force with the substrate and has excellent insulation performance. After continuous improvement, this process can form a layer of coating with uniform thickness and strong adhesion on the outer or inner ring surface of the bearing, with a thickness of up to 100 μm. The insulated bearing can withstand voltages up to 1000 V DC. .
Advantages of insulated motor bearings
Improve equipment reliability
Insulated motor bearings can effectively isolate current and avoid the impact of current on the bearings, thereby protecting the safe operation of the equipment and improving the reliability of the equipment.
Extend equipment life
Insulated motor bearings are made of special materials and manufacturing processes and have excellent high temperature resistance and corrosion resistance. They can operate normally in harsh environments, thereby extending the service life of the equipment.
Reduce maintenance costs
Using insulated motor bearings reduces maintenance costs by reducing equipment breakdowns and repairs. In addition, insulated bearings can also reduce the deterioration of grease and extend the lubrication cycle.
Economy
Although the initial cost of insulated motor bearings is higher, its advantages in improving equipment reliability, extending service life and reducing maintenance costs make it economical overall.
Grades of insulated motor bearings
The insulation grades of insulated motor bearings mainly include three categories:
General insulation
Suitable for ordinary equipment and environments, the insulation resistance is greater than 50MΩ. This grade of insulated bearings is mainly used in low-voltage motors and general industrial equipment, and can meet general insulation requirements.
High resistance insulation
Suitable for equipment and environments with high requirements, such as humidity, high temperature, high voltage, etc., with insulation resistance greater than 500MΩ. This grade of insulated bearings is usually used in high-voltage motors and equipment in harsh environments and has higher insulation properties.
Ultra high resistance insulation
Suitable for special environments, such as chemical industry, nuclear power, etc., with insulation resistance greater than 1000MΩ. This grade of insulated bearing has the highest insulation performance and can provide reliable electrical isolation in extreme environments.
According to the different insulation parts and materials, insulated motor bearings can be divided into the following categories:
Insulated outer ring bearings: The outer ring surface of the bearing is coated with insulating material and is suitable for most motor applications.
Inner ring insulated bearings: The inner ring surface of the bearing is coated with insulating material, suitable for specific motor designs.
Hybrid insulated bearings: Designed with a combination of ceramic rolling elements and insulating coating, providing higher insulation performance and wear resistance.
Full-ceramic insulated bearings: Bearings made of all-ceramic materials have extremely high insulation performance and wear resistance, and are suitable for extreme environments.
Insulation performance testing of insulated motor bearings
The insulation performance of insulated motor bearings is an important factor in ensuring reliable operation of the motor. Insulation inspection is a key step to evaluate the quality and performance of insulated bearings, which can effectively prevent electrical corrosion and extend the service life of the motor. Next, the insulation inspection methods, steps and importance of insulated motor bearings will be introduced in detail, and analyzed and explained through actual data.
Insulation resistance measurement
Insulation resistance measurement is the basic method to evaluate the insulation performance of insulated bearings. This is usually measured using an insulation resistance meter (megohmmeter). The measurement steps are as follows:
1. Preparation: Remove the bearing from the motor and clean the bearing surface to ensure that no contaminants will affect the measurement results.
2. Connect the instrument: Connect the E end of the insulation resistance meter to the rotating shaft, and connect the L end to the insulating part of the bearing (such as the outer ring). You can use aluminum foil to wrap the outer ring and secure it with bare copper wire, and then connect it to the L terminal.
3. Measure the insulation resistance: Start the insulation resistance meter and record the reading. For general applications, the insulation resistance should be greater than 50MΩ; for high-demand situations, the insulation resistance should be greater than 500MΩ; in special environments, the insulation resistance should be greater than 1000MΩ.
According to actual data, the insulation resistance of some high-voltage motors’ insulated bearings can reach than 1000 MΩ, which is significantly higher than the insulation requirements of ordinary motors.
Shaft voltage measurement
The purpose of shaft voltage measurement is to understand the magnitude of the shaft current when the motor is running. The shaft voltage is caused by the magnetic asymmetry between the motor rotor and stator, and its magnitude directly affects the shaft current. The measurement steps are as follows:
1. Preparation: Make sure the motor is in normal operation and connect the voltage measuring instrument.
2. Connect the measuring instrument: Connect one end of the voltmeter to the non-driving end of the motor shaft, and the other end to ground.
3. Measure the shaft voltage: Start the motor and record the shaft voltage value. Normally, the shaft voltage should be kept in a low range (such as tens of millivolts) to prevent excessive shaft current.
Actual measurement data shows that the shaft voltage of some high-power variable frequency motors is between 50mV and 200mV. These voltage levels will generate significant currents in the bearings, so insulated bearings are required to block these currents.
Shaft current measurement
Shaft current is the current flowing through the bearing, which directly affects the insulation performance and service life of the bearing. The measurement steps are as follows:
1. Preparation: Make sure the motor is in normal operation and connect the current measuring instrument.
2. Install an insulation device: Install an insulation ring between the bearing at the non-driving end of the motor and the casing to ensure good insulation of the motor bearing.
3. Connect the measuring instrument: Connect the ammeter in series to the metal piece in contact with both sides of the bearing insulation layer.
4. Measure the shaft current: Start the motor and record the shaft current value. Under normal circumstances, the shaft current should be as close to zero as possible to prevent current flow through the bearings.
According to actual data, the measured shaft current of some high-voltage motors is between 0.1A and 0.5A. Although these current values may seem small, long-term operation can cause significant galvanic corrosion of the bearings, which must be protected by insulating the bearings.
Experimental data support
In order to further illustrate the importance and effect of insulation inspection, Aubearing cited some actual data for analysis. In a test of 200 high-voltage motors, it was found that the average insulation resistance of motors with insulated bearings after 1,000 hours of operation was 800 MΩ, while the average insulation resistance of motors without insulated bearings was 200 MΩ. In addition, the measurement data of the shaft current shows that the insulated bearing can reduce the shaft current from 0.3A to 0.05A, effectively protecting the insulation performance of the bearing. These data show that regular insulation inspections and corresponding protective measures, such as the use of insulated bearings, can significantly improve the operating reliability of the motor, extend its service life, and reduce maintenance costs.
Choosing the right insulated motor bearings
Consider environmental conditions
When selecting insulated motor bearings, it is necessary to fully consider the environmental conditions in which the equipment operates, such as temperature, humidity, chemical corrosion, etc. These conditions will directly affect the performance and life of insulated bearings.
Evaluate load and speed
The selection of insulated motor bearings also needs to be determined based on the load and operating speed of the equipment. Different loads and speeds require different types of insulated bearings to ensure that they can meet the operating requirements of the equipment.
Consider insulation levels
Select the appropriate insulation level based on the electrical requirements of the device. Generally speaking, high-voltage motors and equipment in special environments need to choose high-resistance or ultra-high-resistance insulated bearings to provide better electrical isolation performance.
Focus on manufacturing processes
The manufacturing process of insulated motor bearings has an important impact on their performance. Choosing an insulated bearing supplier with advanced heat treatment manufacturing processes and quality control can ensure the insulation performance and service life of the bearing.
Cost-benefit analysis
Although the initial cost of insulated motor bearings is higher, its advantages in improving equipment reliability, extending service life and reducing maintenance costs make it economical overall. When choosing insulated bearings, you need to consider their cost-effectiveness.
Conclusion
As an effective solution, insulated motor bearings play an important role in preventing current from passing through the bearings and protecting the safe operation of equipment. Although its initial cost is higher, its advantages in improving equipment reliability, extending service life and reducing maintenance costs make it very widespread in motor applications. When selecting and using insulated bearings, factors such as motor type, operating voltage, and environmental conditions need to be comprehensively considered to ensure the best results. As a professional insulated motor bearing manufacturer and supplier, Aubearing is committed to providing high-quality insulated bearing products to meet the various needs of customers.
FAQ
How long is the service life of insulated bearings?
The service life of insulated bearings depends on their application environment and maintenance conditions. Under normal circumstances, their service life can be extended by than 50% than ordinary bearings.
Do insulated bearings require special installation methods?
The installation method of insulated bearings is similar to that of ordinary bearings, but special attention must be paid to the integrity of the insulation layer to avoid damage to the insulation layer during installation.
Are insulated bearings expensive to maintain?
The maintenance cost of insulated bearings is slightly higher than that of ordinary bearings, but it can significantly reduce the overall maintenance cost and downtime of the motor, so it is a cost-effective choice in the long run.
What types of insulated bearings does Aubearing offer?
Aubearing provides various types of insulated bearings, including deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings, etc., to meet the needs of different motor equipment.