Electric Drive Bearing Leakage Current Testing Apparatus
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Solution Overview
Problem
Current methods for testing the service life of electric motor bearings are inadequate as they do not account for the impact of electrical leakage currents and require extensive, costly, and time-consuming full-scale tests to evaluate the influence of these currents on bearing durability, especially under varying loads and temperatures.
Innovation Solution
A device and method that simulate electrical and mechanical loads on bearings using adjustable voltage pulses, impedance adjustment, and force application to accelerate wear testing, allowing for reduced duration testing by monitoring vibrations, temperature, and electrical characteristics to determine service life thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically insulated bearings are used to cancel low frequency currents, then bearing protection against low frequency damage is improved, but high frequency currents continue to cross the bearings causing deterioration
Solution Approach 1:
The patent applies different insulation characteristics to different frequency ranges. The bearing insulation is designed with specific electrical properties that selectively block low frequency currents while allowing high frequency currents to pass through, addressing the local quality of electrical resistance at different frequencies.
Solution Approach 2:
The patent changes the electrical parameters of the bearing insulation to create frequency-dependent behavior. By adjusting the insulation's capacitive and resistive characteristics, the bearing can differentiate between low frequency and high frequency currents, blocking one while permitting the other.
2Measurement precision
If full-scale motor tests are conducted to evaluate bearing service life, then comprehensive bearing performance data is obtained, but test equipment requirements and test duration increase significantly
Solution Approach 1:
The patent extracts the bearing from the complete motor system and tests it independently on a simplified test bench. This extraction allows testing of bearing-specific parameters without requiring the complex full-scale motor test equipment, while still obtaining comprehensive bearing performance data.
Solution Approach 2:
The patent segments the testing process into separate components: electrical stress application, mechanical load application, and performance monitoring. This segmentation allows each aspect to be tested independently with specialized equipment rather than requiring a complete motor test system.
3Measurement precision
If full-scale motor tests are conducted to evaluate bearing service life, then comprehensive bearing performance data is obtained, but test time requirements increase significantly
Solution Approach 1:
The patent applies preliminary electrical stress to the bearing insulation before mechanical testing begins. By pre-conditioning the insulation with controlled electrical pulses, the bearing reaches its failure state faster, reducing the total test duration while maintaining evaluation accuracy.
Solution Approach 2:
The patent uses periodic electrical pulse application during testing to accelerate insulation degradation. The repeated cycling of electrical stress creates cumulative damage more rapidly than continuous operation, thereby reducing the time required to evaluate bearing service life.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient evaluation of bearing service life under simulated electrical leakage conditions, reducing testing time and accounting for mechanical and electrical stresses, thus providing a more comprehensive assessment of bearing endurance.
Implementation Method 1
When the motors are supplied by inverters, the leakage currents have much higher frequencies which can reach 100kHz, or even a few MHz
Implementation Method 2
electrically insulated bearings can be used which completely cancel the passage of currents at low frequency. But these insulations have a capacitive behavior so that the high frequency currents continue to cross the bearings
Implementation Method 3
the subject matter of the invention is a device (1) comprising at least one vibration measuring means (13) arranged on the bearing (2) intended to receive a bearing (3)
Implementation Method 4
at least one temperature measuring means (14) arranged on the bearing (2) intended to receive a bearing (3)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The device has bearings (2, 4) for receiving rollers (3, 5) to be tested, respectively, and a rotational driving shaft (6) for driving the rollers. The shaft is engaged with a rotational driving motor (9). An electric impulse generator (11) generates impulses of electric current flowing between the bearings and the shaft passing through the rollers. Acceleration measuring units (13, 15) measure intensity of vibration of the rollers. Temperature measuring units (14, 16) determine operating temperature conditions of the rollers. The units are arranged on the bearings. An independent claim is also included for a method for testing influence of leakage electric current on life duration of rollers for an electric motor.