Current Diverter Ring Conducts Shaft Voltage to Ground
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods fail to effectively and efficiently ground shaft voltage in rotating equipment, leading to premature bearing failure due to electrostatic discharge machining, as they either add complexity and cost or do not address the issue of impedance paths for current flow.
Innovation Solution
A current diverter ring is introduced that conducts and directs accumulated bearing current to ground, utilizing conductive segments within the ring, preferably made of materials like bronze, to create an effective low-impedance path for electrical charge dissipation, thereby preventing electrostatic discharge through the bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shaft sealing devices (lip seals, magnetic seals) are used to protect bearing environment, then sealing effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the sealing function from complex mechanical seals and replaces it with a simple labyrinthine structure formed by rotor and stator surfaces. This labyrinth seal uses geometric complexity rather than component complexity to achieve sealing, eliminating the need for lip seals, magnetic seals, or other sophisticated sealing devices while maintaining bearing protection.
2Productivity
If VFD controlled motors are used to regulate speed, then productivity is improved, but bearing current damage occurs due to parasitic capacitance
Solution Approach 1:
The patent introduces conductive segments as an intermediary element between the rotor shaft and bearing. These segments provide a preferred electrical path that intercepts bearing current before it reaches the bearing, acting as a mediator that redirects the harmful current flow away from the bearing while allowing the VFD system to continue operating.
3Reliability
If shaft voltage accumulates on rotor until discharge threshold is exceeded, then electrostatic charge builds up, but bearing damage occurs through EDM effect
Solution Approach 1:
The patent implements preliminary action by providing continuous electrical discharge paths through conductive segments before shaft voltage can accumulate to dangerous levels. The segments are positioned to intercept and continuously dissipate electrostatic charge, preventing the voltage buildup that would lead to EDM discharges through the bearing, thereby protecting bearing integrity proactively rather than reactively.
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
The current diverter ring significantly reduces shaft voltage and electrostatic discharge, extending bearing life by ensuring efficient electrical charge dissipation directly to the motor housing, rather than through the bearings, thus preventing premature failure.
Implementation Method 1
At least one conductive segment is positioned within the stator such that the conductive segment is in contact with the rotor shaft so as to direct accumulated bearing current to ground.
Implementation Method 2
Adequate maintenance of rotating equipment, particularly electric motors, is difficult to obtain because of extreme equipment duty cycles, the lessening of service factors, design, and the lack of spare rotating equipment in most processing plants.
Data Source
AI summary
The current diverter rings and bearing isolators serve to dissipate an electrical charge from a rotating piece of equipment to ground, such as from a motor shaft to a motor housing. One embodiment of the current diverter ring includes an inner body and an outer body configured to clamp at least one conductive segment between them. In the preferred embodiments of the current diverter ring, the conductive segments are positioned in radial channels. The outer body may be affixed to a shaft, a motor housing, a bearing isolator, or other structure. The bearing isolator may incorporate a retention chamber for holding conductive segments within the stator of the bearing isolator, or the bearing isolator may be fashioned with a receptor groove into which a current diverter ring may be mounted.