Grounded Diode Pack for Static Charge Dissipation
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Solution Overview
Problem
Generators, particularly integrated drive generators, experience rectifier assembly failures due to damaging electrostatic discharges between the rotor frame and isolated rotor circuits, which exceed diode voltage ratings, leading to diode breakdown and shorts.
Innovation Solution
A diode pack design that incorporates an oil transfer tube bushing with a conductive coupling to a DC rail or rotor shaft, providing a path for non-damaging dissipation of static charges, preventing the buildup of high voltages that could cause damaging discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor circuit is electrically insulated from the rotor frame, then the rotor circuit can be isolated for electrical safety, but static charge accumulates and causes damaging discharges that exceed diode voltage ratings
Solution Approach 1:
A resistive element is introduced as an intermediary between the rotor circuit and rotor frame. This resistor provides a controlled path for static charge dissipation, preventing dangerous voltage accumulation while maintaining electrical isolation for safety. The resistive mediator balances both requirements by allowing controlled charge leakage without creating direct electrical connection.
Solution Approach 2:
The electrical properties of the rotor circuit interface are changed by introducing a specific resistance value. Instead of complete insulation (infinite resistance) or direct connection (zero resistance), a intermediate resistance value is selected to control the discharge rate of static charge, transforming the electrical parameter to achieve both safety and discharge prevention.
2Object-affected harmful factors
If a grounding connection is provided from the rotor circuit to the rotor shaft, then static charge can be dissipated, but the electrical isolation and safety are compromised
Solution Approach 1:
A resistive element serves as an intermediary component between the rotor circuit and rotor frame, providing controlled charge dissipation while maintaining electrical isolation. The resistor acts as a mediator that allows static charge to leak off safely without creating a direct conductive path that would compromise electrical safety.
Solution Approach 2:
Instead of providing direct grounding (low resistance) to dissipate static charge, the invention inverts the approach by using high resistance to control the dissipation rate. The resistive path allows charge to leak off slowly and safely, preventing both accumulation and dangerous discharge, while maintaining electrical isolation.
3Temperature
If oil is used to cool the diode pack, then thermal management is improved, but the oil can become charged and cause static discharge damage
Solution Approach 1:
The oil transfer tube bushing is made conductive and connected to the rotor frame, creating an equipotential path for the oil. By equalizing the electrical potential of the oil with the rotor frame, the invention prevents charge accumulation on the oil, eliminating the hazard of charged oil discharge while maintaining the cooling function.
Solution Approach 2:
The conductive oil transfer tube bushing acts as an intermediary that provides a charge dissipation path for the cooling oil. The bushing mediates between the oil and the rotor frame, allowing any charge on the oil to be safely transferred to the frame, preventing discharge damage to the diode pack.
4Reliability
If the oil transfer tube bushing is electrically insulated, then electrical isolation is maintained, but the oil can accumulate static charge and cause damaging discharges
Solution Approach 1:
The oil transfer tube bushing is made conductive and connected to the rotor frame, creating an equipotential condition for the oil. This ensures the oil remains at the same electrical potential as the frame, preventing charge accumulation and discharge, while the bushing itself maintains the structural isolation function.
Solution Approach 2:
The electrical property of the oil transfer tube bushing is changed from insulating to conductive. This parameter change allows the bushing to serve dual functions: maintaining structural isolation while providing a charge dissipation path for the oil, preventing static charge accumulation.
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 design effectively prevents static charge accumulation and resulting discharges, thereby protecting diodes from damage and ensuring reliable generator operation by maintaining the rotor circuit and oil in a fixed potential relative to the rotor shaft, preventing reverse bias and electrical arcs.
Implementation Method 1
an oil transfer tube bushing with a conductive coupling to a DC rail or rotor shaft, providing a path for non-damaging dissipation of static charges
Implementation Method 2
preventing the buildup of high voltages that could cause damaging discharges
Data Source
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AI summary
The present disclosure relates to generators and their components. A design to accommodate non-damaging dissipation static charge build-up is disclosed. Non-damaging dissipation of accumulated charge involves the provision of a suitable electrical path that will allow charges to flow to ground. A grounded diode pack 10 is disclosed, having an electrically conductive oil transfer tube bushing 115 electrically coupled to a DC rail 60, 65. A method of preventing damaging static discharge of a diode pack 10 comprises coupling an electrically conductive oil transfer tube bushing 115 of the diode pack 10 to a grounding connection, conveying an oil through the electrically conductive oil transfer tube 130, and dissipating an electrical charge from the oil to the grounding connection via the electrically conductive oil transfer tube bushing 115.