Thorium-Tungsten Probe Tip for High Current Testing
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Solution Overview
Problem
Conventional conductive test probes experience high resistance and arcing issues when measuring high current circuits, leading to measurement errors and potential damage, which affects the accuracy and durability of the probes.
Innovation Solution
A conductive probe with a thorium-tungsten tip mounted on a metal probe body, featuring a compact geometry with a buried end and a narrowed contact surface to minimize contact resistance and withstand arcing, ensuring low resistance and durability during high current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metallic test probes (brass or steel) are used for high current measurements, then the probe can conduct moderate current flows (less than 1 to 10 amps), but the test probe resistance becomes too high (e.g., 100 mΩ) to achieve accurate measurement resolution (10 mΩ) for high current circuits
Solution Approach 1:
The test probe uses a composite material structure combining copper (high conductivity) and tungsten (high strength, low resistivity). The copper body provides excellent electrical conductivity for low resistance measurements, while the tungsten tip provides mechanical strength and resistance to arcing damage. This composite approach achieves both low test probe resistance for high measurement precision and durability for high current applications.
2Ease of operation
If conventional metallic test probes are used in high current circuits, then the probe can make contact with circuit nodes, but electrical arcing occurs that melts the metal, causes material damage, and permanently increases test probe resistance
Solution Approach 1:
The tungsten component in the composite probe tip has extremely high melting point and strength, providing resistance to arcing damage. The copper body provides good electrical conductivity. Together, they enable the probe to withstand high current arcing conditions without melting or degrading, maintaining reliability and contact capability.
Solution Approach 2:
The probe uses different materials for different parts: copper for the body where high conductivity is needed, and tungsten for the tip where resistance to arcing and mechanical wear is critical. This local differentiation of material properties optimizes both ease of operation and reliability.
3Reliability
If the test probe geometry is altered to reduce resistance for high current applications, then the probe can conduct higher currents, but the probe becomes more susceptible to arc damage and requires frequent replacement
Solution Approach 1:
The copper-tungsten composite structure allows the probe to maintain low resistance (copper body) while being protected from arc damage (tungsten tip). The tungsten tip's high melting point and strength prevent the geometric alterations that would otherwise be needed to reduce resistance, thereby extending probe lifespan without sacrificing electrical performance.
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 thorium-tungsten probe tip maintains low resistance and immunity to arcing, preventing measurement errors and prolonging the probe's lifespan, while maintaining accurate arc detection and high-resolution measurements.
Implementation Method 1
A conductive probe having a probe body for communicating with a circuit tester or a jumper. The probe body may be comprised of metal and has a free end. A probe tip comprised of thorium-tungsten may be mounted to the free end of the probe body.
Implementation Method 2
Another cause of poor measurement quality may be electrical arcing that may occur between the test probe and the circuit node being measured. Arcing may generally begin during the making or breaking of contact involving a live circuit in close proximity.
Data Source
AI summary
A conductive probe may include a probe body for communicating with a circuit tester or a jumper. The probe body may be formed of metal and may have a free end. A probe tip may be mounted to the end of the probe body. The probe tip may be formed of thorium-tungsten. The probe tip may be configured for contacting a circuit node.