DC Relay Inner Contact Structure for Short-Circuit Arc Resistance
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Solution Overview
Problem
High-voltage DC relays face challenges in reducing heat loss and resisting short-circuit currents, leading to contact bouncing and arcing due to electrodynamic repulsion forces, which existing solutions cannot adequately address within volume and power consumption constraints.
Innovation Solution
The design incorporates an inner contact portion on high-voltage DC relays, strategically positioned between stationary contact lead-out terminals, and an anti-short circuit assembly with magnets to resist electrodynamic repulsion forces, reducing contact area and enhancing safety without increasing size or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coil size is increased to improve holding force, then the anti-short circuit current capacity is improved, but the volume and power consumption increase
Solution Approach 1:
The patent applies local quality by creating an inner contact portion with a smaller cross-sectional area at the contact region compared to other parts of the contact lead. This localized structural modification concentrates the current path and reduces the electrodynamic repulsion force specifically at the contact point, allowing the relay to resist short-circuit currents without increasing the overall coil size or power consumption.
2Reliability
If the contact pressure is increased to reduce contact resistance, then the contact reliability is improved, but the electrodynamic repulsion force cannot be resisted and contact bouncing occurs
Solution Approach 1:
The patent changes the geometric parameter of the contact lead by creating an inner contact portion with a reduced cross-sectional area. This parameter change increases the current density and magnetic field concentration at the contact point, which enhances the holding force through electromagnetic interaction while the localized structure resists the electrodynamic repulsion force, preventing contact bouncing even at high contact pressures.
3Reliability
If the coil ampere-turn value is increased to improve holding force, then the anti-short circuit capacity is improved, but the power consumption increases
Solution Approach 1:
The patent applies local quality by modifying only the contact region of the contact lead with an inner contact portion having a smaller cross-sectional area. This localized structural change enhances the electromagnetic interaction and holding force at the critical contact point without requiring an increase in the overall coil ampere-turns, thereby maintaining low power consumption while improving anti-short circuit capacity.
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
This configuration effectively reduces electrodynamic repulsion forces, preventing arcing and improving safety while meeting requirements for reduced heat loss and increased anti-short circuit capacity without enlarging the relay.
Implementation Method 1
the electrodynamic repulsion force generated by the short-circuit current
Implementation Method 2
an anti-short circuit assembly with magnets to resist electrodynamic repulsion forces
Data Source
AI summary
A relay includes a contact assembly, the contact assembly includes a movable contact piece and a pair of stationary contact lead-out terminals, the movable contact piece is configured to contact with or separate from the pair of stationary contact lead-out terminals. At least one of the sides of the stationary contact lead-out terminals and the movable contact piece close to each other is provided with an inner contact portion, and the stationary contact lead-out terminals and the movable contact piece are abutted only by the inner contact portion, and the inner contact portion is disposed on a side where the pair of stationary contact lead-out terminals are close to each other.