Relay Cycle Life Extender Using Bypass Switch
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Solution Overview
Problem
Relays experience a significant reduction in the number of open/close cycles due to excessive arcing and electro-migration issues when switching high currents, leading to premature failure, particularly in applications like steam humidifiers that require frequent relay operations.
Innovation Solution
Incorporating a bypass switch that temporarily diverts current around the relay during state changes, reducing the abrupt flow of current through the electromechanical switch, and using TRIACs in parallel to manage high currents, with a controller managing enable signals to optimize relay operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the relay switches high current directly, then the current switching function is achieved, but the relay contacts experience excessive arcing and electro-migration leading to reduced cycle life
Solution Approach 1:
The patent introduces a bypass switch as an intermediary component that temporarily carries the high current during relay state transitions. This mediator protects the relay contacts from direct exposure to high current stress during switching events, thereby reducing arcing and electro-migration while maintaining the relay's current switching function.
Solution Approach 2:
The bypass switch is activated in advance before the relay contacts close, and remains active during the transition period. This preliminary action ensures that the high current path is already established through the bypass switch before the relay contacts engage, preventing current surge damage to the contacts.
2Power
If the relay operates under heavy load current, then the load control function is achieved, but the number of open/close cycles before failure decreases
Solution Approach 1:
The bypass switch serves as a protective intermediary that absorbs the mechanical stress of heavy load switching. By diverting the high current through this separate path during transitions, the relay contacts are shielded from the most damaging aspects of heavy load operation, extending their operational lifespan.
Solution Approach 2:
The bypass switch provides beforehand cushioning by being pre-positioned to handle the high current during the critical transition period. This protective mechanism is in place before damage can occur to the relay contacts, cushioning them against the harmful effects of heavy load switching.
3Speed
If the current flows abruptly through the relay during state changes, then the switching speed is maintained, but the relay contacts suffer from excessive arcing
Solution Approach 1:
The bypass switch acts as an intermediary current path that handles the abrupt current changes during switching. This mediator absorbs the harmful arcing effects that would otherwise occur at the relay contacts, allowing fast switching to be maintained without contact damage.
Solution Approach 2:
The harmful arcing effect is extracted from the relay contacts and relocated to the bypass switch. By separating the current switching function from the contact switching function during transitions, the arcing occurs in a component designed to handle it, protecting the relay contacts.
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 approach substantially increases the number of open/close cycles a relay can perform before failure, thereby extending its lifetime and improving reliability in high-load applications.
Implementation Method 1
A control input is used to control the state of the electromechanical switch. In some cases, the control input may pass a control current though a coil of an electromagnet, which then magnetically sets the electromechanical switch to a particular state.
Implementation Method 2
A bypass switch may be connected between the input port of the relay and the output port. The bypass switch is temporarily activated to temporarily divert at least some current around the relay (bypass the relay) while the relay switches states.
Data Source
AI summary
A relay assembly that includes a relay, a bypass switch and a controller. The relay includes an electromechanical switch with an open state and a closed state. The bypass switch is operatively coupled in parallel with the electromechanical switch of the relay, and also has an open state and a closed state. The controller is operatively coupled to the relay and the bypass switch, and is configured to switch the bypass switch from the open state to the closed state, then switch the relay between the open state and closed state, and then switch the bypass switch back to the open state. In some cases, the bypass switch includes a TRIAC. The controller may be configured to maintain the bypass switch in the closed state for less than 100 milliseconds before switching back to the open state.