Varistor Thermal Protection with Segmented Trigger Zones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surge protectors face challenges in safely disconnecting varistors due to thermal runaway, which can lead to overheating or fire, and existing thermal disconnection methods are either slow or influenced by electrical contact resistance, compromising protection during overvoltages.
Innovation Solution
A thermal protection device with separate trigger zones for each varistor allows for independent disconnection of varistors from the electrical network, avoiding the influence of electrical contact resistance and ensuring quick disconnection within 5 seconds, even if one varistor fails, thus maintaining protection and preventing poor protection during overvoltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing thermal disconnection methods are used, then thermal runaway protection is provided, but disconnection is slow or influenced by electrical contact resistance
Solution Approach 1:
The patent divides the thermal protection system into separate trigger zones for each varistor, with independent thermal detectors and movable contact arms. This segmentation allows each varistor to be monitored and disconnected independently, eliminating the influence of electrical contact resistance from shared connection terminals and enabling faster, more reliable disconnection.
Solution Approach 2:
The patent introduces movable contact arms as intermediary elements between the thermal detectors and the varistor connection terminals. These contact arms provide a mechanical disconnection path that is independent of the electrical connection terminals, thereby eliminating the influence of electrical contact resistance on the thermal disconnection process.
2Power
If varistors are connected in parallel for high power protection, then lightning protection capability is improved, but thermal runaway risk increases
Solution Approach 1:
The patent implements separate trigger zones and independent thermal detection for each varistor in the parallel configuration. This allows individual monitoring and disconnection of each varistor, preventing thermal runaway from affecting other varistors in the parallel arrangement and enabling higher power protection with reduced risk.
Solution Approach 2:
The patent employs thermal detectors that continuously monitor each varistor's temperature and trigger disconnection before thermal runaway can propagate to other components. This preliminary detection and isolation action prevents the harmful effects of thermal runaway in high-power parallel varistor configurations.
3Device complexity
If electrical connection terminals are used for both electrical connection and thermal triggering, then device complexity is reduced, but measurement precision of thermal runaway detection is compromised
Solution Approach 1:
The patent separates the electrical connection function from the thermal triggering function by creating distinct trigger zones and using movable contact arms for thermal disconnection. This segmentation ensures that thermal runaway detection is not influenced by electrical contact resistance, improving detection precision while maintaining reasonable device complexity.
Solution Approach 2:
The patent introduces movable contact arms as intermediary elements that provide a mechanical disconnection path independent of the electrical connection terminals. This intermediary mechanism ensures accurate thermal runaway detection by eliminating the confounding effect of electrical contact resistance on the thermal triggering process.
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 solution ensures reliable and rapid disconnection of faulty varistors, preventing overheating and maintaining effective lightning protection, while avoiding the risks associated with thermal runaway and electrical arc formation.
Implementation Method 1
a first trigger zone (200a) arranged to trigger, when a first thermal detector (10a) detects thermal runaway of the first varistor (1a)
Implementation Method 2
capable of triggering, when a second seal (101b) of a second thermal detector (10b) is unsealed
Implementation Method 3
cause the first movable contact arm (A120a) to move into a disconnected position in which the second movable contact arm (A120b) is intended to disconnect from the first electrical connection terminal (A12) of the first varistor (1a)
Implementation Method 4
in the event of an overvoltage, the resistance of the varistor drops allowing discharge to the ground and thus protect the electrical installation
Implementation Method 5
the solder melts above a predetermined temperature and causes a disconnection of the varistor allowing the movement of this element with the effect of opening the varistor circuit
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D
AI summary
One aspect of the invention relates to an electrical device against transient overvoltages (A) intended to receive a set of varistors (1ab), comprising: - a movable contact arm (A120a, A120b) per varistor, intended to be connected independently to a power supply network or to earth, in an initial position to be in contact with an electrical connection terminal (120a) of the corresponding varistor (1a, 1b), - a thermal protection device (2) comprising a tripping zone (200a) per varistor different from each other, each intended to trip when a seal of a thermal detector (10a, 10b) of the corresponding varistor is unsealed, to cause the movement of the corresponding movable contact arm (A120a, A120b) into a disconnected position in which the movable contact arm is intended to disconnect from the first connection terminal (120a, 120b) of the corresponding varistor.