Transient Voltage Protection Circuit with TSPD and Transorb
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Solution Overview
Problem
Existing transient voltage protection circuits are inadequate for all significant transient voltage conditions, often requiring large physical size to handle high currents and may not operate effectively during high temperature environments, while also risking fuse blowout during transient events.
Innovation Solution
A transient voltage protection circuit comprising a series combination of a thyristor surge protection device (TSPD), a transorb diode, and a resistor, coupled in parallel with the load, and a fuse, which limits current and voltage to prevent damage, allowing for compact design and self-resetting functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parallel protection circuit is used to shunt transient voltage current, then the load is protected from transient voltages, but the circuit requires high change in voltage with respect to time to operate and may not operate for all significant transient voltage conditions
Solution Approach 1:
The patent changes the operational parameters of the protection circuit by using a series combination of a switching element and limiting element instead of a simple parallel clamp. This configuration allows the circuit to operate with smaller changes in voltage over time, enabling it to respond to a broader range of transient voltage conditions including those with slower rise times.
2Reliability
If a parallel protection circuit shunts very high currents from the load, then the load is protected, but the circuit becomes physically large to accommodate significant heat dissipation
Solution Approach 1:
The patent segments the protection function into two distinct elements: a switching element (such as a TVS diode or SCR) that responds to transient voltages, and a limiting element (such as a gas discharge tube or arc suppressor) that handles the high current shunting. This segmentation allows each element to be optimized for its specific function, enabling the circuit to shunt very high currents while maintaining a compact physical size.
3Object-affected harmful factors
If a fuse is used in the protection circuit, then overcurrent protection is provided, but the fuse may blow during transient voltage events
Solution Approach 1:
The patent introduces a current-limiting element as an intermediary between the transient voltage source and the fuse. This limiting element (such as a gas discharge tube or arc suppressor) has characteristics that allow it to limit the current during transient events, preventing the fuse from blowing while still providing overcurrent protection. The intermediary element absorbs the transient energy without triggering the fuse.
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 effectively limits transient voltages to protect sensitive loads from damage, maintains a compact size, and prevents fuse blowout, ensuring reliable operation across various conditions including high temperatures.
Implementation Method 1
The switching element may exhibit high impedance during normal operation, but may switch on, i.e. close, to shunt current from the load to the limiting element in the event a transient voltage is imparted to the circuit
Implementation Method 2
The limiting element may exhibit a limited voltage drop under high current conditions to thereby limit the input voltage to the load
Data Source
AI summary
A transient voltage protection circuit that protects a load from transient voltages is disclosed. The circuit includes a series combination of a thyristor surge protection device (TSPD), a resistor and a transorb coupled for coupling in parallel with the load, and a fuse coupled between an AC input and the series combination. The TSPD and the transorb are configured to enter a transient mode upon application of a transient voltage to the circuit to shunt current from the load and provide an AC output voltage to the load less than the transient voltage without opening the fuse.