Light String Surge Protection Using Parallel Capacitors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light strings face issues with surge current damage when an incandescent filament lamp fails, as the closed electrical path is interrupted, and existing capacitor shunt solutions are inefficient and costly for high-power incandescent lamps.
Innovation Solution
A series-connected light string with each incandescent filament lamp connected in parallel to a polarized electrolytic capacitor, which absorbs surge current and maintains the electrical path by charging and discharging, preventing over-voltage damage to remaining lamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor shunt is used across terminals of each LED light to maintain current flow when one LED fails, then the light string remains illuminated, but the voltage drop across remaining LED lights rises significantly causing them to burn up
Solution Approach 1:
The patent changes the electrical parameters of the circuit by introducing a resistive element (light guide member with embedded resistor) that transforms the circuit configuration. This resistor limits the current flow and prevents excessive voltage drop across remaining LEDs, thereby protecting them from over-voltage damage while maintaining illumination continuity.
Solution Approach 2:
The light guide member acts as an intermediary element between the power source and the LED lights. It contains an embedded resistor that mediates the current distribution, preventing direct over-voltage conditions from affecting remaining functional LEDs when one fails.
2Reliability
If a break-down capacitor is used in parallel with each incandescent filament lamp to maintain electrical path when lamp fails, then the closed path for current flow is maintained, but the manufacturing cost becomes too high
Solution Approach 1:
The patent replaces expensive break-down capacitors with a more economical solution using a light guide member containing an embedded resistor. This resistor-based approach achieves the same electrical path continuity function at a lower manufacturing cost, making the system more economically viable for mass production.
Solution Approach 2:
The invention changes the component type from a capacitive element to a resistive element within the light guide member. This parameter change in the electrical component type significantly reduces manufacturing cost while maintaining the essential function of providing a closed electrical path when an incandescent lamp fails.
3Reliability
If incandescent filament lamps are connected in series to mains electricity, then the voltage per lamp is reduced to safe levels, but surge current is generated that can burn out the lamp bulb
Solution Approach 1:
The patent implements beforehand cushioning by incorporating a surge protection mechanism in the form of a resistive element within the light guide member. This resistor acts as a cushion that absorbs and limits surge current before it can reach and damage the incandescent filament lamps, protecting them from current spikes during power-on or fault conditions.
Solution Approach 2:
The light guide member with its embedded resistor serves as an intermediary protective element between the power supply and the incandescent lamps. It mediates the surge current by providing a resistive path that limits current magnitude, thereby protecting the lamps from burnout while still allowing normal operation.
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 absorbs surge currents and maintains the electrical path even when a lamp fails, preventing over-voltage damage and extending the lifespan of remaining lamps, while being cost-effective and suitable for both incandescent and LED lights.
Implementation Method 1
Each incandescent filament lamp is connected in parallel to a capacitor. The capacitors are polarized electrolytic capacitors. When the light string is powered on, the capacitor is charged and absorbs the surge current which may occur.
Implementation Method 2
When the filament of the incandescent filament lamp fails and the bulb remains in the light string, or when the bulb is removed from its socket for replacement, the capacitor with which the failed or removed one of lamps is connected to in parallel operates normally and is charged and discharged to realize electrical connection
Data Source
AI summary
A light string includes a plurality of incandescent filament lamps. The incandescent filament lamps are electrically connected in series and powered by an AC power supply. Each incandescent filament lamp is connected in parallel to a capacitor. The capacitors are polarized electrolytic capacitors. A capacitance of each capacitor is 47 microfarads˜120 microfarads. A rated voltage of each capacitor is 16 volts ˜100 volts and is higher than a rated voltage of each incandescent filament lamp. When one of the incandescent filament lamps is failed, the capacitor with which the failed one of the incandescent filament lamps is connected in parallel operates normally and performs power compensation and electrical connection during its repeatedly charging and discharging. When the light string is powered on, the capacitor is charged and absorbs the surge current which may occur. Thus, the voltage dropped on each light rises slowly and the lights are safe.