Mobile DC Breaker Testing Device Using Synchronized Current Pulses
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Solution Overview
Problem
Existing mobile testing devices for high speed DC breakers are heavy, difficult to transport, and produce current profiles with significant ripple, making measurements non-reproducible and impractical for on-site testing, especially since they require a 380 V supply voltage and have limitations in current generation.
Innovation Solution
A portable testing device with a DC voltage source, interconnected cells generating current pulses using capacitors and low pass filters, synchronized to minimize ripple, and controlled by MOSFET switches, allowing for modular design and independent operation from power networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mobile testing device with three-phase rectifier and autotransformer is used, then the device can be transported to on-site locations, but the device weight exceeds 25 kg making it difficult to displace and requiring special lifting equipment
Solution Approach 1:
The testing device is divided into multiple independent modules, each weighing less than 25 kg. Each module contains a DC voltage source, capacitors, switches, and control circuits that can function independently or in combination with other modules, enabling portable deployment while maintaining testing capability.
Solution Approach 2:
The invention changes the operating voltage parameter from standard 380 V AC to DC voltages of 24 V, 48 V, or 72 V. This parameter change enables the use of lighter components and batteries instead of heavy three-phase rectifiers and autotransformers, reducing overall device weight while maintaining sufficient power for testing.
2Power
If a three-phase rectifier with autotransformer is used to generate current, then the device can provide high current, but the current profile contains residual undulation making measurements non-reproducible
Solution Approach 1:
The device uses periodic switching of MOSFETs to charge and discharge capacitors in controlled cycles. This periodic action generates smooth current pulses without the residual undulation characteristic of three-phase rectifiers, enabling reproducible measurements while maintaining high current capability.
Solution Approach 2:
The invention replaces the mechanical autotransformer system with an electronic switching system using MOSFETs and capacitors. This substitution eliminates mechanical sliding contacts and their associated ripple, providing cleaner current profiles with better measurement reproducibility.
3Power
If sliding contacts of the autotransformer are used for current generation, then the device can handle high currents, but long cooling down periods are necessary between current generations
Solution Approach 1:
The invention replaces mechanical sliding contacts with solid-state MOSFET switches and capacitor-based energy storage. This eliminates the need for mechanical contact and subsequent cooling periods, allowing immediate sequential testing without time loss.
Solution Approach 2:
The capacitors are pre-charged to the required voltage levels before current generation begins. This preliminary energy storage allows immediate high-current discharge without waiting for previous thermal cycles to complete, eliminating cooling down periods.
4Power
If a three-phase rectifier system is used, then the device can generate high current, but a supply voltage of 380 V must be available on-site limiting portable operation
Solution Approach 1:
The invention changes the power source parameter from 380 V AC mains power to DC batteries with voltages of 24 V, 48 V, or 72 V. This enables independent portable operation without requiring external power infrastructure, while the capacitor-based system maintains the ability to generate high testing currents.
Solution Approach 2:
The DC battery-based system with capacitor energy storage can operate independently of external power sources, providing universal applicability across different testing locations without requiring 380 V supply availability. The same system architecture supports various voltage configurations.
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 results in a significantly lighter device capable of generating high currents with minimal ripple, enabling reproducible measurements and flexible current profiles, suitable for on-site testing of high speed DC breakers, with each module weighing under 25 kg and capable of producing currents up to 15000A.
Implementation Method 1
each cell comprises a first capacitor, connected in parallel with the DC voltage source
Implementation Method 2
a first low pass filter, connected in parallel with the first capacitor, the first low pass filter comprising a second capacitor
Data Source
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AI summary
This invention relates to a testing device for testing of high speed DC breakers, which due to its weight can be made mobile, comprising means for generating high currents with minimal ripple in a reproducible way, for sending through the high speed DC breakers at testing, wherein the current generating means comprise several cells (A) for generating current pulses, which are interconnected in parallel into a power unit (A'), wherein each cell (A) comprises a capacitor (C2), which is connectable in parallel with a DC voltage source (V), and a switch (S) for intermittently loading and unloading the capacitor (C2), in order to create the current pulses and wherein the current generating means comprise synchronisation means (F) for synchronising the intermittent opening and closing of the switches (S) of the different cells (A), such that the current pulses of different cells (A) are shifted in time with respect to each other.