Burden Regulation Stage for Current Transformer Saturation
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Solution Overview
Problem
Current power supply and measuring devices for Intelligent Electronic Devices (IEDs) in low voltage or medium voltage switchgears are bulky, expensive, and prone to saturation, leading to harmonic distortion due to multiple current transformers and varying electric loads, which complicates accurate current measurement.
Innovation Solution
An electronic power supply and measuring device with a burden regulation stage that maintains the current transformer out of saturation by regulating the equivalent electric load, using a rectifying stage and current measuring stage with sensing resistors to provide accurate current measurement without additional transformers, thus reducing size, weight, and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current transformers are used to provide power and measure current, then current measurement capability is improved, but device size and weight increase
Solution Approach 1:
The patent combines the power supply function and current measurement function into a single current transformer device. The primary winding is connected to the power line for both power derivation and current sensing, while the secondary winding provides both power to the electronic device and measurement signal. This merging eliminates the need for separate current transformers, reducing device size and weight while maintaining measurement capability.
2Measurement precision
If multiple current transformers are used to provide power and measure current, then current measurement capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines the power supply function and current measurement function into a single current transformer device. The primary winding is connected to the power line for both power derivation and current sensing, while the secondary winding provides both power to the electronic device and measurement signal. This merging eliminates the need for separate current transformers, reducing device size and weight while maintaining measurement capability.
3Adaptability or versatility
If the burden rating of the current transformer is exceeded due to varying electric load, then power supply adaptability is improved, but measurement accuracy deteriorates due to saturation
Solution Approach 1:
The patent introduces a dynamic burden regulation mechanism that adjusts the equivalent burden on the current transformer based on the electronic device's power consumption state. When the device consumes more power, the burden is reduced to prevent saturation; when power consumption is low, the burden is increased to maintain measurement accuracy. This dynamic adjustment allows the system to adapt to varying load conditions while maintaining linear operation and measurement accuracy.
Solution Approach 2:
The patent implements a feedback control mechanism where the control unit monitors the power consumption state of the electronic device and adjusts the burden regulation accordingly. The control unit receives information about the device's operational state and modulates the burden to maintain optimal current transformer performance, ensuring both power supply adequacy and measurement accuracy under varying load conditions.
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 linear operation of the current transformer, providing accurate current measurements and reducing the overall size and manufacturing costs of the device while maintaining transformer efficiency across varying loads.
Implementation Method 1
a current transformer (2) operatively associated to a main power line (10) for deriving the electric power needed for supplying the IED
Implementation Method 2
a rectifying stage, which receives the transformer current provided by the secondary winding and provides a rectified current
Data Source
AI summary
The present invention relates to a power supply and measuring device for an electronic device (e.g. an IED), which is configured to provide supervision, control, protection, communication and/or monitoring functionalities for LV or MV circuits or apparatuses. The power supply device comprises a current transformer, which is operatively associated to a main power line. An input section of the power supply device comprises a burden regulating stage that is configured to regulate the equivalent electric load at the secondary winding of said current transformer. An output section of the power supply device provides a supply voltage suitable to feed said electronic device.