UPS Neutral-Ground Backup Switching for Grid Outage Reliability
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) systems face challenges in efficiently managing terminal connections during grid outages, particularly in maintaining reliable ground connections to prevent device malfunctions and compliance with electrical regulations.
Innovation Solution
A backup switch unit comprising a power relay and a fast switch device (FSD) is used to rapidly connect or disconnect power terminals in response to electrical network conditions, utilizing a controller to monitor and manage electrical parameters, ensuring safe and compliant terminal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a neutral conductor is used to supply ground connection during grid operation, then the ground connection is established, but the ground connection is lost when the neutral conductor is disconnected during grid outage
Solution Approach 1:
The backup switch unit is pre-configured with a bypass path that can be activated when the neutral conductor is disconnected. The controller monitors the neutral conductor status and automatically switches to the backup ground connection path when needed, ensuring continuous ground connection during grid outages without manual intervention.
Solution Approach 2:
The backup switch unit acts as an intermediary between the neutral conductor and the ground connection. It provides an alternative path through a backup switch that can be activated when the neutral-conductor connection is lost, ensuring the ground connection is maintained through this intermediate backup path during grid outages.
2Reliability
If a backup switch unit with power relay and fast switch device is used, then fast and reliable switching is achieved, but device complexity increases
Solution Approach 1:
The backup switch unit is segmented into distinct functional components: a controller for monitoring and decision-making, a power relay for main switching operations, and a fast switch device for rapid response. This segmentation allows each component to perform its specific function optimally while maintaining overall system reliability, with the controller managing the coordination between the relay and fast switch.
Solution Approach 2:
The backup switch unit incorporates dynamic switching capabilities with both a power relay and a fast switch device that can respond to changing electrical conditions. The fast switch device provides rapid switching for transient conditions, while the power relay handles sustained switching needs, creating a dynamic, multi-level response system that adapts to different operational scenarios.
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 provides fast and reliable switching to maintain power terminal connections, reducing the likelihood of device malfunctions and ensuring compliance with electrical regulations during grid disruptions.
Implementation Method 1
A FSD may comprise a solid-state relay, such as a semiconductor device, silicon-controlled rectifier, transistor, or a triac
Implementation Method 2
The power relay in series may be operated by the controller to disconnect the FSD in case of a malfunction of the FSD during operation
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
When a power outage occurs, an uninterruptable power supplies may lose all grid connections including a neutral connection which may be connected to ground. To avoid the loss of a ground connection to the power circuits of the UPS, a switch unit may be used to selectively connect a neutral conductor of the circuit to a ground terminal. The switch unit may comprise a power relay, a fast switch device (FSD), and a controller. The power relay and FSD may be connected in series between the neutral conductor of the circuit and a ground terminal. The controller may be configured to: close the FSD when the voltage between ground and neutral (Vng) goes above a first threshold, open the FSD when the voltage between any grid connection and neutral (Vg) goes above a second threshold, and close the FSD when Vg is below the second threshold.