Intelligent Power Strip Relay Switching for In-Rush Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rack power distribution units (RPDUs) fail to mitigate in-rush currents during manual connection/disconnection of load devices and lack the ability to detect load connectivity, leading to potential damage to relay contacts and circuit breakers.
Innovation Solution
A rack power distribution unit (RPDU) with processors managing bistable relays, using control algorithms to identify relay contact status and predict voltage zero-crossing events, minimizing in-rush current by safely switching power based on load impedance and zero-crossing timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power relays are used to switch receptacles for rebooting connected devices, then the switching function is achieved, but substantial in-rush currents occur when bulk capacitors charge, causing relay contact damage
Solution Approach 1:
The system detects load connection status in advance using voltage sensing circuitry and control algorithms before closing the relay contact. By identifying when a load is already connected while the contact is open, the system prevents premature closure that would cause in-rush current, thus protecting the relay contact from damage
Solution Approach 2:
The system continuously monitors voltage across the relay contact using voltage sensing circuitry and uses control algorithms to determine load connection status. This feedback mechanism allows the system to make intelligent decisions about when to close the contact, avoiding conditions that would generate harmful in-rush currents
2Reliability
If RPDUs sequence power to each receptacle to ensure upstream breakers do not trip, then circuit protection is improved, but the system cannot mitigate in-rush current when users manually connect/disconnect loads while powered
Solution Approach 1:
The system autonomously monitors its own state by detecting whether a load is connected while the relay contact is open using voltage sensing and control algorithms. This self-service capability enables the system to automatically prevent in-rush current conditions without requiring external control or user intervention
Solution Approach 2:
The voltage sensing circuitry continuously checks for load connection status before the relay contact closes. This preliminary detection allows the system to predict and prevent in-rush current conditions that would occur during manual load connection, extending protection beyond automated sequencing scenarios
3Use of energy by moving object
If bistable relays are used to reduce energy consumption by pulsing the coil, then energy efficiency is improved, but the system lacks continuous contact monitoring capability
Solution Approach 1:
The voltage sensing circuitry continuously monitors the voltage across the relay contact and provides feedback to the control algorithm. This feedback mechanism enables the system to determine load connection status at all times, including when the relay contact is open, without requiring continuous coil energization
Solution Approach 2:
The voltage sensing circuitry serves multiple functions: it monitors relay contact status, detects load connection state, and provides information for in-rush current prevention decisions. This multi-functionality compensates for the lack of continuous monitoring in bistable relays while maintaining energy efficiency
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
Effectively minimizes in-rush currents during manual power connections/disconnections, preventing relay contact damage and circuit breaker tripping, while ensuring safe and efficient power management.
Implementation Method 1
identifying relay contact status (open/closed) based on changes in RMS or peak voltage influenced by the load impedance
Implementation Method 2
The RPDU is also configured to predict timings for voltage zero-crossing events
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The present disclosure is directed to a rack power distribution unit (RPDU, 100) that automatically and safely switches power to one or more receptacles (192). The RPDU includes one or more processors (132a-n, 164) utilizing control algorithms that manage bistable relays (140) so that in-rush current is minimized upon manual connection/disconnection of power to a load device. In particular, relay contact status (open/closed) is identified based on changes in RMS or peak voltage influenced by the load impedance. The RPDU is also configured to predict timings for voltage zero-crossing events. In this manner, and based on the determination of relay contact status and voltage zero-crossing prediction, open relay contacts are identified and safely closed at voltage zero-crossing. Fig. 1