Multifunctional Test Current for IT Power Supply Insulation Fault Search
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
IT power supply systems face challenges with excess voltage, displacement direct voltage, and subsystem shutdown issues, particularly in complex systems where equipment designed for grounded systems are used, leading to potential safety risks and inefficiencies in fault detection and isolation.
Innovation Solution
A multifunctional test current is generated and fed into the IT power supply system to act as a voltage compensation current, tripping current, and leakage-capacitance compensation current, allowing for selective subsystem shutdown and reducing capacitive leakage current risks, while monitoring insulation resistance and compensating for voltage increases and displacement direct voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first insulation fault occurs in an IT power supply system, then continuous power supply is maintained, but excess voltage occurs on other active conductors causing safety risks
Solution Approach 1:
The patent applies preliminary anti-action by feeding a test current into the IT power supply system before a second fault occurs. This test current compensates for the excess voltage caused by the first insulation fault, preventing the harmful voltage from reaching dangerous levels. The insulation monitoring device continuously monitors the insulation resistance and triggers the test current feeding when the first fault is detected, thereby preemptively counteracting the excess voltage hazard while maintaining continuous power supply.
Solution Approach 2:
The patent converts the harmful excess voltage into a beneficial effect by using the same test current that causes the voltage compensation as a locating current for fault detection. The test current, when registered by measuring-current transformers in subsystems, enables the insulation-fault search to locate the first insulation fault. Thus, the current that could be considered harmful (causing voltage shifts) is transformed into a useful tool for both compensation and fault localization.
2Device complexity
If equipment designed for grounded systems is used in IT systems, then system complexity is reduced, but displacement direct voltage occurs causing safety risks
Solution Approach 1:
The patent applies preliminary anti-action by continuously monitoring the displacement direct voltage caused by equipment designed for grounded systems used in IT configurations. When the displacement voltage exceeds a threshold, the insulation monitoring device triggers the feeding of test current that compensates for this harmful voltage, preventing safety risks before they occur.
Solution Approach 2:
The patent changes the electrical parameters of the system by introducing a compensating test current that alters the voltage distribution in the IT power supply system. This parameter change (adding compensating current) counteracts the displacement direct voltage caused by the mismatch between equipment design and system type, thereby eliminating the harmful effect while maintaining the simplicity of using standard equipment.
3Measurement precision
If insulation-fault search is performed using conventional methods, then fault location is achieved, but selective subsystem shutdown is not possible
Solution Approach 1:
The patent applies universality by making the test current serve multiple functions simultaneously. The same test current fed into the IT power supply system acts as both a locating current for insulation-fault search and a tripping current for selective subsystem shutdown. By monitoring the test current registration in different subsystems and evaluating the results, the system can both locate the insulation fault and trigger shutdown of the specific affected subsystem, thereby achieving both functions with a single current feeding mechanism.
4Measurement precision
If test current is fed for insulation-fault search, then fault location is improved, but capacitive leakage current risks increase
Solution Approach 1:
The patent applies parameter changes by carefully controlling the frequency and amplitude of the test current. By selecting an appropriate frequency range (e.g., 15-65 Hz) and adjusting the current parameters based on system conditions, the patent optimizes the test current to achieve sufficient fault location precision while minimizing the excitation of capacitive leakage currents. The insulation monitoring device adapts the test current parameters to balance measurement effectiveness with safety.
Data Source
AI summary
The invention relates to a method and to devices for extended insulation-fault search in an IT power supply system using a multifunctional test current, wherein, selectively and depending on the application, the test current functions as a voltage compensation current so as to compensate a voltage increase in an active conductor of the IT power supply system, as a tripping current so as to trip a residual current protection device arranged in a subsystem of the IT power supply system and/or as a leakage-capacitance compensation current so as to compensate a capacitive leakage current. The test current can fulfil more than one of the cited functions simultaneously.