Controlled Earthing for Loop Impedance Measurement in Unearthed Power Systems
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Solution Overview
Problem
Measuring loop impedance in ungrounded power supply systems requires manual grounding of live conductors, which is labor-intensive and inefficient, especially in environments like hospitals where recurring interventions are undesirable.
Innovation Solution
A measuring arrangement with a controlled earthing device and a unidirectional communication channel using the fault current loop for automated grounding and measurement, eliminating the need for manual interventions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual grounding of active conductors is performed to enable loop impedance measurement in unearthed power supply systems, then the measurement can be carried out according to standard methods, but the process becomes cumbersome and requires recurring manual interventions by qualified electricians
Solution Approach 1:
The measuring device automatically performs the grounding function that previously required manual intervention by qualified electricians. The device includes an automated earthing arrangement that can establish the necessary earth connection on its own, eliminating the need for human operators to physically ground conductors at the distribution board.
Solution Approach 2:
The measuring device combines multiple functions into a single unit: it performs both the automated earthing operation and the loop impedance measurement. This multi-functional approach replaces the need for separate manual grounding procedures and measurement operations, allowing the device to complete the entire measurement process autonomously.
2Measurement precision
If manual grounding procedures are implemented for loop impedance measurement, then standard measurement methods can be applied, but organizational effort and time are significantly increased
Solution Approach 1:
The measuring device automatically performs the preliminary grounding action before conducting the measurement. The automated earthing arrangement establishes the necessary earth connection as a preliminary step, eliminating the time-consuming manual preparation that previously had to be performed by qualified electricians before measurement could begin.
3Device complexity
If the fault current loop is used as a communication channel for controlling the earthing device, then a unidirectional communication path is established without requiring additional wiring, but the control signal transmission must be reliable amidst fault current conditions
Solution Approach 1:
The fault current loop serves dual functions: it carries both the fault current necessary for impedance measurement and the control signals for operating the earthing device. By making the communication channel multi-functional, the invention eliminates the need for separate communication wiring while utilizing an existing conductive path.
Solution Approach 2:
The control signals are transmitted through the fault current loop using the loop itself as an intermediary medium. The measuring device modulates control information onto the fault current or uses the loop's conductive path to transmit commands to the earthing device, allowing communication without dedicated signal wires.
Data Source
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AI summary
The invention relates to a measuring arrangement and a measuring method for measuring the loop impedance of a fault current loop formed by an active conductor and a protective conductor in an ungrounded power system, with a measuring device connected to a consumption point for measuring a phase-to-ground voltage and calculating the loop impedance. Furthermore, the invention relates to an insulation monitoring device for determining the insulation resistance in an ungrounded power system. The basic idea of the present invention is to arrange a controlled grounding device on the feeder side between the active conductors and the protective conductor.This grounding device is designed to selectively connect one of the active conductors to ground on the supply side, depending on the control information received from the extended measuring device via the communication channel. In conjunction with the extended measuring device located on the load side, it forms a fault current loop whose loop impedance can be measured. The control information is generated by the extended measuring device connected on the load side and remotely transmitted to the grounding device. An insulation monitoring device can be equipped with the described grounding device to expand its functional scope in order to be able to perform a loop impedance measurement in the ungrounded power supply system in addition to insulation monitoring.