| Author: | Zhao, Sihan |
| Title: | Residual current devices (RCDs) and its protection against leakage current in electrical installations |
| Advisors: | Du, Yaping (BSE) |
| Degree: | M.Eng. |
| Year: | 2020 |
| Subject: | Electric circuit-breakers Electricity -- Safety measures Electric wiring -- Safety measures Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building Services Engineering |
| Pages: | xi, 54 pages : color illustrations |
| Language: | English |
| Abstract: | As the leakage protection devices widely used in low-voltage power distribution systems, the biggest problem faced by residual current devices (RCDs) is the unwanted tripping that sometimes occurs for unknown reasons. Another challenge of RCDs is when the fatal leakage current flowing through the RCDs, the circuit cannot be cut off in time and effectively. This is because the true leakage current is not as standard as described in the IEC standards, which causes the RCDs to malfunction. The large-scale use of switching mode power supplies makes the circuit contain a large amount of smooth dc components and high-frequency signals, which poses a huge challenge to the normal operation of the A-type RCD. The B-type RCD is a new type of RCD launched by most mainstream RCDs manufacturers to meet the above challenges. In this paper, the actual leakage current waveform is obtained by designing the actual circuit, and the tripping characteristic curve of different types of RCDs under the different characteristics of the leakage current is obtained. Experimental results show that A-type RCD will not lose its ability to work when the smooth dc component exceeds 6 mA. Compared with A-type RCD, B-type RCD sometimes does not have the huge and obvious advantages advertised by the mainstream RCDs manufacturers. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5348.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 6.19 MB | Adobe PDF | View/Open |
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