scholarly journals The Effects of High-Frequency Residual Currents on the Operation of Residual Current Devices

2021 ◽  
Vol 19 ◽  
pp. 67-72
Author(s):  
T. M. H. Slangen ◽  
◽  
B. R. F. Lustenhouwer ◽  
V. Cuk ◽  
J. F. G. Cobben
Keyword(s):  
High Frequency ◽  
Residual Current ◽  
Power Electronic ◽  
Leakage Currents ◽  
Important Conclusion ◽  
Large Power ◽  
Residual Currents ◽  
Safety Risks ◽  
Set Up ◽  
Frequency Current

This research investigates the effects of high frequency currents between 50 Hz and 150 kHz on the operation of Residual Current Devices (RCDs). Nowadays, the increasing amount of large power-electronic switching devices can be a source of both harmonics (<2 kHz) and supraharmonics (2-150 kHz) currents injected to the grid. This can have several effects and possibly lead to unwanted tripping of RCDs, due to high earth-currents that can be emitted by the devices. The question is if supraharmonics can also lead to misoperation or fail-to-operate conditions for the RCDs, potentially leading to serious safety risks. A set-up is developed to introduce both 50 Hz and highfrequency leakage currents. First, the 50 Hz tripping-current of the RCDs is tested under nominal conditions. Secondly, the tripping current for non-nominal frequencies (between 50 Hz and 150 kHz) is determined to verify the possibility for false tripping. Lastly, the 50 Hz tripping current for the RCD is tested in the presence of a high-frequency current. The most important conclusion is that RCDs of type A and AC have an increased fundamental (50 Hz) tripping current when there are HFcomponents present. This potentially results in a safety risk.

scholarly journals Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1997 ◽  
Author(s):  
Jun Jiang ◽  
Mingxin Zhao ◽  
Chaohai Zhang ◽  
Min Chen ◽  
Haojun Liu ◽  
...  
Keyword(s):  
High Frequency ◽  
Partial Discharge ◽  
Phase Region ◽  
High Frequency Current ◽  
System A ◽  
Mode Decomposition ◽  
Current Transducer ◽  
Core Components ◽  
Set Up ◽  
Frequency Current

High-frequency transformers are the core components of power electronic transformers (PET), whose insulation is deeply threatened by high voltage (HV) and high frequency (HF). The partial discharge (PD) test is an effective method to assess an electrical insulation system. A PD measurement platform applying different frequencies was set up in this manuscript. PD signals were acquired with a high-frequency current transducer (HFCT). For improving the signal-to-noise (SNR) ratio of PD pulses, empirical mode decomposition (EMD) was used to increase the SNR by 4 dB. PD characteristic parameters such as partial discharge inception voltage (PDIV) and PD phase, number, and magnitude were all analyzed as frequency dependent. High frequency led to high PDIV and a smaller discharge phase region. PD number and magnitude were first up and then down as the frequency increased. As a result, a suitable frequency for evaluating the insulation of high-frequency transformers is proposed at 8 kHz according to this work.

scholarly journals Measurement and Analysis of Ocean Current using High- Frequency (HF) Radar Observation in the Bali Strait

2021 ◽  
Vol 893 (1) ◽  
pp. 012053
Author(s):  
R Firdaus ◽  
E L Siadari ◽  
F Alfahmi
Keyword(s):  
Harmonic Analysis ◽  
High Frequency ◽  
Weather Condition ◽  
Current Data ◽  
Residual Current ◽  
Hf Radar ◽  
Ocean Current ◽  
Random Pattern ◽  
Residual Currents ◽  
Adcp Data

Abstract High-Frequency (HF) Radar is an instrument using radio waves to measure ocean currents and waves remotely. This technology has many advantages, including has unprecedented spatial and temporal resolution, can operate in any weather condition, and is not dangerous for the environment. However, HF Radar's research is still limited in Indonesia. This research aimed to analyze the tidal and residual current in the Bali Strait in July 2020. Radial velocity from two HF Radar sites is combined to obtain the total currents. Current data from HF Radar were compared with Acoustic Doppler Current Profiler (ADCP) data to investigate its accuracy. Surface current data were analyzed using harmonic analysis to separate tidal and residual currents. Comparison between HF Radar and ADCP data are in good agreement for meridional current with a very high correlation of 0.813 and a small RMSE value of 0.22 m/s. Harmonic analysis shows that the dominant currents are tidal currents. The current direction was northward (southward) at flood (ebb), with maximum northward (southward) velocities are 2.17 m/s (2.97 m/s), respectively. The residual current has a random pattern, slightly faster northward than southward, and has similar spectral with the wind.

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