Leakage current is generated according to the power style desired by many facilities or electrical components. Because they are interconnected, they occur in a wide range. So, when a problem occurs, it is difficult to determine the cause of the problem and the faulty area. This may lead to facility failure for a long period of time or cause an electric shock problem due to human body contact. Therefore, the technology for analyzing the cause of leakage current and identifying the failure point is It must be applied indispensably to prevent equipment failure and protect human body. Leakage current inspection can begin by distinguishing between resistance and capacitance. After classifying the form, it is basic to classify into three categories: origin, transmission route, and damage source. Step 1: Selection of measurement instruments and derivation of utilization method: Measure using instruments such as leakage current meter, oscilloscope to distinguish capacitive/resistive Step 2: Establishment of standards for determining the possibility of failure: Establishment of criteria for determining the possibility of failure. For the purpose of research, legal regulations were reviewed and the facility ELB settings were checked. Step 3: Categorize solutions by problem type: Collect and classify cases of various leakage current problem types and classify causes of leakage current problems into four main categories The above methodology resulted in four major results. 1. Cable short-circuit or electrical device insulation breakdown: Leakage current occurred due to cable damage, so only ELB of the main circuit breaker continued to trip, and the entire power supply was continuously turned off. 2. Charging state due to poor grounding: The leakage current generated from the inverter was continuously charged in the RGV enclosure due to the disconnection of the ground wire, and the enclosure voltage rose to 6.65V. 3. ELB malfunction due to harmonics generated from switching parts: It was a phenomenon in which ELB was intermittently turned off due to capacitive leakage current generated by NC, etc. 4. Malfunction due to improper sensitivity current setting: It was a case where the sensitive current setting value was sensitively set when compared to the normal leakage current value of the facility. There are similarities when accidents occur in large factories such as automobile factories by analyzing cases centering on accidents that occur in production factories. It is necessary to confirm that the same concept is applied to facilities or devices that utilize small power. In addition, since all operations are performed manually, there is a disadvantage in that non-experts cannot check and predict diagnosis. If an automatic leakage current data analysis program is developed, data extraction and analysis, interlocking with upper network data, and automation, the diagnosis efficiency will be improved. When an earth leakage breaker trip occurs, it is often used by replacing it with an overcurrent breaker without solving the cause. This is because when a leakage current problem occurs, equipment is stopped for a long time, and it is difficult to determine the location and cause of the problem. Therefore, a measuring instrument was introduced to measure the leakage current, various references were accumulated, and a method for easily diagnosing and analyzing the cause and point of the problem was developed. In this study, solutions for each type of problem caused by leakage current were categorized, and based on this, a leakage current fault inspection and management plan was developed. Through this, it is possible to determine the cause of the leakage current problem and the point of failure which is the most difficult point of the leakage current problem. It is used for inspection work. we plan to expand the analysis function by developing an automatic leakage current data analysis program.
Mr. JUHEON HWANG, Senior Manager, Hyundai Motors