Construction sites are often very chaotic, characterized by their temporary and unplanned nature, which poses safety hazards. Particularly in terms of temporary electrical usage, wires are often pulled arbitrarily without safety measures. Especially in recent years, multiple accidents resulting in casualties due to electric leakage have occurred. In such situations, Residual Current Protection Relay, as a leakage protection device, becomes crucial in the construction field.
It is mandatory to use residual current protection relays in construction sites to ensure the safety of the power supply. During normal construction, due to the special nature of the site, leakage protection devices often trip, which not only hinders the construction progress but also endangers the safety of the site. By combining the actual conditions of the construction site and the electricity usage, the phenomenon of frequent tripping of leakage protection devices on construction sites is summarized, and daily protection measures for leakage protection devices are provided.
Residual Current Protection Relay primarily functions to provide protection when electrically powered equipment leaks electricity or when there is a fatal risk during a human electric shock. The equipment mainly consists of a switch, test button, tripping device, overall tripping structure, residual current transformer, among other components. The protection facility operates when the ground fault current exceeds the predetermined value, causing the main switch to trip automatically. The faulty current is cut off to a certain extent, providing protection.
During a lightning strike, the process of positive and negative alternating generates overvoltage, which through overhead lines, insulated wires, cables, and electrical connectors' capacitance to the ground, produces ground leakage current, causing the Residual Current Protection Relay to trip falsely, or even directly damage it. Excessive overvoltage can damage the protector's power supply and internal circuits, burn out the tripping coil of an automatic switch with an undervoltage release; insufficient voltage can cause the undervoltage release coil to trip, and the closing control circuit cannot start. Electromagnetic switches with mechanical locking devices may trip slowly or refuse to move due to insufficient tripping power.
Various installed lines and electrical equipment used in construction sites show messy wiring during lighting processes, leading to premature aging of lines, reduced insulation resistance of lines and electrified facilities, current leakage, or even grounding, causing multiple issues with leakage protection devices and affecting normal operation. Because of the reduced insulation resistance of the output terminal lines of the leakage switch and the grounding protection of the zero line, the neutral point of the power supply is not grounded during the installation of leakage protection devices. In the long-term operation, harmful gases continuously corrode and erode, reducing the insulation degree of electronic components such as electromagnetic coils and resulting in mildew and rust, ultimately causing the Residual Current Protection Relay facility to malfunction or refuse to operate.
Common short circuits between phases can generate large currents and can be protected by switches. However, human electric shock, line aging resulting in current leakage causing fire, and equipment grounding faults are all caused by leakage currents, typically ranging from 30mA to 3A, which are very small values. Traditional switches cannot provide protection, hence the use ofResidual Current Operated Protection devices.
Residual Current Protection Relay detects residual current through a residual current transformer, and under specified conditions, when the residual current reaches or exceeds the given value, it causes the contacts of one or more electrical output circuits of the electrical device to open or close.
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