Accurate conductor cross-sections are of great importance when selecting protective equipment during the installation of grounding systems. For the tripping time of the overcurrent protection relays, it is absolutely necessary to check the appropriate cross-sections. These studies are performed by loop impedance measurements. The loop impedance is a source impedance measured between the protective earth and the line. If the phase conductor short-circuits the protective earth conductor, the predicted earth fault current that can potentially flow can also be detected. Earth resistance measurements can also be made by loop impedance method. For earth resistance loop test, three-wire connection is made as phase, neutral and ground. The resistances of the test leads are reset before the measurement. TN systems use overcurrent arrangements for indirect touch protection; it is necessary to check whether the selected conductor cross-sections correspond to the current required for each tripping time. For indirect contact protection, the loop impedance between the main conductor and the protection conductor and between the main conductor and the PEN conductor must be determined. Or if the installation is protected by overcurrent protection elements, the loop loop impedance Z LOOP must be measured. The impedance value between the phase and the PEN conductor must be as small as possible in order for the device used to open the circuit within the specified time interval due to the fault current generated during the fault. This value can be obtained by measuring with measuring devices. Since the voltage swings may occur during the measurement, a large number of measurements should be averaged. In general, the loop impedances are made at room temperatures or at ambient temperatures depending on the season. The loop impedance measurement must be made from the furthest point of a current circuit.
The Regulation on Electrical Indoor Facilities, which entered into force in 2004, includes provisions for the establishment and transmission of electrical indoor facilities. The principles of this regulation must be applied in the new facilities, if the existing facilities are completely changed, if the existing facilities are clearly seen as a danger of death, injury and fire or if the existing facility creates a danger for the other facilities in the environment.Health and Safety Measures to be Taken in the Workplace Building and Extensions published in The regulation also specifies the minimum health and safety conditions that should be included in the premises and additions to the workplace.
Pursuant to these legal regulations, the project work of the electrical installation, installation, selection of materials and protective devices must be appropriate to the voltage and ambient conditions to be used. At the same time, maintenance, repair, control and operation principles should be made within the framework of these legal regulations. According to these regulations, employers have to have electrical tests and controls regularly and keep control reports.
Our company conducts loop - loop impedance measurements in accordance with the relevant legal regulations, standards and test methods published by domestic and foreign organizations within the framework of electrical safety inspections. The following standards are considered in these studies:
- TS HD 60364-4-43 Electrical installation in buildings - Part 4: Protection for safety - Part 43: Overcurrent protection
- TS HD 60364-4-44 ... Part 44: Protection against overvoltages Protection of the low-voltage installation against faults between high-voltage systems and earth
