Even small surges or peak voltages can ultimately destroy or affect the performance of expensive electronic devices such as computers, telephones, faxes, televisions, audio/visual equipment, and other home appliances and tools. The widespread use of computer chips is increasingly requiring surge protection because these chips are often very sensitive to voltage fluctuations. Therefore, it is necessary to install a power surge protector. First, the choice of flow rate 1) Example of building lightning protection zone and equipotential bonding Every object in the LPZOA area may be subjected to direct lightning strikes. Therefore, each object may conduct lightning current, and the electromagnetic field in this area is not attenuated. All objects in the LPZOB area are unlikely to be subjected to direct lightning strikes, but the electromagnetic fields in this area are not attenuated. It is impossible for each object in LPZ1 to be directly struck by lightning. The current flowing to each conductor is further reduced than the LPZOB zone, and the electromagnetic field in this zone may also be attenuated, depending on the shielding measures. LPZ2 (subsequent lightning protection zone) If it is necessary to further reduce the current and/or electromagnetic field, it should be introduced into the subsequent lightning protection zone. The subsequent lightning protection zone should be selected according to the environment required by the system to be protected. 2) Flow capacity selection of building power system It should be selected according to the lightning protection level requirements of buildings specified in the national standard GB50057-94 "Code for lightning protection design of buildings". The LPZOA area uses a 10/350μs waveform (the main function is to discharge the energy of the lightning strike) Second, the choice of the maximum continuous working voltage value (Uc) The maximum continuous operating voltage (Uc) of zinc oxide varistor lightning arresters (such as TPSB65, TPSC40) is a key parameter related to the operational stability of the lightning arrester. When selecting the maximum continuous operating voltage value of the lightning arrester, in addition to complying with the relevant standards, the normal fluctuations that may occur in the installation of the power grid and the highest possible continuous fault voltage may be considered. According to IEC61643-2, in the TT AC power supply system, the highest continuous fault voltage of the phase-to-ground line may reach 1.5 times the nominal voltage (UN) (AC voltage 220Urms), which is likely to reach 330Urms. Therefore, in places where the current is unstable, it is recommended to select the module with the maximum continuous operating voltage (Uc) of the TOWE power surge protector of 385 Urms. In a DC system, there is no uniform ratio of the maximum continuous operating voltage (Uc) to the normal operating voltage (Un), but empirically the ratio is typically between 1.5 and 2 times. Third, the choice of residual pressure (Ures) Simply consider the lower the residual voltage of the lightning arrester, the better, not comprehensive, and easy to cause misleading. First, the residual voltage values ​​of different products must be marked with the magnitude and waveform of the test current in order to have a common basis for comparison. The residual current is typically recorded at 20KA (8/20 μs) for comparison. Secondly, the lower the residual voltage is used for the varistor lightning arrester, it usually means that the maximum continuous operating voltage (Uc) is lower. Again, over-emphasis on low residual voltage is a price that is required to reduce the maximum sustained operating voltage (Uc). The consequence is that in areas with unstable mains, the lightning arrester is easily damaged by excessive overvoltage for a long time. In fact, for varistor type lightning arresters, the maximum continuous working voltage (Uc) and residual pressure, just like the two sides of the balance, can not focus on either side. According to past experience, the residual voltage is below 2KV (20KA8/20μs), which can provide sufficient protection for user equipment. Fourth, the choice of alarm function In order to monitor the operation of the arrester, when the lightning arrester is damaged, the user should know and replace the damaged lightning protection module in time. In order to achieve real-time monitoring in different application environments, it is necessary to select an alarm device that is suitable for a specific environment. There are three options for the alarm device of the TOWE lightning protection device, which can be used for different requirements of different environments. Sound and light alarm device-AS, suitable for use in a manned environment; remote signal alarm device-S, suitable for unattended environments; Remote signal with voltage detection and alarm device - additional function of lightning protection box, suitable for unattended environment, and can monitor the power supply for power failure and phase loss. 5. Design backup protection air switch for protection circuit when the lightning arrester fails For electrical safety reasons, any electrical component that is mounted in parallel relative to or in the opposite direction of the power supply must be equipped with a short circuit protection device, such as an air switch or fuse, in front of the electrical component to prevent a faulty short circuit. 6. In the case of poor power supply environment, circuit design should be specially considered - 3+1 structure design In areas with poor power supply environments or areas where power supply is unclear, users are advised to use 3+1 lightning arresters. The 3+1 lightning arrester refers to the installation of a varistor lightning protection module between the phase line and the neutral line, and a discharge gap lightning protection module is installed between the neutral line and the ground line. This kind of protection structure has a more reliable advantage than installing a lightning protection module between the traditional phase line and the ground line. Under the TT grid, the lightning arrester is connected between the mains phase line and the ground line. The loop impedance is mainly the grounding resistance. The grounding resistance varies greatly in different environments. In some places, the grounding resistance is high, not common. When the power grid fails, for example, the neutral line is disconnected or the zero point drifts, the mains fault voltage is formed for a long time higher than the maximum continuous working voltage (Uc) of the lightning arrester, and the lightning arrester is damaged to generate the loop fault current. In the case of a high grounding resistance value or a poor ground contact, the short-circuit current flowing through the lightning arrester is too small to allow the front-end fuse to trip, causing the lightning arrester to continue to overcurrent and cause damage. The 3+1 structure lightning arrester using the NPE module in the case of grid failure, even if the grounding resistance is high or the grounding wire is in poor contact, because the lightning arrester is connected between the phase line and the neutral line, and the mains phase line and Neutral loop impedance, mainly power supply transformer and power supply cable, the impedance is very low, so the fault current is very large, the current flowing through the lightning arrester can make the front-end fuse (open) trip, so that the lightning arrester is isolated from the power grid. Make sure the circuit is safe.
Draw-wire sensors of the wire sensor series measure with high linearity across the entire measuring range and are used for distance and position measurements of 100mm up to 20,000mm. Draw-wire sensors from LANDER are ideal for integration and subsequent assembly in serial OEM applications, e.g., in medical devices, lifts, conveyors and automotive engineering.
Linear Encoder,Digital Linear Encoder,Draw Wire Sensor,1500Mm Linear Encoder Jilin Lander Intelligent Technology Co., Ltd , https://www.jllandertech.com