Commonly used solid state relays include HS, GTJ, JGW, KW, G3FD-×03SN, GZ1-L, G22-L, SZT036, JGJ, JGZ and other products. When selecting a solid state relay, first consider the type of solid state relay and adjust it with a load (the main technical guidelines include additional input voltage, input current, additional output voltage, output current, surge current, output conduction voltage drop, output leakage current, Operating frequency). The selected solid-state relay should have a certain power margin, and its output voltage and output current should be higher than 1 times the voltage and current of the power supply of the controlled circuit. If the controlled circuit is an electrical load, the output voltage and output current of the solid-state relay should be more than 2 times higher than the power supply voltage and current of the controlled circuit.
(1) The tube voltage drop after the conduction is relatively large, up to 1~2V. Regarding high-power solid state relays, the power consumption and heat generation after conduction are also large. The heat dissipation conditions (such as adding a radiator, Fan cooling, etc.).
(2) The leakage current from microamperes to several milliamperes can still be rare after it is turned off, and the electrical isolation of the aspiration cannot be completed. Regarding some low-power loads (such as base relays, touch device coils, electromagnets, etc.), solid-state relays with a leakage current less than 1mA should be selected, otherwise it will cause malfunctions (3) have greater sensitivity to overloads. It is necessary to use active fuses or RC damping circuits for overload maintenance.
(4) SSR is a current-driven type. When driving the logic circuit, low-level output should be used as much as possible to drive, so as to ensure that there is a satisfactory load and the lowest possible zero level.
(5) The input terminals of multiple SSRs can be used in series and parallel, but it should be satisfied that the parallel drive current is greater than the sum of the input currents of multiple SSRs, and the series drive voltage is greater than the sum of multiple turn-on voltages (calculated at 4V).
(6) Communication SSR is suitable for 50Hz or 60Hz power frequency power grid, and it is not suitable to be applied to the occasions where the weight of higher harmonics is heavy. For example, when there are multiple sets of load requirements at the output of the inverter to switch separately, if the SSR is used as the switch, the higher harmonics may make it impossible to shut down reliably, and the higher harmonics may also cause the RC absorption circuit inside the SSR to overheat. And burst.
