How to measure the quality of solid-state relay with digital multimeter
When we detect the quality of solid state relay, it is generally impossible to detect it with multimeter. The correct detection method should be like this.
First of all, after the appearance inspection is in good condition, we can connect an adjustable DC voltage source from 3V to 32V to its input control terminal. At this time, we should observe whether the LED can emit light normally. At this time, we should pay attention to that the output terminal is not connected to a load or a power supply.
The second step is to operate as follows: at this time, we can use the pointer multimeter RX1K to detect the output resistance. If the input control voltage UI is less than UI<2.7V, the resistance indicated by the multimeter should be infinite, in other words, the output of the solid state relay should be non-conductive; We continue to increase the voltage. When the voltage increases to 3V, the resistance value of the multimeter is generally lower than 10 ohms, indicating that the output terminal of the solid state relay has been turned on.
Finally, the third step: after the first two tests are normal, we can connect the load and power supply. When the input voltage is 0V, the load will not work. When the input terminal voltage is increased to about 5V, the load can work. At this time, it shows that the solid state relay is in good condition, otherwise the solid state relay is faulty and needs to be repaired.
How to measure the quality of solid state relay
On the shell of AC solid state relay, the INPUT terminals are generally marked with the words "+","-"and "input", while the output terminals are not positive or negative, but some devices are marked with the words "LOAD". For DC solid state relays, the INput and OUTput terminals are generally marked with "+"and "-",and some devices are also marked with the words "in" and "out" to show the difference.
When the digital multimeter is used to distinguish the input terminal and the input terminal, the diode file can be used to test the four pins in the forward and reverse directions respectively, in which the voltage between a pair of pins can be measured to conform to the law of forward conduction and reverse cutoff, that is, "1.3~1.6V" is displayed in the forward measurement, and the overflow symbol "1" is displayed in the reverse test. According to this, it can be judged that these two pins are input terminals, and in the forward measurement, a measurement of "1.3~1.6V" is displayed, and the red stylus is connected to the positive electrode, while the black stylus is connected to the negative electrode. For DC solid-state relay, after finding the input terminal, the anode and cathode of the output terminal are generally opposite to each other horizontally. It should be pointed out that some DC solid-state relays have protection diodes at the output end, and the positive electrode of the protection tube is connected with the negative electrode of the solid-state diode, and the negative electrode of the protection tube is connected with the positive electrode of the solid-state relay. Pay attention to the correct distinction when testing.
