What does the relay look like?
Third, the relay test 1, measuring contact resistance with a universal meter resistance file, measuring the normally closed contact and dynamic resistance, the resistance should be 0; and normally open contact and dynamic point of the resistance is infinite. Which can distinguish that is a normally closed contact, that is normally open contact. 2, the measured coil resistance can be used universal table R × 10Ω file measurement relay coil resistance, to determine whether the existence of the coil open phenomenon. 3, measure the pull-in voltage and pull the current to find adjustable power supply and ammeter, to the relay input a set of voltage, and in the power supply loop in the ammeter to monitor. Slowly increase the power supply voltage, hear the relay suction sound, write down the pull-in voltage and pull the current. For the sake of accuracy, you can try several times and find the average. 4, the measured release voltage and release current is also connected as described above test, when the relay occurs after the pull, and then gradually reduce the supply voltage, when you hear the relay once again release the sound, write down the voltage and current at this time, you can try Several times to achieve the average release voltage and release current. In general, the release voltage of the relay is about 10 to 50% of the pull-in voltage. If the release voltage is too small (less than 1/10 of the pull-in voltage), it can not be used normally, which poses a threat to the stability of the circuit , Work unreliable.
5, the choice of the relay 1. First understand the necessary conditions ① control circuit power supply voltage, can provide the maximum current; ② control circuit voltage and current; ③ charged circuit needs several groups, what form of contact. When using the relay, the general control circuit power supply voltage can be used as the basis for selection. The control circuit should be able to provide sufficient operating current to the relay, otherwise the relay pull is unstable. 2. Check the relevant information to determine the conditions of use, you can find the relevant information to find the necessary relay model and specification number. If there is a relay on hand, it can be used to check whether it can be used. Finally consider whether the size is appropriate. 3. Pay attention to the volume of the appliance. If used for general use of electrical appliances, in addition to considering the chassis volume, the small relay to consider the main layout of the circuit board installation. For small appliances, such as toys, remote control devices should be used ultra-small relay products.
Fourth, the relay electrical symbols and contact form Relay coil in the circuit with a rectangular symbol, if the relay has two coils, draw two parallel rectangular box. At the same time in the box or rectangular box marked with the relay symbol "J". There are two ways to represent the relay: one is to draw them directly on the side of the box, this representation is more intuitive. The other is in accordance with the needs of the circuit connection, the various contacts were drawn to the respective control circuit, usually in the same relay contacts and coils were marked with the same text symbols, and contact group number, To show the difference. Relay contacts have three basic forms: 1. Dynamic type (H type) coil is not energized when the two contacts are open, power, the two contacts on the closed. To the word "H". 2. The dynamic contact (D type) coil is not energized when the two contacts are closed, after the two contacts on the power off. With the word "D" of the word. 3. Conversion type (Z type) This is the contact type. This contact group has three contacts, that is, the middle is moving contact, up and down a static contact. When the coil is not energized, the movable contact and one of the static contacts are disconnected and the other is closed. After the coil is energized, the movable contact moves, so that the original opening is closed and the original closed state is closed. purpose. Such a contact group is called a changeover contact. Use the word "z" for the word "z".
Second, the main technical parameters of the relay 1, rated operating voltage is the normal operation of the relay coil voltage required. Depending on the type of relay, it can be an AC voltage or a DC voltage. 2, DC resistance refers to the relay in the coil DC resistance, can be measured through the universal table. 3, pull the current refers to the relay can produce the minimum action of the suction action. In normal use, the given current must be slightly larger than the pull-in current, so that the relay can work stably. And the working voltage applied to the coil, generally do not exceed 1.5 times the rated working voltage, otherwise it will produce a larger current and the coil burned. 4, the release current is the relay to release the action of the maximum current. When the relay pull-up state of the current is reduced to a certain extent, the relay will return to the state without power release. At this time the current is much smaller than the pull-in current. 5, contact switching voltage and current is the allowable load of the relay voltage and current. It determines the relay can control the size of the voltage and current, the use can not exceed this value, otherwise it is easy to damage the relay contacts.
