## Wednesday, December 29, 2010

### Weak current College】 【small DC relay parameter】.

<br> <br> 1. rated operating voltage <br> Refers to the relay coil Typ desired voltage. According to the model, the relay can be AC voltage or DC voltage. <br> <br> 2, DC resistance <br .> <br> Refers to the relay coil of DC resistance, through the universal table measurements. <br> <br> 3. closing current <br> <br> Refers to the relays can produce the smallest suction action. In normal use, .given current must be slightly larger than the pull-in current so that relay to stable work. For coil the working voltage, generally do not exceed the rated voltage of 1.5 times, otherwise it will produce a larger current and coil burn. <br> .<br> 4, discharge current <br> <br> Refers to generating release action relay maximum current. When the status of current pick-up decreases to a certain extent, the relay will return to the powered release status. When the current far .less than closing current. <br> <br> 5. touch point switching voltage and current <br> <br> Refers to relay allows load voltage and current. It determines the relays to control the size of the voltage and current, and must .not exceed this value, otherwise it is very easy to damage the contacts of relays. <br> <br> Third, the relay test <br> <br> 1. measuring contact resistance <br> <br> Universal table of resistance, .measuring close regular contact and fixed point resistance, its resistance value should be 0, (with more accurate ways to measure contact resistance in 100 mohm); and normally open contact and fixed points of resistance to infinity. It can thus be distinguished from that is .normally closed contact that is normally open contact. <br> <br> 2. measuring coil resistance <br> <br> Available universal table R × 10 Ω stall resistance measuring relays coils to determine the existence of an open coil. <br> .<br> 3. measuring pull-in voltage and current pick-up <br> <br> Find a adjustable voltage-stabilized source | voltage regulator and ampere meter, to enter a set voltage relays, and power supply circuit conspiracy into the ammeter .. Slowly increase the power supply voltage, hear the sound of the pick-up, note the pull-in pull-in voltage and current. For the sake of accuracy, you can try several times and averages. <br> <br> 4 .. measure the voltage and current release release <br> <br> It is like the above then connection test, when the relay event of pick-up, and gradually reduce the supply voltage, when hear the relay again when you release the voice, .write down the voltage and current, but also try to acquire more than a few times on average release voltage and current release. In General, the relay release voltage of about pull-in voltage 10-50%, if you release the voltage is too .small (less than 1 / 10 of pull-in voltage), you cannot normally use, this will pose a threat to the stability of the circuit, is not reliable. <br> <br> Fourth, the relay of symbols and contact form .<br> <br> Relay coil circuit with a long box notation, if relay has two coils, draw two long boxes side by side. At the same time in a long box or long box next to the marked text symbols of relay "J .". Relay contacts have two methods: one to draw them directly in the long side of the box, this notation is more intuitive. Another way is to follow the circuit connection, the contact points are drawn to the respective control circuit, usually in the .same relay contacts and coils respectively noted on the same text symbols, and the number of contact group, to distinguish the two. <br> <br> Relay contacts there are three basic forms: <br> <br> 1. fixed-type .(h) coil not powered two-contact is broken, after power-on, the two contacts are closed. To close the word Ruby-prefix "H". <br> <br> 2. fixed broken type (d type) coil .not power on when two contacts are closed, after power disconnect two contacts. Using hyphenation of Ruby-prefix "D". <br> <br> 3. the conversion type (Z)-this is the contact group. The contact group has .a total of three contact points, ie the middle is moving up and down all the contacts, the contacts of a static. Coil not power on when moving contacts and one of the static contact disconnect and another closed, coil energized, dynamic contact is moved .so that the original broken into closed, the original closed into the off State, reach the purpose of the conversion. This contact group called convert contacts. Use the "go" in the words of Ruby-prefix "z" represents. <br> .<br> Selection of five, relays <br> <br> 1. to understand the necessary conditions <br> <br> ① voltage control circuit of a power supply, and can provide maximum current; <br> <br> ② is .control circuit voltage and current; <br> <br> ③ charged circuit takes several groups, what forms of contact. Choose relay, general control circuits power supply voltage can be used as the basis for selection. Control circuit should be able to relay to .provide adequate operating current, otherwise the pick-up is unstable. <br> <br> 2. access to the relevant information to determine the conditions of use, you can find relevant information, identify the needs of the model and specifications of relay. .If you already have on hand, which narrows the data relay check whether you can use. Finally, consider the size is appropriate. <br> <br> 3. takes note of the volume of the apparatus. If it is used for General Electric ., apart from the chassis volume, small relay circuit mounted a major consideration. For small appliances, such as toys, remote control unit you should use the product mini relay. <br> <br> <br> <br>.