The circuit relay coil with a long square symbol, if the relay has two coils, draw two parallel long box. At the same time in a box or long box beside the standard relay text symbols "J". Relay contacts said there are two kinds of methods: one is them painted directly on the long side of the box, this notation is relatively straightforward. Another kind is according to the need of circuit connection, the various contacts onto a separate control circuit, usually in the same relay contact and coil on the tagged near the same text symbols, to compile a number, and will contact to show the difference.There are three basic forms of relays:Type 1, or (H) coil is not energized the two contact is broken, after electrify, two contacts are closed. In a cooperative offended again said "H".2. Operation fault type (type D) coil is not energized the two contact is closed, two contact after the power supply is disconnected. Use hyphenation offended again said "D".3 · transformational type (z) is this contact group. There are three contacts, the contact group is in the middle is a moving contact, top and a static contact. Coil is not energized the moving contact and one of the static closed off contact with another coil after electrify, moving contact mobile, closes the original broken into, was closed off state, achieve the goal of transformation. The contact group called switch contact.With "turn" the word "pinyin", "2" said.
1, to understand the necessary conditions(1) the voltage of power supply control circuit, which can provide the maximum current;(2) controlled voltage and current in the circuit;(3) is accused of circuit need several groups, what forms of contact. When choosing relay, general control circuit of the power supply voltage can be taken as the basis for selection. Control circuit should be able to to provide enough working current relay, relay and is unstable.2 consult relevant data determine the conditions of use, please find the related information, find out the need to relay type and specification of the number. If existing relay in hand, can according to the data to check whether can use. Finally considering the size if appropriate.3. Pay attention to the volume of the appliance. If it is used for general use electrical appliances, besides considering the case volume, small relays main consideration circuit board installation layout. For small electrical appliances, such as toys, remote control device should choose microminiature relay products.
