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| Product name : Electrical relays |
| Item : AEC_ Electrical relays |
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Electrical relays
Relay is an electrical control device, when the changes in the input (incentive amount) to achieve the specified requirements, the amount charged to a predetermined step change in the electrical output circuit make an electrical . It has a control system (also known as the input circuit) and control system (also known as the output circuit) the interaction between. Usually applied to the automation of the control circuit, it is actually a small current to control a large current operation of the kind of "automatic switch. Therefore automatically adjusted in the circuit plays the role of the security protection, and conversion circuit.
Major categories
1. Classified by the working principle or structural features of the relay 1) the electromagnetic relay: the use of the internal circuit of the input circuit to the electromagnet core relay (Figure 4)
The work with the suction effect generated between the armature and an electrical relay. 2) Solid State Relay: refers to the electronic components to fulfill its function without mechanical moving structures, input and output isolation relays. 3) temperature relay: the relay when the outside temperature reaches a given value and sometimes action. 4) reed relay: Using sealed within the tube, having the dual role of electric shock the reed and armature magnetic circuit reed action to open the line of the closed or changeover relay 5) time relay: When added to or removed from The input signal, the output part of the need to delay or time-limited to a predetermined time before closure or disconnect it from the charged line relays. 6) high-frequency relay: for switching high-frequency RF circuit relay with minimum loss. 7) The polarized relay: the combined effect of the magnetic field generated by the polarizing magnetic field and the control current through the control coil and the relay action. The direction of action of the relay depends on the control direction of the current flowing through the coil of the. 8) other types of relays: light relay, sound relay, thermal relay, meter relay, Hall effect relays, differential relays.
Relay Dimensions Category 1) miniature relay 2) ultra-small micro relay 3) small and micro relays Note: Dimensions sealed or closed relay relay body the maximum size of the mutually perpendicular directions, not including the mounting member, terminal, beading, beading, flanging and sealing the size of the solder joints. Classified according to the load of the relay 1) micro-power relay 2) weak power relay 3) Power Relay 4) power relay, relay protection features of Category 1) Seal relay 2) closed relay 3) open relay 5 relay 1) electromagnetic type 2) Induction 3) can be classified according to the action principle the rectifier type 4) E-5) digital type 6 can be classified according to the physical quantity of the reaction 1) frequency relay current relay 2) voltage relay 3) directional power relay 4) impedance relay 5) 6) gas (gas) relay, in accordance with relay protection circuit can be categorized as 1) Start relay time relay 2) measuring relays 3) 4) intermediate relay 5) signal relay 6) export relay
Major role relay automatically switching element having an isolation function, widely used in remote telemetry relay (Fig. 3)
Communications, automation, mechatronics, and power electronic equipment, is one of the most important control elements. The relay generally have to reflect a certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, velocity, light, etc.) the sensing mechanism (input portion); circuit accused "pass" , "off" the implementation of the control mechanism (output portion); coupled isolation between the input section and output section of the relay, on the input amount, function processing, and the output portion for driving the intermediate bodies (driving portion) . As a control element, summed up, the relay follows several roles: 1) to expand control: for example, a multi-contact relay control signal reaches a certain value, according to the different forms of the contact group, and Changes breaking, connect multiple circuit. 2) amplification: for example, sensitive relays, the intermediate relay, etc., a large power circuit can be controlled with a very small control amount. 3) signal: for example, when a plurality of control signals according to the provisions in the form of input multi-winding relay, after a relatively comprehensive, to achieve the control effect. 4) automatic, remote control and monitoring: For example, the automatic device relays together with other appliances, you can make up the program control circuit, in order to achieve the automated operation.
The relay contacts are three basic forms: 1, moving together (normally open) (H-type) coil is not energized when the contact is broken, energized, two contacts closed. Together word phonetic prefix "H". 2, move off type (normally closed) (D type) coil not energized when the two contacts are closed, the energized two contacts disconnect. With hyphenation Pinyin prefix "D". Conversion (Z type) contact group. This contact group has a total of three contacts in the middle and moving contact, upper and lower stationary contact. Coil is not energized, the movable contact and one stationary contact disconnected and another closed, the coil is energized, the movable contact is moved, so that the original off into closed, the original closed to the open state, reach conversion purposes. This contact group called changeover contacts. Phonetic head with the word "turn" "z" indicates.
Common types
1, the over current relay overcurrent relay, referred to CO is from current exceeding its set value, the relay action, do use of the system circuit and overload protection, the most commonly used is induction-type overcurrent relay electrical electromagnet with aluminum or copper rotating disk relative to rely on the principle of electromagnetic induction rotating disk rotation, in order to achieve the protective effect. Action Principle: induction-type over current relay is the use of the side of the current transformer secondary current, a magnetic field is generated in the relay in order to facilitate the rotating disk, but the current flowing through the current landmark set plate must be greater than the current value in order to rotation. 2, over-voltage relay overvoltage relay, referred to as OV, its main purpose is that when the abnormal voltage of the system is increased to more than 120% of the rated, over-voltage relay action and the circuit breaker tripped the protection of electrical equipment from damage, the structure and operation principle of inductive overvoltage relay and overcurrent relay similar, only the main coil. 3, the under voltage relay undervoltage relay, referred UV its structure and over-voltage relay is the same, the difference is that the internal contacts and when the applied voltage when the turntable will immediately turn. 4, grounding overvoltage relay ground overvoltage relay (OVG) or ground alarm relay referred GR, constructed with over-voltage relay, using the three-phase three-wire grounding system, connected to the opening triangular grounded grounding transformer for detecting the zero-phase voltage. 5, ground overcurrent relay ground overcurrent relay (GCR) is a high-voltage line to ground protection relay.
The main purposes: 1) high resistance grounding system ground overcurrent protection; 2) generator stator winding ground fault protection; 3) split-phase generator layer short circuit protection; 4) grounding transformer overheating protection. 6, the selective grounding relays selective grounding relay, acronym SG, also known as directional ground relay, referred to as the DG for the protective effect of distribution lines used in ungrounded systems, overhead lines and cable systems can use . Selective ground relay: zero-phase-sequence current detection by ground voltage transformer such as the case of the line to ground, selective ground relay can indeed that the fault line alarm occurs, and in accordance with its need to select the fault line off open, and continue to the normal line power transmission. 7, phase failure relay phase failure relay, referred to as the OPR, or phase protection relay, referred to as the PHR, the three-phase line, when the power supply side there is a glimmer of open circuit caused by single-phase, if not immediately cut off the line, and burned the motor running single phase. 8, the percentage differential relay percentage differential relay, referred to the RDR, is applications do transformer AC motor, alternator, differential protection, overcurrent protection relay, conventional external fault when an abnormal current flows through the protective device, if the transformer and a secondary side current occurs imbalance or inconsistency occurs on the current transformer characteristics, in these circumstances, this phenomenon will be extending multiple malfunction leaving relays.
Selection conditions
1, first understand the necessary conditions 1) a control circuit power supply voltage, the maximum current that can be provided; 2) of the control circuit voltage and current; 3) The the charged circuit requires several groups, what form the contacts. The selection of relays, the general control of the supply voltage of the circuit can be used as the basis for selection of. Control circuit to provide enough current to give the relay, or relay together is unstable. 2, check out the information to determine the conditions of use, you can find relevant information identify the number of models and specifications of the relay. Based on the information on hand already relay, check whether you can take advantage of. Finally, consider the size is appropriate. 3, note that the volume of the appliance. If used for general electrical appliances, in addition to considering the chassis volume, small relay mainly consider the layout of the circuit board mounting. For small appliances, toys, remote control device should be used to a small relay products.
Model logo
General domestic relay type designation consists of four parts: the first part + + Part III + Part IV. The first part of the relay model relay the Lord calls the type represented by the letters. JU - JR - small power relay JZ - power relays JQ - power relay JC - magnetic-electric relay thermal relay or temperature relay JT - Special Following electrical pulse relay JM - JS - time relay JAG - The second part of the reed relay relay models with the letter represents the shape characteristics of the relay. W - Micro X - Small C - the third part of the ultra-small relay model number indicates the serial number of the product. With a digital product serial relay Model Part IV letter said protective features. The F - closed M - Sealed For example: JRX-13F (closed small power small relay). JR - small power relay X - Small
No. 1, the use of environmental conditions by the use of environmental selection mainly refers to the temperature (maximum and minimum), humidity (generally 40 ° C under relative humidity), low pressure (to use the time to consider the height of 1000 meters below), vibration and shock. In addition, there package installation method, Dimensions and insulation requirements. Different materials and structures, different relays withstand environmental and mechanical conditions, the environment more than the product standard specifies the mechanical conditions, it is possible to damage the relay may be the whole environmental and mechanical conditions or high-level conditions chosen . Sensitive to electromagnetic interference or radio frequency interference device around, it is best not to use the AC excitation of the relay. Choice the DC relay should I use with coil transient suppression circuit products. Providing incentives and relatively sensitive to spikes with a solid-state device or circuit should select transient suppression circuitry.
2, according to the different decides that the relay type of the input signal by the input signal power, temperature, time, an optical signal to determine the choice of electromagnetic, temperature, time, photoelectric relay, this is no problem. Otherwise specified voltage, current relay selection. If the whole supplied to the relay coil is constant current should be used in the current relay, the constant-voltage value is selected voltage relay.
3, the input parameters selected closely associated with the user input is the coil working voltage (or current), while the absorption in voltage (or current) is a The relay manufacturer control relay sensitivity and their judgment and assessment parameters. The user is concerned, it is just a working lower limit parameter values. The control safety factor is the operating voltage (current) / pull-in voltage (current) relay pull value is unreliable, unsafe elevated ambient temperature or in a vibration under impact conditions, the the relay does not work reliably. The design of the machine, not the no-load voltage as the the relay working voltage basis, especially as a load to calculate the actual voltage, source resistance, especially when large coil access should be. When the transistor as a switching element control coil on and off, transistors must switch state on the the 6VDC following operating voltage relay terms shall be deducted from the transistor saturation voltage. Of course, not the work value was as high as possible, exceed the rated value is too high will increase the impact of the armature wear, increased contact bounce times shorter electrical life, general 1.5 times the value of the aggregate value of suction, work values error is generally ± 10%. 4, according to load conditions to select the type and capacity of the relay contacts domestic and international long-term practice proved that about 70% of the fault occurred in the contacts, This indicates the proper selection and use of the relay contacts, is very important. The contact combination form and number of the contact group should be determined according charged with the actual situation of the loop. Front contact in the contact group and changeover contact group to move together, due to the large amount of compensation after the jump fewer and contact ablation contacts back is turned, its load capacity and the contact reliability than off contact off contact on the contact group of the group and the conversion to be high, the whole line by appropriate adjustment of the contact position, as much as possible with the front contact. Parameters are determined according to the nature of the load size and load (resistive, inductive, capacitive, Lamp load and motor load) is very important. It is incorrect to think that contact must be better than the large and reliable switching load switch load small, general relay to switch the load at the rated voltage, current greater than 100mA, less than 75% of the rated current best. Current is less than 100mA makes contacts coke increased, decreased reliability, it is referred to as the test current of 100mA, professional standards at home and abroad on the relay plant process conditions and the level of assessment content. General-purpose relays do not have low switching capacity for the relay switch 50mV, 50μA load order, the user must be marked, please be necessary the relay manufacturing plant to assist selection. Relay contacts rated load life refers to the rated voltage, current, load for resistive action times when the rated voltage is exceeded, the reference to the contact load curve selection. When the change of the nature of the load, the contact load ability to change with.
The rated working voltage: refers to the voltage required by the relay normally work coil,
Schematic (13) that is the control of the control voltage of the circuit. Depending on the relay model, which may be an AC voltage may be a DC voltage. DC resistance: refers to the DC resistance of the relay coil can be measured by multimeter. The current Pick: Relay able to generate a minimum current pull action. In normal use, given the current must be slightly larger than the pull-in current, so that the relay can work steadily. While for the coil plus the working voltage, usually do not exceed 1.5 times the rated working voltage, otherwise it will generate a large current to the coil burnt. Release current: Relay generate maximum current release action. When the relay is energized state current is reduced to a certain extent, the relay will revert to the not released state power. When the current is much smaller than the pull-in current. Contact switching voltage and current: refers to the the relay allows load voltage and current. It determines the relay can control the size of the voltage and current can not exceed this value, it will be very easy to damage the relay contacts.
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