The characteristics of the main technical parameters of relay
This paper introduces some basic knowledge about relay. Main relay characteristics, classification and some common technical parameters. Relay sensing portion is reflected in relay input, such as the electromagnetic coil of the relay, thermal relay double sheet metal. Execution section generates output such as the contact of the relay.
One, characteristics
Relay work is characterized with step type input / output characteristics, as shown in figure 1. In the relay to obtain an input signal X, irrespective of the signal amplitude vertebral much, as long as does not reach the action value X1, the relay does not operate, the output signal ( Y = 0 ( note Y0 ), the corresponding characteristic curve of 0 - point a. When the value of X to X1 immediately, relay action, the working point instantaneously from point a to point B will jump, Ymax output signal. Thereafter, if continue to increase the input signal, the output signal is Ymax constant. If the input signal is reduced, as long as the input signal X is not less than the release value Xr, output signal for the Ymax invariant, work points along the B, C change. But when X decreases to Xr, the relay is released, whereby the output signal is Y0, at this time, the relay operating point is moved along the B, C, D, 0, restitution.
Figure 1: electromagnetic relay input - output characteristic curve
In two, the main parameters of
Relay are rated parameters, motion parameters and setting parameters of three kinds of parameters.
1: setting parameters such as setting, repeatability, setting error, rated work, contact on-off contact ability, reliability, service life of machinery and electricity, the relay sensitivity.
2: action characteristic parameters such as the return coefficient ( or recovery coefficient ), reserve coefficient (also called safety coefficient ), control coefficient and response time, action time and the release time.
3: rated parameters such as the voltage and current, the pull-in voltage and current, the voltage and current release.
These technical parameters for the production of the relay assembly and commissioning work, action characteristic parameter is the most important, the remaining two kinds of parameters is the main user using the important parameters. The motion parameters, return coefficient and coefficient of reserve is the most important. Return coefficient ( or recovery coefficient ) for the release of Xr and Kr value of movement value ratio of X1, its value is less than 1, and is generally adjustable.
Kr = Xr / X1
Reserve coefficient ( also called safety coefficient ) Kc rated input Xw and action value ratio of X1, Kc = Xw / X1
When the input signal in a certain range, in order to ensure the reliable work of the relay, the input rating should be higher than the action value. Such as voltage relay rated working voltage of 220V, action voltage minimum 176V, whereby the voltage in the 176V relay output, its reserve coefficient Kc = 1. 25.
Three, classification
Usually, the relay has the following kinds of classification methods.
1 divided by scope of application
A: used in electric power system protective relay as the engine and transmission equipment, transformer protection.
B control relay: mainly used in electric drive system to control the process automation and provide some protection.
C communication relay: mainly used for telecommunication and remote control system.
2 according to the input signal character
A: voltage relay in the control circuit voltage reaches the set value action, to turn on or off a controlled circuit.
B current relay: in the control of the current in the circuit reaches the set value action, to turn on or off a controlled circuit.
C intermediate relay: principle still belongs to voltage relay, but it is generally in a electrical and controlled circuit to amplify the electrical control contact number and capacity of. Common JZ series of intermediate relay is the most commonly used to.
D time relay: such as drunk common JS series time relay. In get the motion signal, through the electromagnetic mechanism, mechanical or electronic circuit, a time delay before the contact action, to realize the control system of the time control.
E: principles of thermal relay is still current, but it is the use of the bimetallic strip is heated and bent to promote contact action, due to thermal bending is a time delay process, generally use it to realize overload protection. General JR series thermal overload relay is widely used.
F temperature relay: when the temperature reaches the set value when it moves, in order to achieve the overheating protection or temperature control.
G water level relay: when the water level in the container reaches the set value action, in order to achieve relief, liquid removal protection or water level control.
3 according to the working principle can be divided for electromagnetic relay, power relay, thermal relay, the transistor relay or integrated circuit relay.
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