The working principle of relay is peripheral (overhead light) control, that is, the traffic lights change automatically occasionally?

First, the working principle and characteristics of relay

Relay is an electronic control device, which has a control system (also called input loop) and a controlled system (also called output loop). Usually used in automatic control circuits, it is actually an "automatic switch" that controls a larger current with a smaller current. Therefore, it plays the role of automatic adjustment, safety protection and conversion circuit in the circuit.

1, working principle and characteristics of electromagnetic relay

Electromagnetic relay generally consists of iron core, coil, armature and contact reed. As long as a certain voltage is applied to both ends of the coil, a certain current will flow in the coil, thus generating an electromagnetic effect. Under the attraction of electromagnetic force, the armature overcomes the pulling force of the return spring and attracts the iron core, thus driving the moving contact of the armature to attract the stationary contact (normally open contact). When the coil is disconnected, the electromagnetic attraction disappears, and the armature will return to its original position under the reaction of the spring, so that the moving contact and the original static contact (normally closed contact) attract each other. In this way, it is attracted and released, so as to achieve the purpose of making and breaking the circuit. For the normally open contacts and normally closed contacts of relays, we can distinguish them as follows: the static contacts that are disconnected when the relay coil is not energized are called "normally open contacts"; Static contacts in the on state are called "normally closed contacts".

2. Working principle and characteristics of hot reed relay.

Thermal reed relay is a new type of thermal switch which uses thermomagnetic materials to detect and control temperature. It consists of a temperature-sensing magnetic ring, a constant magnetic ring, a reed switch, a heat-conducting mounting piece, a plastic substrate and other accessories. The hot spring relay does not need coil excitation, but the magnetic force generated by the constant magnetic ring drives the switch to act. Whether the constant magnetic ring can provide magnetic force to the reed switch is determined by the temperature control characteristics of the temperature sensing magnetic ring.

3. Working principle and characteristics of solid state relay (SSR)

Solid-state relay is a four-terminal device, two of which are input terminals, the other two are output terminals, and an isolation device is used in the middle to realize the electrical isolation of input and output.

According to the type of load power supply, solid state relays can be divided into AC type and DC type. According to the switch type, it can be divided into normally open type and normally closed type. According to the isolation type, it can be divided into hybrid type, transformer isolation type and photoelectric isolation type, with photoelectric isolation type being the most. .

Second, the relay main product technical parameters

1, rated working voltage

Refers to the voltage required by the coil when the relay works normally. Depending on the model of the relay, it can be AC voltage or DC voltage.

2. DC resistance

Refers to the DC resistance of the coil in the relay, which can be measured by multimeter.

3. Pull-in current

Refers to the minimum current that relay can produce pull-in action. In normal use, the given current must be slightly larger than the pull-in current before the relay can work stably. In general, the working voltage applied to the coil should not exceed 1.5 times of the rated working voltage, otherwise a large current will be generated and the coil will be burned.

4. Discharge current

Refers to the maximum current that the relay produces release action. When the current in the pull-in state of the relay decreases to a certain extent, the relay will return to the non-energized release state. At this time, the current is much less than the pull-in current.

5, contact switching voltage and current

Refers to the voltage and current allowed by the relay to the load. It determines that the relay can control the voltage and current, and cannot exceed this value when it is used, otherwise it will easily damage the contacts of the relay.

If you want to control the peripheral sunshade lights, you should use relays and time relays as control circuits!