Relays are devices that are often encountered in our automatic control circuits. Of course, the current automatic control system can use some electronic switches, such as field effect transistors, triodes, and optocouplers, because their out ability is small. Today, China PCB manufacturer SysPCB will introduce the classification of relay.
Relays can be classified according to their working methods, size, load power, and relay packaging.
The internal structure is shown in the figure:
The second type is solid state relay, is characterized by: a relay with isolated input and output that uses electronic components to perform its functions without mechanical moving components, and its appearance is shown in the following figure:
The internal block diagram is shown in the figure:
The third type: temperature relay, its working characteristics are: when the outside temperature reaches the set threshold, the relay works.
The fourth type: reed relay, its working characteristics are: a relay that acts when the outside temperature reaches a given value.
The fifth type: time relay, when the input signal is added or removed, the output part needs to be delayed or limited to a specified time before closing or disconnecting its controlled circuit relay, its appearance is shown in the following figure:
The sixth type: high-frequency relays, which are used to switch high-frequency, radio frequency lines with minimum loss of relays.
The seventh type, polarized relay, is a relay that operates by the combined action of the polarized magnetic field and the magnetic field generated by the control current through the control coil. The direction of action of the relay depends on the direction of the current flowing in the control coil.
Other types of relays: such as photorelays, acoustic relays, thermal relays, instrumentation relays, Hall effect relays, differential relays, etc.
(1) Miniature relays: relays with the longest side dimension not greater than 10 mm.
(2) Ultra-small miniature relays: relays with the longest side dimension greater than 10 mm, but not greater than 25 mm.
(3) Small miniature relays: relays with the longest side dimension greater than 25 mm, but not greater than 50 mm.
Note: For hermetic or enclosed relays, the external dimension is the largest dimension of the relay body in three mutually perpendicular directions, excluding the dimensions of mounting parts, lead-out ends, pressure ribs, pressure edges, flanges and sealing solder joints.
(2) Weak power relay: when the open-circuit voltage of the contact is DC 28V, the current is 0.5A, 1A relay.
(3) Medium power relay: when the open-circuit voltage of the contact is DC 28V, the current is 2A and 5A.
(4) High-power relay: When the open-circuit voltage of the contact is DC 28V, the current is 10A, 15A, 20A, 25A, 40A...
(2) Enclosed relay: a relay that is protected by sealing (non-sealing) such as contacts and coils with a cover.
(3) Open relays: relays that do not use protective covers to protect electric shocks and coils.
The two most commonly used relays in electronic production are electromagnetic relays and reed relays.