1. According to the number of channels:

Divided into single channel solid-state relays and multi-channel solid-state relays.

A single channel solid-state relay has one control input and one output channel, suitable for switch control of a single signal; Multi channel solid-state relays have multiple control input and output channels, which can simultaneously control the switching states of multiple signals.

2. According to the type of load:

Divided into DC Solid State Relays (DC-SSR) and AC Solid State Relays (AC-SSR). DC type solid-state relays use power semiconductor transistors as switching elements (such as BJT, MOSFET, IGBT) to control the ON/OFF state of DC load power supply; AC type solid-state relays use thyristors (such as Triac, SCR) as switching elements to control the ON/OFF state of AC load power supply.

3. For communication solid-state relays, they can be divided into zero crossing triggering type, peak triggering type, and random triggering type according to the control triggering time.

Zero crossing AC switch: In an AC circuit, the switch is only switched when the voltage waveform passes through zero to reduce the interference and current surge caused by the switch.

Peak voltage AC switch: In AC circuits, switching is only performed when the voltage waveform passes through the peak value, and is generally rarely used.

Random phase AC switch: In an AC circuit, the switch can be switched at any voltage waveform moment, used for applications that require precise control.

4. For AC solid state relays, AC-SSR can be divided into single-phase AC solid state relays and three-phase AC solid state relays.

5. According to the different switch components, it can be divided into ordinary solid-state relays and enhanced solid-state relays.

Ordinary SSR relays use a three terminal bidirectional thyristor switch as the output switching element, while enhanced SSR relays use SCR anti parallel as the switching element.

6. According to different combinations of input and output types, they can be further divided into:

6-1. DC Input AC Output Solid State Relay (DC-AC SSR Relay)

6-2. DC Input DC Output Solid State Relay (DC-DC SSR Relay)

6-3. AC Input AC Output Solid State Relay (AC-AC SSR Relay)

6-4. AC Input DC Output Solid State Relay (AC-DC SSR Relay)

7. According to the composition of the contacts, they can be divided into: 1a, 1b, 2a, 2b, 1c, 2c, etc

A normally open solid-state relay;

A normally closed solid-state relay;

Two normally open solid-state relays;

Two normally closed solid-state relays;

A set of solid-state relays for conversion;

Two sets of solid-state relays for conversion;

……

8. According to the implementation method, it can be divided into spring coupled solid-state relays, transformer coupled solid-state relays, optocoupler solid-state relays, and hybrid solid-state relays.

The one that controls the action of the load terminal through LED diodes and photosensitive devices is generally called an optocoupler relay, which is the optocoupler type relay mentioned above.

9. According to the circuit structure, it can be divided into discrete structure solid-state relays and hybrid structure solid-state relays.

Discrete structure solid-state relays are mostly assembled from discrete components and printed circuit boards, and then encapsulated with epoxy resin, plastic sealing, or resin coating. Hybrid solid-state relays use thick film combination technology to assemble discrete components and semiconductor integrated circuits (ICs), which are then encapsulated in metal or ceramic shells.

10. According to the size of the load, it can be divided into standard solid state relays and industrial solid state relays.

The rated current of standard solid-state relays is generally 10A to 120A, while the rated current of industrial solid-state relays is relatively large, ranging from 60A to 2000A or greater. Therefore, industrial SSR relays can meet the strict requirements of industrial environments and industrial machinery.

11. According to the installation method, it can be divided into board mounted solid-state relays (or surface mounted types), DIN rail mounted solid-state relays, and printed circuit board mounted solid-state relays (or PCB mounted types, which can also be divided into direct insertion type THT and surface mount type SMD).

12. According to the application situation, it can be divided into general solid-state relays, bidirectional transmission solid-state relays, automotive solid-state relays, latch solid-state relays (input signals are used as logical XOR, or XOR operation), so any input can lock/unlock the output, and so on.

These are the most common classification methods for solid-state relays, and the specific types can be selected according to specific application requirements. Solid state relays, due to their absence of mechanical components, have advantages such as high speed, low noise, long lifespan, and high reliability. They are commonly used in fields such as automation control, temperature regulation, and lighting control.