Difference between optical relay and electrical relay

Optical relays are essentially solid-state relays, and their differences from electrical relays (i.e. ordinary relays) are mainly reflected in the following aspects:
working principle:
Light relay: It is a device that integrates light emitting and light receiving devices. The input end uses infrared light emitting diodes (IR LEDs) to control the opening and closing of the receiving end MOSFET (metal oxide semiconductor field-effect transistor), and the control is achieved through optical signal transmission. The input and output sides are electrically insulated, but the signal can be transmitted through optical signal transmission.
Electric relay: mainly relying on the principle of electromagnetic induction, by applying voltage at both ends of the coil, the coil generates a magnetic field, attracts or releases the armature, thereby achieving the closure or disconnection of the contacts and completing the on/off control of the circuit.
Isolation performance:
Optical relay: Isolation is achieved between input and output through optical signal transmission, without direct current or voltage connection. This isolation performance helps prevent interference in the input signal from being transmitted to the output terminal, enhancing the safety and stability of the circuit.
Electric relay: Although it can achieve circuit isolation to a certain extent, the isolation effect is relatively weak compared to optical relay, and there is a certain possibility of electromagnetic interference.
Response speed:
Optical relay: It has a fast response speed because the transmission speed of optical signals is faster than electrical signals, enabling high-speed switching.
Electric relay: The response speed is relatively slow because it is affected by the inductance of the coil and the action of mechanical components, and the attraction and release of the armature require a certain amount of time.
Mechanical structure:
Optical relay: without mechanical moving parts, it does not produce mechanical wear, therefore it has the advantage of long lifespan, and there is no noise or vibration during operation
Electric relay: There are mechanical contacts that generate certain noise and vibration during the process of attraction and release, and the wear of mechanical contacts can affect the service life of the relay.
Electrical characteristics:
Optical relay: It has the advantages of low operating current, high isolation voltage, and low leakage current.
Electric relay: usually requires a large driving current to excite the coil, in order to generate sufficient magnetic force to drive the contact action.
Application scenarios:
Optical relay: commonly used in applications that require electrical isolation, fast response, low noise, long lifespan, and strict requirements for signal interference, such as measurement equipment, communication equipment, security equipment, medical equipment, semiconductor testing equipment, etc.
Electric relay: commonly used in general circuit switch applications, such as industrial control, household appliances, automotive electronics, etc., suitable for situations where response speed is not high and load power is large