The Relay is a mechanical switch. A tiny arm moves inside the relay providing either an open or closed contact. A FET switch (Field Effect Transistor) is a solid state switch, no moving parts. The FET switch is designed for interfacing to a PLC.
The maximum rating for the FET is 36 VDC @ 100mA. The Relay is designed for interfacing directly to a device such as a light buzzer or another relay. The maximum rating for the Relay is 60 VDC/VAC @ 1A.
Here’s a table highlighting the main differences between a relay and a FET (Field-Effect Transistor):
||FET (Field-Effect Transistor)
|Electromechanical device that uses an electromagnetic coil to control the switching of contacts.
||Electronic device that uses voltage applied to a gate terminal to control the flow of current between source and drain terminals.
|Contains moving mechanical parts, including an armature and contacts.
||Solid-state device with no moving parts.
|Can handle both AC (Alternating Current) and DC (Direct Current) signals.
||Primarily used for DC applications but can also handle AC signals with certain specifications.
|Typically slower switching speed due to mechanical movement.
||Generally faster switching speed since it operates electronically.
|Has a limited lifespan due to mechanical wear and tear.
||Has a longer lifespan since it has no mechanical parts to wear out.
|Suitable for higher current and voltage applications.
||Suitable for lower current and voltage applications.
|Provides electrical isolation between control and switched circuits.
||Does not provide electrical isolation and may require additional circuitry for isolation purposes.
|Generally larger in size and bulkier.
||Smaller in size and more compact.
|More susceptible to electromagnetic interference (EMI).
||Less susceptible to electromagnetic interference (EMI).
|Higher power consumption due to coil energization.
||Lower power consumption as it operates based on voltage control.
|Audible clicking sound when switching.
||Silent operation since there are no moving parts.
It’s important to note that this table provides a general comparison between relays and FETs. Different types of relays and FETs may have specific characteristics and applications that deviate from the general characteristics mentioned here.