Phoenix Contact Solid State Relays
Solid state relays have no moving parts like electromechanical relays, but utilize electrical components and optical properties of solid state semi-conductors to perform IO switching functions and isolation. They are designed for applications that require high switching speed without arcing or contact noise. They are highly resistant to vibration and shock and are unaffected by the presence of dust, gases or other contaminants. Solid state relays are used in heating control applications for a compressor’s soft-start, fan, blower, heater and valve control. They are used in lighting applications for dimming and for their ability to operate silently and switch quickly. Because of their resistance to shock and vibration and non-arcing, motion control applications such as lifts, hoists conveyor systems and elevators are the perfect fit for solid state relays.
Phoenix Contact PLC-INTERFACE solid state relays have an overall width of just 14 mm with switching voltages up to 250 VDC and 10 A possible. The hybrid design ensures lower power dissipation and an increased service life, and offers the perfect compliment to the existing hybrid variants for AC voltages. The relays are highly reliable thanks to comprehensive load tests and high quality requirements. They offer safe switching of different DC loads due to optimized matching between the semiconductor and the relay.
Relays: Electromechanical vs Solid State
Electromechanical relays (EMR)
Electromechanical relays (EMR) use physical moving parts to achieve the desired functionality. These moving parts include the contacts that switch between the normally open and normally closed stationary contacts in the relay. This movement is made possible by an electromagnet. When power is applied to this magnet, it will act on the movable contact causing the relay to switch. In an EMR, it is common to hear the switching sound that is represented as a “clicking” noise. This audible noise can be helpful when determining the functionality of the relay.
Solid-state relays (SSR)
Solid-state relays (SSR) use a low power, electrical signal to generate an optical semiconductor signal that will transmit and energize an output signal. When this is activated, the input optical signal will act as the switch, allowing a higher voltage signal to pass through the relays output components. The internal circuitry of a SSR is far more complex than an EMR, but there are no physical moving parts.