Page top

Lead Contents

FAQ02083 of Solid-state Relays FAQ

FAQ No. FAQ02083

Primary Contents


What is the zero cross function?


The zero cross function causes the Relay to turn ON when the AC load power supply approaches 0 V to suppress noise generated when the load current rises suddenly.

There are two types of noise: noise on power lines and noise emitted into open spaces. The zero cross function is effective against both types of noise.

A very large inrush current flows when lamps and similar equipment are turned ON, but the zero cross function causes the load current to always flow from a point near zero so that inrush current can be suppressed more compared to Solid-state Relays that do not have the zero cross function.

Ideally, the function turns ON near 0 V, but restrictions in the circuit configuration cause it to operate within the range of 0 V ±20 V. This voltage is called zero cross voltage.

Recommended Products


Best-selling, general-purpose relays that can be selected based on operating environment and application


Power-switching Compact General-purpose Relays

G3PE (Three-phase)

Compact, Slim-profile SSRs with Heat Sinks. Solid State Contactors for Three-phase Heaters Reduced Installation Work with DIN Track Mounting.

Other Solid-state Relays FAQ