Page top


Omron uses cookies to improve your experience on this website. By continuing to use the website, you hereby agree to our Privacy and Cookie Policy

Lead Contents

General-purpose Relay: Clear Relay Case Turned Black

FAQ No. FAQ02811

Primary Contents


The clear relay case has turned black. Is there a problem?


Carbon and contact dust generated by the organic gas that results from arc discharge during load switching accumulates on the inside of the case. The discoloration is not a problem.

If using an inductive load, a surge suppressor can be introduced as a countermeasure against discoloration caused by arc discharge.