When relay activates, the NC terminal disconnects through the COM terminal and stays open until the relay is deactivated. Why do relays click? Every time a relay clicks it is an indication from the contacts opening/closing in the event the coil is run. Some relays create a louder clicking sounds https://cruzhrag17518.iamthewiki.com/7995816/optimierung_der_e_mail_kommunikation_der_einsatz_eines_newsletter_mailservers