PSR-MC38 Safety Relays Phoenix Contact PSR-MC38 Safety Relays are safety relays for emergency stop, safety doors, and light grids up to SILCL 3, Cat. 4, and PLe. These safety relays feature 1- or 2-channel operation and automatic or manual, monitored start, 2 enabling current paths, and 1 signal output. Phoenix Contact PSR-MC38 relays provide a TBUS interface for connecting CONTACTRON Pro hybrid motor starters and MINI POWER power supplies.