Each pole of the relay is phase segregated and operates independently via its level detector and interface area. The provision of the interface area allows for the factory fitting of output relays to the customer's requirements. With this flexibility the interface area relays can be manufactured with up to 9 change-over contacts, connected as phase segregated groups of three, or as three phase outputs. The standard arrangement is with 4 normally open output contacts.
Each level detector initiates a time delay, set by the user, which delays operation of the output relay. This can be set to zero for instantaneous operation.