Contactor and relay terminal markings should conform to DIN EN 50005 standard.
The markings make it possible to determine the terminals that are associated with the ship component, ie functions they are assigned to and standardize the markings for different manufacturers on ship electrical system.
Terminal markings adjacent to main contacts have a single digit reference.Three-phase contactor main contact pairs are designated with: 1-2; 3-4; 5-6.
Terminal markings adjacent to auxiliary contacts have a double digit reference numbers so that:
• The first digit is the contact’s position (the position digit) which indicates where the contact is physically situated on the block, ie 1,2,3,…, 8
• the second digit defines a contact’s function and is called the function digit.
Function digits have been given the following DIN standardized designations
Standardized designations for contactors
Break contacts (NC) have function digit 1 and 2
Late break contacts (LB) have function digits 5 and 6 also known as ‘Normally close Late’ (NCL)
Make contacts (NO) have function digits 3 and 4
Early make contacts (EM) have function digits 7 and 8 also known as’Normally open Early’ (NOE)
Change over contacts (CO) have function digits 1-2-4
Each auxiliary contact that is utilised by relays and contactors is clearly designated, the reference numbers are stamped on both sides of the contact terminals.
