DIAGRAM INFORMATION
SYMBOLS - RELAYS
The relay symbols below are used on AT and ATW diagrams.

Looking at the single winding relay - "A" is the relays circuit code, "2000" is the coil resistance and "2" is the number of contacts.  "a" and "e" are the coil tags.

When special contact materials are used the symbol representing the contact unit is also marked to show the type of contact materials.  The material codes are:- Palladium - Pd, Platinum - Pt, Mercury - Hg, Tungsten - W and special alloys - Sp.  Platinum contacts also have a notch cut in the end of each contact tongue, whilst Palladium has a semi-circular notch.

 
 
BACK Home page BT/GPO Telephones Search the Site Glossary of Telecom Terminology Quick Find All Telephone Systems

Last revised: November 12, 2021

FM