Silver Impregnated Graphite (SIG) Contacts

Many types of contacts in electrical control gears, circuit breaks and relays are used either to make or break electrical circuit or transfer contact from one element to another. These contacts are essential parts of sensitive parts of the sensitive relays and their satisfactory operation depends on the material of contacts in use. The common contact materials like copper, silver, and metals of high melting points suffer from several drawbacks e.g. excessive wear, welding, over heating, formation of high resistance films and material transfer. Silver impregnated Graphite Contacts combine the best properties of high conducting silver refractory for graphite material base contacts are widely used in Railway signaling relays. The technology for manufacture of SIG Contacts was developed at NPL, New Delhi and the Corporation has licensed the process to a large number of companies who are catering the services to meet the requirements of the Railways.