Disconnect Switches

Disconnects allow the operator to isolate various pieces of equipment in the substation. When opened, they are essentially like removing a section of bus.  There are contacts on both end of the disconnect.  Most contacts on high voltage disconnects are made of a highly conductive material such as silver.  These contacts will remain closed for years between normal maintenance and during that time will be subject to every kind of weather know to man.  High resistance in the connection will exhibit heating, thus easily detected by infrared inspection.  However several scenarios can cause heating of a good contact, which the thermographer must be aware.   Many times simply operating the switch will remove the problem by realigning itself and or cleaning surface corrosion. If operated while the infrared thermographer is present, he/she can verify the problem has been temporarily fixed.  This does not eliminate the need of having to schedule maintenance for that switch.