A switching order lists every operation in sequence, such as open this breaker, rack out that one, open these disconnectors, apply earths here, with the location, device number and person for each step. It is prepared and checked in advance, issued by the control room and carried out by field operators who repeat back each instruction. It ends in a safety document such as a permit to work, and restoration follows the steps in reverse.
Step 14 of the switching order says close the line earth switch, confirm the line disconnector is open and locked first.
Also heard as
- switching programme
- switching program
- switching sheet
- switching schedule
Related terms
Permit to work
Formal written authority to work on equipment that has been isolated, earthed and declared safe.
Tag out
To hang a danger tag on an isolation point so nobody operates it while people work downstream.
Rack out
To wind a withdrawable breaker out of its connected position in metal-clad switchgear to isolate it.
SCADA
Supervisory control and data acquisition: the system that lets a control room watch and switch remote plant.