A few sharp raps on the vertical operating pipe or suddenly applied tugs on the operating handle may help to free an iced switch mechanism. Power-operated switches should be operated periodically to ensure that the switches and their mechanism and control features are functioning properly. Where the circuit conditions will not permit operating the switch energized and the circuit cannot be deenergized for this purpose, it is suggested that arrangements be made to disengage the operating mechanism from the linkage to allow the control circuits and mechanism to be checked, provided that this method does not adversely affect the over-all adjustment. It is common practice to use these devices to interrupt small values of current such as the charging current of a short length of transmission or distribution line, transformer magnetizing current, or light load current. It should be recognized that such operation results in unconfined electric arcs at the switch contacts which under unfavorable conditions may cause damage to the switch, and which may involve adjacent phase conductors or supporting structure in the initiation of system faults.
Transfer switching in parallel or loop circuits also has the same attendant hazards.
If current interruption is contemplated, care should be taken to be sure that the current magnitude is in a range that can be handled by the switch with a good probability of successful interruption. American Institute of Electrical Engineers Transactions, vol. Transformer Magnetizing Current and Its Effect on Relaying and Air Break Switch Operation. AIEE Transactions, vol.