Switches must be pass many different tests during the approval phase. Some of these tests involve the switching behavior under different load conditions, the switch is tested on nominal load, overload and at many cos?. Additionally the switch will be checked on switch on and switch off procedures. The paramters must be everytime the same during this tests.
In the past, air chokes were used as inductive loads, since these do not saturate. Air chokes are larger and have a stronger leakage field than comparable core chokes with corresponding magnetic energy.