Inductive Load Unit Toroidal Inductors NPT LD TD-AF

Electrical switches must pass many different tests during the approval phase. Some of these tests concern the switching behavior under various load conditions. The switch is tested at nominal load, overload, and several cosϕ values. In addition to continuous load, switching on and off processes are also examined. During this process, it is crucial not to change the set parameters throughout the entire test. In the past, air-core inductors were used as inductive loads because they hardly saturate. However, air-core inductors are larger and have a stronger stray field than comparable iron-core inductors with corresponding magnetic energy. To set the respective cosϕ value, additional adapted resistors must be connected. To meet all required test points, many different inductive and ohmic loads must be available. This special toroidal design of the air-core inductor retains the advantage of a linear inductance curve over current and still has a very small, negligible stray field comparable to a saturable iron-core inductor.