Flat step switch

The flat step switch (also known as a slide switch ) is a device for regulating the voltage of electric motors . This type of switching mechanism was mainly used in locomotives with an electrical main drive to regulate the speed.

function

The basic structure of a flat-way tap changer consists of a slide and a movable contact slide attached to it. The slide can either be driven by an electric motor or by hand by means of cable and chain hoists, which can involve considerable effort for the operator. Pairs of contacts are attached to the slideway, the contacts of each pair being electrically isolated from one another. Half of the contacts are connected to the transformer taps , the other half to the vehicle drive. When a switching step is engaged, the slide moves to one of the contact pairs and creates an electrically conductive connection between the contacts.

Some switches are designed in such a way that when switching to the next level, contacts of different levels are briefly connected by the slide. This has the advantage that during the switching process there is no tear-off spark that could corrode the contact surfaces and that acceleration can be carried out almost without jerks. On the other hand, an interturn fault occurs on the transformer side, which has to be dampened by resistors . In other designs, the main current is interrupted by a load switch in order to enable voltage-free switching over.

Rail vehicles in which the flat track step switch was used are, for example, the DR series E 16 and the SBB Ae 3/6 I and Ae 4/7 locomotives .

literature

• Franz Eberhard, Hansueli Gonzenbach: Fascination Ae 4/7. A witness to the great Swiss locomotive architecture (= LOKi. Spezial. 22). Goldach trade press, Zurich 2003, ISBN 3-85738-073-X .