Control switches

Electrical devices of this group differ in variety both in terms of purpose and design. In the electrical equipment of metal-cutting machines, mechanisms, machines and automatic lines, switches can perform both direct inclusion of control circuits (for example, when selecting certain modes), and serve for operative inclusion in regulation modes of various drives (low drive servomotors, electromagnets, hydraulic and pneumatic springs, electromagnetic couplings).

Depending on the purpose, a distinction must be made between single and multi-chain control switches, as well as switches for 2, 3 or more positions. Thus, with the help of control switches, the simultaneous closing and opening of electric circuits can be carried out, and depending on the connection scheme of its movable contacts, different combinations of switching on and off of all connected electric circuits are provided.

Multi-circuit control switches differ in number of sections, contact closure scheme and handle rotation. An example of the most popular single-circuit device is a universal switch of the UP5300 series.

Universal switch of the UP5300 series: a — general view, b — design of the working section

Depending on the design, control switches can be made with knobs or rotary knobs. In the second case, the combinatorial ability of the switches turns out to be higher: they can switch a large number of electrical circuits (be multi-circuit), allow different combinations of closed and open contacts for each position of the handle, and can also have contacts of different designs: in addition to classic NO and NC contacts, lagging contacts, sliding contacts, etc. can also be made. This facilitates solving a number of problems encountered in the design of relay-contact control circuits.

PE switch

Control switches should also include such devices as cross switches, which are quite widespread in mechanical engineering. This is explained by the fact that, in addition to high combinability, such devices facilitate, thanks to mnemonics, the maintenance of a machine or an automatic line.

Cross switch PK12

In metal-cutting machines, electrical devices of this type are usually used to control magnetic starters of reversible asynchronous motors (for example, see diagram of radial drilling machine 2M55, when with the help of a cross switch, the spindle motor and the motor responsible for the movement of the cross head are controlled), as switches for operating modes (for regulation, semi-automatic or automatic modes), disconnecting devices or for connecting separate devices devices or control circuits in regulation modes...

Universal switch for PKU3 series

Usually, the switches are installed on the control panels: yes, individually for each machine and centrally - control a group of machines or a line to perform operations related to issuing centralized commands or control elements of transport devices. Therefore, the control switches work under relatively good conditions and are not subject to any special requirements regarding their mechanical strength and protection against harmful environmental influences.

In addition, since such devices are turned on relatively rarely (compared to other switching devices used in automatic control systems), there are no special requirements for them in terms of their high breaking capacity and the permissible number of switching. At the same time, the control switches must provide reliable closing and opening of the contacts so that the electrical circuits do not open over time. In addition, the front of the control switches should be well designed so that it does not detract from the look and feel of the control panels.