The control cabinet provides state analysis and control of the operation of electrical heating systems.
The systems used for control can be manual or automatic. It is recommended to use the automatic assemblies working on the basis of indicators of temperature regulators. Control cabinets for electrical heating have a metal case and are subdivided into:
Outdoor (IP65), UHL1;
Indoor (IP31), UHL4.
control by means of temperature measuring instrument regulator;
control by means of the free and programmable device (controller).
Entrance part, depending on category of power supply of a case, can be described as follows:
1. The first category of cabinets has two mutually redundant power cables, between which switching is carried out in the automatic mode.
In case of one system of collecting bars, two introduction triple-pole automatic switches operated by the device of automatic transfer circuit-breaker(ATCB) are used.
In case of two systems - the third triple-pole automatic switch used as section is added to the scheme of automatic transfer circuit-breaker.
2. The second category also has two mutually redundant power cables, but switching between them is carried out in the manual way.
In case of one system of collecting bars two introduction triple-pole automatic switches with realization of mechanical blocking of their simultaneous switching on are used.In case of two systems - two input and one section triple-pole automatic switches with realization of electric blocking of simultaneous switching on of all three automatic switches are used.
3. The third category has one power cable, which is connected to the input triple-pole automatic switch.
4. Zero (N) and protective (PE) conductors of power cables are connected to input N and PE plugs (bars).
The power part can consist of the following devices:
1. In case of choosing as RCBO protection:
One - or the triple-pole automatic switch of differential current (RCBO);
Additional contact for RCBO ( Participates in formation of signals "Accident" and "Heating is on");
2. In case of choosing as AS+GFI protection:
One - or the triple-pole automatic switch (AS);
Switch of differential current (GFI);
Intermediate relay (for formation "Accident" signal);
3. Contactor (from one to three depending on need for control on phases);
4. Additional contact for contactor (participates in formation of "Heating is on" signal);
5. Terminal clips (for connection of power cable);
6. Cable termination(for cables with section from 16 mm2 inclusive);
7. A set for cable armor grounding (for armored cables with section less than 16 mm2).
The control part includes:
1. The unipolar automatic switches protecting circuits of control (secondary circuits);
2. The switch, modular contactor or intermediate relay (for switching on the control scheme on a cabinet door);
3. Measuring regulator of temperature or controller;
4. Temperature sensors;
5. Light signaling hardware on a cabinet door;
6.Terminal blocks, intermediate relays participating in signaling on a cabinet door and in dispatching office.
On the basis of measurements of the controlling sensors, the device receives data on whether heating of the roof is required. Regulators allow to adjust a working interval of temperatures, usually the range is set from +3 or 0 and to-8 or-10 C.The manual mode assumes switching on of system by a person. The automatic control cabinet can be equipped with such option too, it is useful at malfunctions with a temperature regulator. The door has a display panel for control of operability of the device.
Total cost differs, depending on parameters (rated current, type of sensors, mode of work and others). Small and low-power cabinets can be bought in Moscow for 10-13 thousand rubles, and large and multipurpose models with a high working power, large number of groups for connection and a possibility of installation outdoors can cost 35-40 thousand rubles. The guarantee of the plant, the brand of the producer, estimated quality of products and the period of trouble-free operation are also important factors influencing the price.
Choosing a ready control cabinet or assembling accessories for it independently, it is necessary to be guided by the specific project. Special importance is represented by:
Each system has specific features, which surely should be considered. Also all are guided by different levels of execution, quality and operability of the cabinet.
Control cabinet provides the analysis of state and control of work of heat tracing systems.
Control cabinet may have the operator control panel.