Complete switchgear units of mine standard version
Complete switchgear units of mine standard version КРУ-РН-УХЛ5-ВВ type are designed for distribution of the electric power of 6/10 kV voltage and 50 Hz frequency in the networks with isolated neutral terminal in different industrial sectors, as well as in underground mines and pits not dangerous on the explosion of gas, steam or dust.
Construction of КРУ-PH
Construction of КРУ-PH consists of:
- Busbar compartment;
- hardware compartment;
- input compartment;
- micro-controller protections compartment.
Construction of КРУ-PH
Basis of the construction of КРУ-РН is the principle of mounting all the basic elements of electric circuit – a switching unit, current sensors (Rogowski loop) and an auxiliary potential transformer (НОЛ) at the single base (high voltage hardware block - БАВ).
High voltage hardware block БАВ is moved along the horizontal guides, general busbar of the distribution device is located in the rear bottom part of КРУ-РН. Input compartment is located above the busbar – there are binders for the power cable connection in it. There is also space for allocation of ОПН and current transformers (current transformers are needed to be installed for electricity accounting only, function of the control over phase current is carried out by Rogowski loops).
While designing КРУ-РН, specialists of EXC took into account specific requirements caused by the operation conditions in pits and mines not dangerous on gas and dust. Thus, critical parameter is the height of the equipment – sometimes the roof of the pit is rather low. So, the busbar is placed in the rear bottom part of the cabinet. Such an approach provides for both sides service and allows minimizing the height and the width of КРУ-РН, enlarging its depth. As the cable is connected to the mine cabinets from above (from cable bridges, located on the roof of the working), busbar placement in the bottom part is reasonable and provides minimum overall dimensions of the unit.
Component arrangement of КРУ-РН allows the allocation of the relay compartment with micro-controller units МКЗП and БКИ, low-voltage equipment and other equipment in the front upper part of the cabinet, the most convenient place for visual control. Case of КРУ-РН has the protection degree from the external impacts IP54.
Advantages of КРУ-PH
КРУ-РН has its own auxiliary potential transformers (НОЛ), which provide the power supply of operating circuits of the cabinet. Thus, there is no need in the cabinet with auxiliary potential transformers for the power supply of РП.
Moreover, transformer НОЛ has the winding that allows keeping the measuring of the network voltage with accuracy enough for the realization of relay protections, that's why there is no need in additional cabinets with voltage transformers within РП. In case the technical or commercial accounting is needed the following can be done:
- Install voltage transformers in the КРУ-РН cabinets, chosen in accordance with the rated current load;
- install the КРУ-РН-TH cabinet on each section of busbars to control the voltage of all three phases;
- choose and install electricity supply meters.
Current control in a wide range
Control over the phase currents is carried out by Rogowski loops. Micro-controller units МЗКП work with the signals from these sensors. Advantage of Rogowski loops is the linear characteristic in a wide range – from 30 to 1000 A. That is why the КРУ-РН cabinets can be used within this range without any additional adjustment.
Plug-in contacts of the roll-out element work as a disconnector in all КРУ-РН. That is why the cabinets of intersectional breaker КРУ-РН-C have the disconnector and don't need the installation of the intersectional disconnector cabinet КРУ-РН-CP. However, when two-sectional РП is installed in two rows, it is necessary to provide the installation of КРУ-РН-CP to remove voltage from the power busbar bridge between the rows.