CONTROL AND RELAY CABINETS TYPE KRO
 
By integrating the secondary scheme subsystems, the advantages of static design and modular construction have resulted in standard solutions of protective and control functions, i.e. into factory wired and tested units for protection, automation, control, signalling, measurement, DC and AC auxiliary supply in associated feeders, electrical interlockings and cable marshalling -in a single standard product -the Control and Relay Cabinet KRO which represents the entire segment of the electric control room of the plant.
 
KRO
 

These self-contained units include thus all subsystems of secondary schemes (including all preparations for remote control). The entirety of the plant control room is obtained by simply composing these "sandwiches". Both physical and electrical integration has been achieved for: control board, indication panel, measurements, relay panels, DC and AC auxiliary supply and cable marshalling for remote control.
This novel approach to the design and construction of secondary equipment subsystems saves on an important part of the work - the electrical design (operating diagrams have become the component part of KRO cabinets -only cable connection diagrams have to be made). The required space in the electrical control room and the time of installation, testing and putting into operation on the site have been minimized.
Any future transfer to an unattended substation within the remote controlled system will require minimum equipment and work.

Control Relay Cabinets

The cabinet door in mosaic technique bears the mimic diagram with control elements, indicators and annunciation display elements. Each unit is an electrically and physically self-contained whole. The continuity of mimic diagrams is accomplished by the simple arrangement of cabinets in rows.
The front, supporting plate in the cabinet interior bears the surface mounted elements of DC and AC auxiliary supply of associated feeders. The supporting frame (swing-out or fixed type, depending on the method of external wiring) bears, in a vertical arrangement, modular protective subsystem racks and annunciation of the associated feeders (following the single-pole diagram on cabinet door) including the functions of electrical interlocking and preparation for remote control.
 

Relay Cabinets RO

In cases where modular protective systems are employed as a design replacement for conventional relay panels, relay cabinets type RO are available.

Protective Relays in Individual Cases MZK

Modular construction of the system permits to taylor "per feeder" segments as required. If a distributed arrangement of the secondary schemes in medium voltage cubicles, i.e. a distributed arrangement of individual functions is required, it is possible to install separate cases as a partition in the cabinets. All the advantages of the modular system come to full expression: electromechanical self-dependence of the protected feeder, flush or surface mounted case with conventional screw type terminals and lead sealing protective cover as required. The degree of protection is IP42 as standard (to IEC 144), up to IP54 upon request.

Such standard solutions are available to our standards (including the associated operating and wiring diagrams). If you face or will be facing an engineering problem we are ready to solve it with you and create optimum solutions for an existing or future construction phase. All we need is a well-defined single-pole diagram of your substation. The best technical and cost-effective solution will then be selected in close collaboration with you.

Modular Protective System Power Supply

Cabinets are powered from a station battery of 220 V DC, 110 V DC, 48 V DC or upon request via a DC to DC inverter which supplies output power of ± 24 V DC for electronics and provides galvanic isolation from battery circuits. The applied inverter unit has a regulated, overvoltage protected output, reverse polarity protected input and short circuit protected input and output thus eliminating a great deal of failures often encountered in the DC auxiliary supply circuits.

Mechanical Construction

Cabinets are supplied with swing-out frame (wiring accessible from cabinet front by swinging out the hinged frame) or as a free standing structure (accessible from cabinet front or rear side).
Depending on the specific requirements, it is possible to obtain a clear and compact (and low space requiring) arrangement with all the advantages of a factory wired and functionally tested modular protective system.
 
Wiring methods
 
The connection between modules and the 19" plug-in rack is made via standard connectors with the plug connector arranged on the module and the socket connector on the mating position in the rack. The connection from that point to the "designer's block, is made either directly or via a plug and socket connector.
The plug and socket connector (crimping wiring technology is used on the socket side) which receives all connections toward the external world, makes the entrire 19" rack mechanically and electrically exchangeable. After the plug and socket connector is disconnected and the high current capacity connector withdrawn, the entire rack ("feeder") is electrically and mechanically isolated from the plant, i.e.from the cabinet terminal block; this canbe done while the plant is energized without disturbing the operation of other serial devices/relays on the same core of current measuring transformers.
 
 
An important feature of the system hardware is the connection method of current modules on the rack and on the cabinet terminal block. The connection toward the external world -the secondaries of current measuring transformers is made via a special 8-pole high current capacity connector. Upon withdrawal of current modules, the current connector short-circuits the secondaries of the current measuring transformers (a detailed description of this can be found in the catalogues).

  
 
Module combination
 
The individual modules comprising the i functional subsystems are plugged into racks (wired manually or by a computer controlled machine). They are secured by lead sealing locking rails bearing module identification tags (the employed symbols are from the operating diagrams).
 
This modular approach permits the composing of individual relays and their combinations into subsystems and systems of protection and automation; the same approach appears with the installation of modules into individual housings and/or complete relay cabinets.