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Normal Clad Duplex Switchgear

The electrical switchgear represents the fundamental unit in the energy distribution chain, and must meet the needs set and defined by utilities, producers of green energy, end users of electricity.

C.R. Technology Systems S.p.A. has designed a special version of its Normal Clad, called Duplex.

This solution is technically ideal in applications where spaces are limited, such as on off-shore platforms and/or naval applications.


Every column is composed by two overlapping units which are completely independent from each other in the power circuit.

Each of the two units consists of the following power compartments which are metallically segregated: power cable compartment, MV circuit-breaker compartment, upper and lower main busbar system.


Every unit in the column is equipped with two circuit-breakers, each one having his own feeder connection cable outlet, common to the same point of MV cable connection.

This solution is very useful both in systems that require redundancy and continuity of service, and in those in which carrying out unscheduled maintenance could create a serious process/production problem, or even worse (as in the case of naval applications) it could cause the loss of entire branches of the plant or motors.

In order to allow the insertion and extraction of MV circuit-breakers without sacrificing the maximum degree of safety and simplicity of operation, C.R. Technology Systems with this solution includes the supply of a circuit-breaker extraction trolley with adjustable height and hydraulic pump movement.

The extraction trolley allows bringing both the circuit-breaker on the lower floor and the circuit-breaker on the upper floor to the technical ground level.

Busbar system

The overall rated current of the busbar system is given by the sum of the currents of the two half-busbars: upper and lower. Both the upper and lower busbar systems are available in bare copper bars, sheathed bars, resin-coated bars, in addition to silver or tin plating treatments in the case of specific projects with applications in aggressive environments that require it for a lasting continuity of service and with less wear as possible due to environmental conditions.

Low-voltage compartment

The central part of the column hosts the low-votlage compartment, equipped with low-voltage components for the protection and control of the MV circuit-breakers, among which:

  • Protection relays
  • Measurement and control devices
  • Low-voltage protection circuit-breakers
  • Components of command and control

Power compartment, MV cable connection area

This compartment is equipped with the following components:

  • Current transformers
  • Homopolar residual current transformer
  • Earthing switch positioned on MV cable connection


Each column is equipped with a duct for the evacuation of the gases produced by the potential generation of an electric arc, positioned on the top of the column itself.

The two units (lower and upper) in the case of internal arc, will evacuate the potential overpressure generated by two separate gas evacuation ducts, so that a fault in the lower level does not compromise the upper level, or vice versa.

Normal Clad Duplex Switchgear
Normal Clad Duplex


C.R. Technology Systems carries out Normal Clad Duplex cubicles according to the following electrical characteristics:

Rated Voltage 12 kV 24 kV
Rated Voltage insulation 28 kV (1min) 50 kV (1min)
Impulse Test Voltage (BIL)
75 kV 125 kV
Main busbar rated current
Fino a 4000 A Fino a 3600 A
Main bars rated current
1250 A
2000 A
2500 A
3150 A
3600 A
4000 A
1250 A
2000 A
2500 A
3150 A
Short time rated current
Fino a 50 kA (3s)   Fino a 40 kA (3s)  
Rated frequency
50-60 Hz 50-60 Hz
IP Protection degree
Loss of service continuity (LSC)
Arc-proof version IAC AFLR
25 kA (1sec) 25 kA (1sec)


C.R. Technology Systems has carried out a project for Cayo Coco and Cayo Guillermo, located in Cuba, to enhance the distribution and production of electricity supply necessary in these two developing tourist areas, including the construction of hotel structures.

The project engineering team of C.R. Technology Systems carried out a study aimed at solving the problem of limited space at the MV plants and substations located in the province of Ciego de Ávila.

The project in question included the study, construction and supply of nr. 5 Normal Clad Duplex 13.8kV 1250A 25kA (1s) switchboards, as well as a remote command and control panel (system mimic) and SCADA supervision system.

Finally, downstream of the development and construction of medium voltage (MV) switchgear object of the supply, C.R. Technology Systems installed and commissioned the panels.

Below is the link to the page where further details about the project are reported.