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the modification/updating to be performed on the system study detailed as:
existing electrical power plant. • short-circuit current calculation;
Cear has carried out a document defining the electrical • load flow calculation;
Power System Operating Criteria for the area located in • motor starting analysis.
the existing plant section and in the new plant section.
The scope of this document was to describe the power
system operating criterion and the different scenarios The improvement of the Power
in which the electrical system may operate. In particular, Plant
the document described the overall power system
configuration, with the representation of the operation Consequently, according to the electrical studies, Cear
criteria of generation, existing 6.6 kV Medium Voltage has developed a new “Overall Single Line Diagram”
switchgear, existing Low Voltage switchgear and new that was representing an update of the present power
Low Voltage switchgear. plant extended with an additional electrical station for
Aim of the new electrical study was also to re-define the new plant.
and translate in a workstation’s software the control As per updated Overall Single Line Diagram, Electrical
and monitoring of the extended electrical power plant. system configuration included some modification on
In addition to that, the customer required to have the the electrical equipments installed in the existing
whole power study calculation, to check the protective electrical substations; existing 6.6 kV Medium Voltage
relays setting value in order to assure protection to the switchgear needed to be updated and modified to
users and obtain selectivity in case of faults into the connect the relevant outgoing circuit breakers as
electrical network. follow:
Basically, the protective philosophy was based upon • Two existing outgoing CB (Circuit Breaker)
the knowledge that the faults or abnormal operating connected to the existing two 1.6 MVa step down
conditions can be lead to: (6.9 / 0.38 kV) transformers for feeding the 0.38
• overloads; kV LV (Low Voltage) switchgear of the existing
• ground faults; substation;
• phase to phase and three phase faults. • Two existing outgoing CB connected to the new
Fig. 3 – The Medium two 2.5 MVa step down (6.9 / 0.4 kV) transformers
Voltage Switchgear The study was conducted with the following power for feeding the 0.38 kV LV switchgear of the new
plant;
• Two new outgoing CB (obtained adapting the
existing independent 6.6 kV cb) connected to the
new two 2 MVa step down (6.9 / 0.38 kV)
transformers for feeding the existing 0.4 kV LV
power center in case of loss of power generation
in its substation;
• One new outgoing CB (added) connected to a
new flashed gas compressor main motor.

The improvement of the plant required also some new
electrical equipment as:
• Two new gas generators each of rating 2.5 MW to
feed existing 6.6 kV switchgear in existing
substation;
• One new diesel generator 1.6 Mva connected to
the new 0.38 kV LV switchgear to be used either
as emergency or as stand-by generator.

In addition to that, was foreseeing also a new Electrical
Power Module Building based on a modular metallic
structure covered by insulated panels designed and
supplied by Cear including all technological facilities
required by the environmental condition as:
• HVAC (Heating, Ventilation, and Air
Conditioning) system;
• Pressurization system;

IndustrIal Plants - May 2018
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