• Nadirsha Shahabudeen

Equipments in the Electrical Substations

Updated: Feb 10

The main items of equipment contained in the electrical substations supplied for various projects were:

• Transformers

• Electrical Panels

• HVAC System

• Fire &Gas System

The substations were completed with the following systems:


• Lighting system and sockets

• Lightning protection system

• Internal and external telecommunications system

A. Transformers

Resin transformers from 0.5 MVA to 2 MVA, 10/0.4 kV were installed in ventilated rooms allocated exclusively for this purpose or in cabinets placed next to the panels to which they are connected with busbars.

Transformers are the heaviest equipment (about 5,000kg) and cannot be installed subdivided into modules. For transport the lower part of each transformer was anchored to rails with bolts, the top part was secured with straps to the structure of the module. Special attention was given to the anchoring of each transformer during transport and dimensioned to withstand the oscillations and accelerations of the barge and lorries that transported the modules. The transformers were installed in a way that allows them to be removed if replacement should become necessary. In the transformer room F&G sensors for smoke detection and infra-red sensors to check for temperature shall be installed. For fire and gas detection, electronic smoke sensors shall be used or a pipe system installed at the transformer ceiling. The monitoring of the temperature shall be made with infra-red sensors close to the bolted connection from the transformers to the bus-bars.

B. Electrical Panels

Panels insulated with SF6 gas for voltages of 110 kV, 35 kV and 10 kV and air insulated panels for voltages of 400 V were installed in the substations.

GIS room with 5 GIS “diameters” and control panels

Each panel is controlled locally by a synoptic panel installed at a distance of few metres so that the local operator is not affected by thermal effects generated by an electric arc inside the panel. The panels supplied are certified to contain the internal arc in accordance with the relative Standard.

Every panel contains overload and short circuit protection devices and communicates with the central supervision system through copper cables and fibre optic cables.

A temperature control system of the connections between busbars with infra-red sensors is also installed in each panel. Another feature of the panels is the internal arc detector systems using special fibre optics installed along the busbar routes of the panel, in the area where external cables are connected and where the transformers are installed.

C. HVAC System

Every substation is heated, cooled and ventilated by a climate control system which draws in external air, treats it and introduces it into the substation through metal ducts. There was also an overpressure system, chemical filtration, which interfaces with the Fire & Gas system to ensure safety.

Double HVAC indoor type unit for modular substation

D. Fire & Gas System (F&G)

A Fire & gas detection system was designed in order to provide fast detection of a fire or gas inside the building and/or presence of hazardous gases around the building boundaries, to properly identify its location – giving to safety operators all the information related to act - and to take automatically pre-programmed action to reduce risks.

The F&G system was able to communicate with other systems in order to carry out the safety procedures. The FGS was designed so as to avoid a single point failure which may hinder the integrity, reliability and capability of the overall system at all times during operation.

Fire & gas detection system mainly consisted of the following equipment:

• Fire and Gas Alarm Control Panel

• Smoke detectors

• Heat detectors

• Gas detectors (CH4, H2, H2S and O2)

• High sensitivity smoke detector (HSSD) (below raised floor)

• Manual push buttons

• Sounder

• Beacon

• Monitoring and command modules, connected on the wiring loops

A detection system for fire and hazardous gases such as H2, H2S and CH4 was installed in every modular substation. The system consists of sensors installed in the ceiling and the false floor, connected by local concentrators to the central control panel. In the case of smoke or fire or an increase in temperature or the presence of hazardous gases, the F&G system produces acoustic and visual alarms inside and outside the substation, immediately

closes the dampers in the air ducts and sends a signal to the HVAC system which initiates the operations necessary to isolate the substation from the external environment.

The F&G system also communicates with the central supervision system through copper cables and fibre optic cables. The F&G detections system consists in smoke detections sensors installed in the room ceiling / false floor and with heat sensors infer-red type places close to the electrical bolted connections. In case of large and high rooms where there is no

interferences with structures, beams, cable trays, high equipment, the system with laser beams scanning the room ceiling shall be adopted.

The content of this article is taken from web open source. The blogs are intended only to give technical knowledge to young engineers. Any engineering calculators, technical equations and write ups are only for reference and educational purpose.

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