The Gas Insulated Switchgear (GIS)

·         The Gas Insulated Switchgear (GIS) shall be a complete unit comprised of main equipment, all control, monitoring, protection, measuring and auxiliary devices and systems including interconnections, all termination

·         Joints at interfaces, mechanical linkages, couplings, SF6 gas piping, cabling, wiring, grounding materials etc. required for proper and satisfactory operation.
·         The GIS shall be of compact and modular design with individual equipment modules connected together to form a complete assembly. However, combined disconnect switch and grounding switch, cable termination, PT, exit bus duct and CT (with cores located within gas compartment) shall be in separate gas tight compartment. If, CT is installed in breaker gas compartment; insulation class for CT shall be class F. of either single-phase enclosure type or three-phase enclosure type for voltage levels of 230kV and below. of single-phase enclosure type for voltage level of 380kV. Installed on suitable pads or supporting frames/structures with provision for leveling, including fasteners to foundation, which shall also be included in the supply. Support-structures shall be designed and fabricated to withstand the short circuit forces of the ground fault current.
·         GIS shall having expansion joints and flexible connections, where several enclosures are connected in the longitudinal direction, such as main bus. Expansion joints provided for installation alignment shall be locked in place when alignment is complete. Expansion joints for compensation of thermal expansion and erection tolerances shall have
·         the means to preserve mechanical integrity of the enclosure and the plug-in contacts for the conductor. Provided with galleries, stairways, movable platform or walkways for accessing the equipment above two meters for maintenance and operation.
·          All structures, movable platform, galleries, stairways and walkways shall have grounding provision and shall conform to the relevant Occupational Safety and Health Administration (OSHA) regulations.
·         For single-phase type GIS, creation of single gas zone by external piping connection between the phases is not acceptable. Also, external piping connection (with normally open valve) to create common gas zone (between same phase) in single-phase type GIS is not acceptable.
·         The GIS enclosure shall be safe to touch and fully ensure operational security and personnel safety under all normal and fault conditions with the maximum allowed induced voltage in the enclosure of 65 volts.
·         The switchgear and all its components and accessories shall be designed for minimum maintenance during service. The manufacturer shall state the minimum interval between minor inspections (which will be restricted to visual checking and adjustments of external parts only) and major inspection/overhaul, including refilling or replenishment of gas and cleaning of the contaminant or filter in the circuit breaker chamber(s).
·         Suitable openings shall be provided in the circuit breaker, disconnect and grounding switch modules for major inspection/adjustments.
·         All motors shall be in accordance with IEC 60034. The bearings and other such parts shall be permanently lubricated for the entire service life. Padlocks shall be made of stainless steel or brass.
The GIS interface points shall be carefully coordinated with other equipment such as overhead lines, cables, transformers, reactors, capacitor banks, etc., supplied by other manufacturers in order to ensure full compatibility. The design criteria for outdoor

SINGLE BUS BAR ARRANGEMENT

This is the simplest switching scheme in which each circuit is provided with one circuit breaker. This arrangement offers little security against bus bar faults and no switching flexibility resulting into quite extensive outages of bus bar and frequent maintenance of bus bar isolator(s). The entire SubStation is lost in case of a fault on the bus bar or on any bus bar isolator and also in case of maintenance of the bus bar. Another disadvantage of this switching scheme is that in case of maintenance of circuit breaker, the associated feeder has also to be shutdown

Exothermic welding installation guide

Here is a guide for exothermic  welding system

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Shock indicator for new materials

Protect-A-Pak is a single use shock indicator that can be attached to the item being shipped or inside of shipping boxes via a self-adhesive backing. Protect-A-Pak is composed of a cylindrical plastic casing containing two springs, each of which is fitted between two steel balls. These springs are designed to withstand a specific rated g-force. If the acceleration exceeds the rated force, the two balls detach from the axis affected and fall into the plastic casing. As the springs are fitted at a 90 degree angle, each Protect-A-Pak can monitor two axes. A label on the outside of the packaging shows the shipper that an impact indicator is being used.

High voltage Transmission line bending due to a sand storm in Egypt

 A sand storm caused a totally bending  in a high voltage  transmission line in  Egypt .

Cable reels specifications (part 2)

• When lifting cable reels by crane, a steel shaft of proper length and diameter shall be placed through the reel drum spindle. The steel shaft shall be threaded at both ends and provided with circular plates and retaining nuts to prevent the reel from falling in case of accidental tilt during the lifting process
• When rolling a cable reel from one location to another, care shall be taken to remove any objects on the surface area that might contact the cable surface. The marked rolling direction must be followed to prevent the cable layers from becoming loose
• The cable storage site shall be an elevated flat surface and must not be reached by flood or sea water
• Reels shall be stored on a solid support or hard and regular surface that will not allow the flanges to sink into the earth.
• Storage areas shall be free of construction equipment, flying or falling objects, chemical or petroleum spill or sprays, open fires or other heat sources and far from heavy vibration areas.
• The conductor or ground wire in reel shall be protected by wood lagging to prevent damage. The conductor reels are set or stored on ground blocking. It is advisable to store the different types of conductors in separate locations. Blocking shall be used to prevent movement or rolling of reels. When the conductor or ground wire is not protected by wood lagging, in no case, shall the blocking touch the conductors or ground wire.

Source SEC standard

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