A Revolutionary Concept for 33/11 KV Power Sub-Stations:

11 KV Hut type Sub-Stations, a unique product developed by Meditron, installed in conjunction with 33 KV Circuit Breakers (Outdoor Kiosk type), provides an ideal alternative to conventional 33/11 KV Power Sub-Stations involving lot of civil construction. The Unitised Sub-station is a totally enclosed weather-proof, Vermin-proof, dust protected and depending upon site conditions to have extra protective coverings / insulations to make it suitable to work under the local weather conditions. It is housing the total electrics with necessary protective arrangements as required for an 11 KV substation. In general it comprises of the following:

• 11 KB VCB with all necessary protections for the Incomer along with protections for the 33/11 KV Transformer.
• It is connected internally with Bus arrangements and houses 4 Nos. of outgoing feeders of 11 KV and 2 nos incoming feeders of 11 kV.
• It is having necessary battery charger with the DB and standby battery to supply the 30V / 48V Control supply for the protection of the system.
• It houses a Computer along with UPS with necessary software for down-loading and processing of the data collected by the data loggers.
• Suitable Data Loggers are provided for recording the tripping of the Incomer feeders and outgoing feeders under various conditions of overload, fault, manual tripping and tripping due to the 33 KV side. It also has facility for recording of the various parameters of power, current, power factor, up to 15th harmonics and also record the date and time of event every hour.
• Hut is made out of sheet steel having proper ventilation and two nos of doors. The walls are insulated with fiberglass and internally lined with decorative aluminum sheets.
• It is having proper incoming and out-going termination facilities with suitable terminal boxes with arrangements for power cable terminations.
• The termination boxes are weatherproof and even under heavy rainy conditions there shall not be any ingress of water.
• It is having facility to connect 415 volts supply for and protection control utilities of the Sub-station from a external transformer.
• Suitable lightening arresters provided for the substation.
• Three type of Earthing provided – LT/Electronic, HT Earthing and Earthing of the lightening arresters.

The distinct advantages of the proposed solution are:

• Highly economical with land required as low as 220 sq meter. 15X16 or 10X22 meter plot
• Minimum construction time (2-3 months).
• Minimum land requirement (as low as 500M2-600M2 for a 2X5 MVA S/S, with 10 Nos. outgoing 11 KV feeders).
• Very low volume of civil work and steel structures.
• High reliability with minimum maintenance ( factory built and tested under expert hands)
• Free from breakdowns caused by atmospheric disturbances, such as high wind, heavy downpour and lightening etc.
• Aesthically designed to suit the site topography gives a pleasing appearance

Highlights of Proposed Arrangement

• Termination of incoming 33 KV overhead line on a 4 pole structure. 33 KV LA's, PT and Isolator to be mounted on the same structure.
• Connection between the 33 KV Isolator and 33 KV circuit breaker (Kiosk mounted) shall be through 33 KV XLPE armored cable.
• Connection between 33 KV circuit between and primary of 33/11 KV transformer is also through 33 KV XLPE cable.
• Secondary side of 33 KV/11KV transformer shall be connected to the 11 KV incomer circuit breaker installed inside the factory built hut type Sub-Station with 11 KV XLPE armoured cables..
• The outgoing 11KV Overhead line feeders shall be terminated on 2 pole structures installed at suitable desired locations along the periphery of the Sub-station. These 2-pole structures shall also be used to mount 11 KV LA'S and 11 KV Isolators with DO fuses. These 11 KV Overhead line feeders shall be connected to the 11 KV Outgoing circuit breakers (installed inside the hut type Sub-station) through 11 KV cables XLPE cables.