Augmentation and Upgradation of 66 11 KV Grid Substation at PGIMER, Chandigarh.

Design, Supply, Installation / Erection, Testing & Commissioning of 66/11kV, Star/Star, Outdoor type, 16MVA Power Transformer suitable for 3-Phase, 50Hz AC supply. The transformer shall be copper wound transformer (Electrolytic grade 99.9% pure copper, Core made of first grade Cold Rolled Grain Oriented (CRGO) Core grade MOH or better having oil & air cooled system. The Vector group shall be YNyn0. Winding Insulation level (kV/peak) on HV side 140 and LV side 28. The losses of transformer at ONAF rating (at full load at 75 deg. C) shall be No load losses 15KW(Max), load losses 85KW(Max) and Auxiliary Losses 2KW(Max). Rated short time withstand current (kArms) for 5 Seconds 31.5 . The impedance of transformer shall be max 10% on 16MVA base without negative tolerance. On Load tap changing arrangements on HV side. The OLTC gear shall be designed to complete successfully tap changes for the maximum current to which transformer can be loaded i.e., 150% of the rated current.

The tap changer shall be provided for variation of HV voltage with a tap setting of (+) 5% and (-) 15% at 66kV side of each 1.25% steps which shall be operated from either OLTC or Remote control equipment. OLTC shall have AVR and master slave relay for parallel operation.The remote control equipment shall be enclosed in an indoor sheet cubicle to be located in control room. Complete with all accessories and safety provisions as per relevant IS Code including first filling of filtered dehydrated oil, i/c supplying and grouting of suitable M.S. Channel with all accessories and transformer shall be confirming to IS : 2026 (Part 1 to Part 5), IS : 1180 and duly ISI Marked and as per CPWD specifications complete in all respects etc as required at site. The maximum flux density in any part of the core and yoke at rated voltage and frequency shall be such that the flux density with + 12.5 percent combined voltage and frequency variation from rated voltage and frequency does not exceed 1.9 Tesla. Inside of tank shall be painted with varnish or liquid resistant paint.

For external surfaces one coat of thermo setting powder paint or one coat of epoxy primer followed by two coats of polyurethane base paint shall be used. IS: 1180 (Part 3) shall be referred to for paint thickness for normal to medium corrosive atmosphere. For highly polluted atmosphere and special application external paint work shall be as per direction of Engineer-in-Charge. Design ambient condition : a) air temperature 50 deg C, b) Relative Humidity 90 % Max, c) Seismic Zone IV. Noise level Shall not exceed limits as per NEMA TR-1 with all accessories running measured as per IEC 551 / NEMA standard. The transformer should have QR code which should contain drawing, test report OEM manual,Geo- Tag of manufacturing location etc. Marking Each transformer shall be provided with rating plate made of anodized aluminum/ stainless steel material securely fixed on the outer body, easily accessible,as per IS: 1180 Part-3. The entries on the rating plate shall be indelibly marked. The transformer shall be suitable for continuous rating for full load.

The temperature rise shall not exceed 45°C in oil and 50°C by resistance in winding. Transformer shall operate under naturally cooled (ONAN) condition up to 12.5 MVA, beyond this it shall be operated though forced cooling (ONAF). The cooler units shall be 2x50% capacity and each 50% cooler shall have one standby fan & one extra radiator. The cooler control cabinet shall have two sections. One section shall have the control equipment exclusively meant for cooler control. The other section shall house the temperature indicators, auxiliary CT’s and the terminal boards meant for termination of various alarm and trip contacts as well as various CT secondaries. The Transformer shall be provided with suitable devices to monitor temperature & pressure. Automatic operation control (Switching in and out) of fans/ pumps shall be provided (with temperature change) from contacts of winding temperature indicator. The supplier shall recommend the setting of WTI for automatic changeover of cooler control from ONAN to ONAF.

The setting shall be such that hunting i.e., frequent start stop operations for small temperature differential do not occur. Suitable manual control facility for cooler fans and oil pumps with manual / automatic selector switches and push buttons shall be provided. The transformer shall be suitable for controlling & monitoring from OLTC / RTCC / SCADA.

The following fittings shall be provided:- Two earthing terminals with the earthing symbol ,Oil level gauge indicating oil level at minimum, 30°C and maximum operating temperature, Rating and terminal marking plates, Silica gel breather, Drain-cum-sampling valve (¾″ nominal size thread, IS 554) preferably steel with plug for three phase transformers, Thermometer pocket with cap, Oil filling holes having (1¼″ nominal size thread), Lifting lugs for the complete transformer as well as for core and winding assembly, Pressure relief device or explosion vent , One filter valve on the upper side of the tank , Unidirectional flat rollers, Inspection hole HV side neutral grounding strip (where one of the HV bushing terminal is connected to earth),Buchholz relay, Bird guard, Oil temperature indicator and winding temperature indicators with suitable tripping mechanism above permissible limit, Jacking pads, Additional Neutral separately brought out on bushing for earthing, Magnetic oil level gauge with low oil level alarm contact, Non return valve (for conducting pressure test), Monogram Plate,

Inspection cover, Detachable type radiators with top and bottom shutoff valve, Oil Conservator with Oil level indicator, minimum level marking and drain plug, Necessary hardware, clamps, lugs etc. for termination on HV/MV etc. for all transformers. Unloading from trailer on to the plinth. Complete as per technical requirements and as directed by EIC. NOTE: Transformer cost shall inlcude filtration and testing of oil at the time of installation and testing and commissioning of transformer.