MID/AN/31

Repairs to 2.5MVA Automatic Voltage Regulator-I, by way of isolating various units of AVR from power supply main and controlling supply while following all safety measures pre/during work. It includes visual and close inspection of main transformers (step up/down transformer and Buck-Boost Transformer) for excessive corrosion and oil leakages, if any in chamber, conservator tank, radiator, etc. Checking of bushing for oil leakages, chips and cracks developed if any in the insulator. Checking of winding temperature indicator, Oil temperature Indicator thermometer, pressure relief valves, Buchholz relay. Checking quality and quantity of oil in the chambers, checking Di-electric strength/ BDV of transformer oil, insulation resistance value of transformer windings, earthing connection and its conductivity. Repairs to Voltage Regulator unit by way of draining out oil from the chamber in suitable container, opening top cover and extracting out coils and Roller assembly with the help of suitable mechanical/manual tools & tackles and cleaning of coils by removing carbon chips/deposition using cotton cloth and suitable solvent. Replacing worn out cạrbon rollers-48 nos. tag and tail-48nos.and refitting coils along with roller assembly in the chamber with the help of appropriate mechanical/manual tools & tackles. Cleaning inside of oil chamber to remove all kind of unwanted deposition and sediments. Checking the existing oil for its specified di-electric strength/BDV and refilling in the chamber. Topping up with fresh transformer oil 660 ltrs. In units of AVR. Opening motor control box for inspecting/servicing of Servo motor with control system by replacing defective/damaged components such as Aux. contactor 03 for minimum run down (CLS)- 01no., Limit Switches- 02nos., Time delay relay – 01no. All of reputed make having actual specification as that of damaged ones . Replacing silica gel of breather assembly. Dismantling of incoming and outgoing connections of voltage regulator unit from their respective terminal boxes. Removing the overheated/damaged portion of connection cable ends along with thimbles of single 3 core 240 mm sq armoured Aluminium cables. Providing and fitting of 04nos. of leads approx. 1.25 Mtrs long each, made out of 50mmsq. Multi -strand copper cable bent to shape to connect coils with outgoing terminal points with the help of copper thimbles provided at either ends of the leads Complete job includes cost of material, labour charges, to & fro transportation, loading, unloading charges for all tools & tackles required for execution of job and all applicable taxes.. Testing of AVR after repairs for all connected parameters with periodic observations.

M/S RAGHUNATH MECHANICAL AND ELECTRICAL ENGINEERING WORKS

NATIONAL ELECTRO-MECH COMPANY