Design and Manufacture of Neutral Ground Resistor for 33/11 kV, 31.5 MW Substation تصميم وتصنيع مقاومة ارضية محايدة للمحطة الثانوية 33/11 كيلوفولت ، 31.5 ميكا واط

Abstract

The neutral ground resistor (NGR) is used for limiting fault current in alternating current network . Calculation , design and manufacturing of (NGR) are carried out for substation (33 / 11 kV , 31.5 MVA) , according to (IEEE-32 : 1972) standard . Three models have investigated , to drive an electrical model for calculation and design then study a manufactured sample of resistor plate from stainless steel material (AISI 316) . When comparing the measured value of resistance with calculated value the deviation was less than (5 %) . A complete mechanical design for (NGR) is done and heat analysis is carried out by assuming a (300 A) current pass through resistor for (30 sec) show heat distribution in (NGR) plates , where hot spot was in the middle plates and maximum temperature was (502 oC) which was lower than IEEE required (610 oC).