Operating experience with Petersen coils on 66-kv system of Metropolitan Edison company

THE Metropolitan Edison Company, operating in the eastern part of Pennsylvania, has a total of 264 miles of 66,000-volt overhead transmission lines, to which interconnections at this voltage with the systems of the Pennsylvania Water and Power Company and the Pennsylvania Power and Light Company add 59 miles, making a total of 323 circuit miles. A single-line diagram of this system is shown in figure 1, which also shows the various types of line construction used, ranging from all-wood construction to all-steel construction, with overhead ground wires and counterpoise. The system neutral is grounded through transformers at West Reading, Middletown, and the Holtwood station of the Pennsylvania Water and Power Company. At West Reading, the grounding bank consists of three single-phase 500-kva 66,000–13,200-volt transformers connected wye-delta, and at Middletown a three-phase zigzag transformer having an equivalent transformer capacity of 1,000 kva. At Holtwood each 66,000-volt line, as shown in figure 1, terminates in a 20,000-kva three-phase 69,000–13,200-volt wye-delta transformer, having the high-voltage neutral grounded through a 300-ohm reactor. The 13,200-volt winding of these transformers is connected to the 13,200-volt station bus.