Primary network installations at boston

THE BOSTON EDISON COMPANY has three primary network installations in operation on its system supplying a total load of 43,000 kva. The first primary network installation went into service in 1932 to supply a residential load of approximately 4,500 kva in an area of about 5.3 square miles. This load was supplied with four 1,500-kva transformers rated 13,800-volt primary and 4,330-volt secondary installed in underground vaults 30 feet long by 9 1/2 feet wide by 10 feet high. The transformers, as originally installed, were connected Y-Y with a tertiary-delta winding but they were later rewound for delta-Y operation in order to put the network in phase with the existing radial system which is supplied from delta-Y connected transformers.