VOL. 8

No. 11

THE picture on HE picture on our cover this month shows part of the buildings owned and occupied by the Eastman Kodak Co. on State Street near Station 3. The 16-story office building which towers so far above its fellows is erected on the site of the original Kodak building, and by its height and beauty symbolizes the wonderful growth of this industry which has made Rochester known all over the world and has given it the name of the "Kodak City."

The total requirements for electric power, steam and gas of this entire group of buildings, considerably less than half of which show in the picture, are supplied by the Rochester Gas & Electric Corporation.

Two electric services are furnished. One of these from our Edison System is heavily reinforced by special cables run directly from Station 3 with a minimum capacity of 1200 kilowatts. The other is an alternating current service furnished at 4150 volts with a present capacity of 1400 K. V. A. This is used in part for a 500 H. P. synchronous motor operating at the service voltage and direct connected to an air compressor. For lighting, heating and small motors, the voltage is stepped down to 230 volts by means of a bank of six 150 K. V. A. transformers located in a vault under the sidewalk. The maximum combined electric demand during 1920 was 1646

kilowatts and the total kilowatt-hours consumed were 3,642,940. As this load develops, it is the intention to put additional load on the alternating current service, keeping the direct current supply where it is now.

The steam supply is furnished by two mains extending from Station 3 through a tunnel which follows Factory Street, crosses State Street, and extends about half way up Kodak Street where the mains enter the basement of the Eastman Building. A low pressure steam service is furnished for heating during the heating season through a 16-inch main, and a high pressure service for industrial purposes is furnished throughout the year through a 5-inch main. The total consumption of low pressure steam during 1920 was 57,989,800 lbs., and the total use of high pressure industrial steam was 24,268,000 lbs.

Gas is also used in many of the manufacturing processes in the Camera Works and is furnished from this Company's regular mains. The amount used during the year 1920 was 8,567,000 cubic feet.

The group of buildings formerly owned by the Woodworth Estate which adjoins this group has been recently purchased by the Eastman Kodak Company so that there is every reason to believe that their requirements for our service will be greater in the future.

HERE have been three stages in

the Edison System. Other sets of

pany's electric distribution system. There was first the series system, now used only for street lighting; next the Edison System, still used to supply most of the service in the central part of the City, and finally the alternating current system which supplies all other electric service and is making large inroads on the territory of the Edison System.

The framework of the Rochester distribution system is similar to that of most of the larger cities. Practically all power is now generated as three phase alternating current at 11,000 volts and is carried at this voltage by underground cables, called tie lines, from the generating stations to the substations for transformation or conversion. There are two exceptions to this general arrangement. At Stations 3 and 5 the substation and generating stations are combined and at Station 4 power is generated as direct current and fed directly to the Edison System. In laying out these tie lines, the first consideration has been reliability of operation. To obtain this, the cables have as far as possible been run over different routes and a sufficient number of lines have been run to each substation to insure continuous service even though one line is out of service through accident or repairs. At the substations, of which Station 35 is typical, the greater part of the power received is passed through transformers to supply the three phase, four wire, 4150, 2400 volt alternating current distribution system and the transformers controlling the series lighting circuits. Another part passes through transformers and rotary converters emerging as direct current to be fed into

change still another part of the 11,000 volt alternating current energy to 600 volt direct current which is supplied to the distribution system of the New York State Railways whose cables are run into the substations.

The alternating current distribution system consists of three phase, 4 wire feeders emanating from the substations and each supplying the load in a certain district of the City. Those feeders which are long and supply a considerable territory are equipped at the substation end with induction regulators which automatically raise and lower the feeder voltage as the load on the feeder increases or decreases. The regulator

control is adjusted so that constant voltage is automatically maintained at the load center of the district supplied by the feeder. As the load center shifts due to new load being connected or rearrangement of lines, the control equipment must be readjusted. Practically all the A. C. feeders run underground from the substations to the districts to be supplied. The general plan for a district is for the feeder to traverse the center line of the territory served, the primary mains branching off from the feeder at right angles on all principal streets. Due to the number of diagonal streets in Rochester it has been necessary in many cases to diverge considerably from the ideal arrangement described. After arriving at the district to be served the feeder and mains may be overhead or underground depending on the character of the streets traversed. Due to the number of shade trees on most of the residence streets of the City and the desire to make these streets present as attractive an appearance as possible, the policy was adopted many years ago of using underground primary distribution to a far larger extent than is usual in cities the size of Rochester. Fuses are installed on primary mains at the junction point with the feeder so that any trouble on the main will not affect the entire feeder. The mains may be single phase two wire or three phase four wire depending on the amount and character of load to be supplied by them. In purely residence districts primary mains are usually single phase but where power service is to be supplied in addition to the lighting load, as at schools, markets and dairies, three phase mains are required. The primary mains supply the transformers which step down from 2400 volts to 120/240 volts, the latter being the voltage on the services to the consumer's premises.

A transformer usually supplies a

Fig. 2.

Showing House Riser and Wiring That Connects Consumer to Rear Lot Construction System

section of secondary main paralleling the primary main and from this secondary main consumers on its street and rear lot lines supplying intersecting streets are fed. One of the most difficult problems connected with the layout of the distribution system is to arrange the transformer spacing and the wire size of the secondary mains in such a way that the lowest annual cost is incurred at the same time supplying satisfactory service to all consumers. The rear lot line system in which this Company is a pioneer was adopted to keep the secondary mains off the streets. This plan consists of setting the poles along rear lot lines, distributing overhead to the rear of the houses. These rear lot line poles are occupied jointly with the two telephone companies, so that, with underground fed street lamps, there are no overhead wires residence streets in the newer sec

on