[Trade Journal]
Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
vol. 40, no. 11, p. 556-566, col. 1-2
PACIFIC COAST ENGINEERING PROBLEMS
(The discussion at the recent Del Monte conventions brought problems out much that is valuable in solving electrical problems of the West in the present crisis. The report of the first day’s session was begun in the last issue of the Journal of Electricity and is continued here, together with discussion as brought out in the remaining sessions of the Engineering Section.—The Editor.)
Edward Whaley in a discussion of F. H. Fowler's paper on this subject, contributed the following:
There is undoubtedly existing today a critical condition in the power markets of Central and Northern California, aggravated by subnormal conditions of rain and snowfall, a rapidly increasing demand for power and the necessity for curtailing the use of fuel oil in order that this form of fuel may be available in adequate quantities for maritime needs and other war activities for which no other source of power can be substituted. It must be admitted without argument that fuel oil must be conserved to the greatest extent possible and that agricultural and war production demands for power must be met and that in California, at least, this can be done by the substitution of power generated by falling waters.
In Mr. Fowler's able exposition of the subject he has shown, and in fact it is and has been a matter of common knowledge, that the possibilities of hydroelectric development in this state are ample to meet all demands that may be expected for many years to come; but we are now faced with a situation of national importance in which two factors arc of primary importance, viz : the delivery into the market of a large block of power and the delivery of this power in the shortest time possible. Any discussion of the problem which does not realize these two factors as absolutely controlling in the present emergency is purely academic.
As between two or more developments of sufficient magnitude, that development should be made which can be placed in operation within the shortest time.
The next point for consideration is the number of man power days necessary for completion and the season when same will be required. This is of particular interest both as to the total amount of labor to be drawn from an already insufficient supply and also as to the ability to prosecute all or a considerable part of the work under favorable conditions throughout the winter months, when the call for labor for planting and harvesting is non-existent.
The final point for consideration is the amount of money which must necessarily be diverted from other purposes to furnish the necessary amount of power to fully meet the present emergency. From all present indications the war promises to be of such a duration that the financial resources of the country will be strained to the utmost before a victorious 'conclusion is reached and it is only sane procedure to accomplish all necessary results with the minimum of expenditure now, when the burden seems comparatively light.
In the report of the committee representing electric utilities appointed by the Railroad Commission to investigate power conditions and possibilities for Northern California, and also in the report prepared for the commission by its own engineers, it appears that a development of 100,000 horsepower at the present time in a plant capable of producing this amount continuously throughout the year as a base load will meet present requirements.
Mr. Fowler, in his paper, pointed out that there were at least three possible developments in Northern California that would produce this amount of power, namely, the combined project of the Great Western North Fork of the Feather River and Yellow Creek project of the Pacific Gas & Electric Co., the Pacific Gas & Electric Pit River project and the Northern California Power Company's Pit River project.
The development of the Pacific Gas & Electric Pit River project cannot meet the present emergency as the estimated time to complete is five years. The Feather River project has been estimated to take two and one-half years and the Pit River project of the N. C. P. Co., Cons., to take 18 months. In point of time, therefore, the latter project is in a class by itself. The entire flow line is only five and one-fourth miles long, of which approximately 10,000 feet is tunnel, divided into five sections, the longest of which is only 3450 feet in length. From this it at once becomes apparent why this project can be developed so much sooner than the Feather River project, where fourteen miles of tunnel will have to be driven.
The pipe lines are only 800 feet long, so that the demands on the steel plate mills, already overloaded and behind on deliveries to our shipbuilding plants, will be a minimum and much less than for any other development projected.
The amount of tunnels will permit the prosecution of a large proportion of the work when labor will be most available and the open ditch section is of such dimensions and the formation of such character that power driven machinery will be used largely to the exclusion of manual labor.
In point of total cost, this project will call for by far the least money, and will cost far less per unit of output than any other possible development and this low unit cost will be a low immediate cost and not one to be attained some time in the far distant future after many millions of dollars have been spent on other power plants to be finally operated as part of the one comprehensive scheme.
Mr. Fowler stated as his personal view that he favored the project of the Pacific Gas & Electric Company as against that of the Northern California Power Company, Consolidated. I infer that this preference arises out of the fact that the Northern project excludes some portions of the fall of the Pit River which are included in the Pacific Gas & Electric project, and that he is fearful that for this reason the utmost ultimate development will not be made of the latent possibilities of this stream. This is the viewpoint of the extreme conservationist, but in this case there can be no room for controversy on this point as the topography of the country makes it perfectly feasible to include these sections of the river in other developments which will undoubtedly be made in later years.
The water resources report of 1912 shows the potential possibilities of this stream as from 450,000 to 600,000 horsepower, depending on whether flood waters are stored at its head or not. Except for that part of the stream embraced in the Northern project, those parts of the stream which the Northern excludes but the Pacific Gas includes compare favorably with the remainder of the stream as regards fall per mile so that their ultimate utilization is only a matter of time.
The original filings on this stream, together with the original surveys of both the Northern and the Pacific Gas projects, were made by the Northern California Power Company. These preliminary investigations were started in 1902 and after spending a number of years and a good many thousands of dollars, it was decided that the advantages of the present Northern project were so great as compared with any other that this ought to be the first development on the Pit River.
This decision was made after the most careful investigation had shown that this particular project could be constructed in less time and for less money than any project in the state of California, having an equal all year output. The present emergency only emphasizes these advantages and adds one more, which is now perhaps all important, and that is that, for an equal amount of power, far less man power will be requisitioned for this than for any other project.
SHORTAGE OF FUEL OIL
J. M. Buswell contributed the following: If it is true that the fuel oil supply will become exhausted in the near future to such an extent that it will be necessary to control the distribution of, not only the fuel oil, but electric energy generated by fuel oil, to what may be considered as non-essentials, it would seem advisable that the committee arrange to make an immediate survey or investigation, producing statistics that will establish the possible saving of fuel in two ways: First, by improving the load factor by changing loads from one time of day to another; that is, by improving the diversity factor of the various principal loads. Second, by reducing the peaks, by curtailing the distribution of energy to non-essentials, at least over the peak period, when it is customary to carry at least part of those peaks on steam units.
It might be suggested that these investigations be made before the crisis has been reached, so that, when the time comes, the companies will have data ready to show the field of possible fuel saving and the result of curtailment of profitable load, which will reduce the earnings, probably to such an extent as to require an adjustment of rates, in order to assure the operating companies a proper return.
WATER POWER CONSERVATION
The several papers on power conservation including the "Questionnaire" (p. 388), "Power Plant Losses," by R. J. C. Wood (p. 344) ; "Improvements in Water Wheel Efficiency," by E. C. Hutchinson (p. 404), and "Hydro-electric Economies," by J. P. Jolly-man (p. 384), were discussed together. The discussion was opened with a written comparison of governing methods by H. A. Barre, as follows:
At the Big Creek installation there is no loss of water or power due to governing. The water conduit from Huntington Lake to Power House No. 1 is entirely a pressure system, so that the whole lake is the forebay. A pond is formed below Power House No. 1 and is connected with Power House No. 2 by a similar pressure conduit and, therefore, acts as a forebay for Plant No. 2. This pond has a draw down capacity of 53 acre feet, or enough to supply Power House No. 2 for nearly four hours.
Both power houses can, therefore, follow the fluctuations of the load without any noticeable time lag.
The control of the water nozzles is by means of a needle valve in a fixed position, which opens and closes in direct response to the governor. If the closing is at such a rapid rate that the pressure in the pipe line increases above a predetermined limit, the bypass opens and discharges enough water to prevent a further increase.
As the pressure falls the bypass closes slowly until the water is entirely shut off.
The contents of the pressure system are such that the drop in pressure on full load opening at the maximum rate, causes such a small drop of pressure that it has no objectionable effect.
The ordinary operations of closing do not produce a sufficient rise of pressure to cause the bypass to operate.
When a very rapid closing takes place, the bypass, or pressure regulator, opens and discharges for a short time, as before described.
Each pressure regulator seldom operates more than seven to ten times per month.
In fact, it may be safely stated that more water has been wasted by routine testing of the regulators than by their operation.
C. O. Poole stated that the experience of the Southern Sierras Power Company has demonstrated the superiority of the bypass needle valve over deflecting nozzles.
John A. Koontz of the Great Western Power Co., in discussing water conservation with turbines, cited a 3 to 4. per cent saving accomplished by the use of replaceable wearing bands shrunk over the outside of turbine runners. The runners are renewed or built up by oxy-acetylene welding, thereby not only saving water but also adding to the life of the runner.
F. D. Nims of the Washington Coast Utilities Co. abstracted a paper contributed by J. B. Fisken of the Washington Water Power Company, giving the results of an investigation of water velocities and separation of losses in a 3260 horsepower turbine installed by I. P. Morris Co. at Post Falls, Idaho. Pilot tubes were employed in the test and every precaution taken to get the most accurate measurements. At a load of 3310 horsepower an assumed water wheel efficiency of .845 and an effective head of 53.01 feet, the total loss of head was 8.34 feet, distributed as follows:
Mr. Nims advised holding low vacuum at the end of the draft tube.
C. O. Poole concurred in the idea, but stated that to prevent hammer this was sometimes deliberately ignored.
Mr. Milford of the Northern California Power Co. stated that a 1-inch standard lip faucet installed in the draft tube had stopped all trouble from water hammer and caused no changes in vacuum head.
E. C. Hutchinson of the Pelton Water Wheel Company stated that water hammer vibrations. occurred when a turbine is underloaded. If the draft tube is kept full they will not occur.
P. O. Crawford of the California-Oregon Power Company described the .equipment of the new Copco plant.
J. M. Buswell of the San Joaquin Light & Power Corporation told of water saving that has been effected in several of their plants by the substitution of auxiliary relief nozzles for deflecting nozzles and by utilizing a small drop below the Crane Valley reservoir to operate a 600 kw. unit.
H. H. Schoolfield of the Pacific Power & Light Company described changes in the Natches canal whereby 50 ft. lost head was utilized to operate a 1900 horsepower turbine driving an induction generator floating on the system and operating automatically.
Paul M. Lincoln of the Westinghouse Electric & Mfg. Co., H. H. Schoolfield, J. M. Buswell, E. C. Hutchinson and J. P. Jollyman participated in discussion on the possibility of providing absolutely automatic operation of induction generators and the advantages and disadvantages thereof.
TRANSMISSION AND DISTRIBUTION LOSSES
R. E. Cunningham’s paper (p. 349) was abstracted by the author.
S. J. Lisberger of the Pacific Gas & Electric Company remarked concerning the lowness of the losses shown, and mentioned the difficulty of making a real comparison of different systems because of different bases of comparison. Distribution losses are especially difficult to analyze. He believes that a reasonable number of transformer burn-outs is good operating practice, and in the replacement of old meters by new types.
H. A. Barre emphasized the high cost of high-grade service. More transformers are installed than arc actually needed, expensive precautions are taken to insure continuity' of service, whereas true efficiency would supply current in the shortest, quickest and easiest way.
L. S. Ready of the California Railroad Commission cited cases where the public had been educated to expect too high a grade of service and unnecessarily large investments made to insure 98-99 per cent continuous service.
L. M. Klauber of the San Diego Consolidated Gas & Electric Company described the working of a system whereby the engineering department is kept informed of changes in load conditions so that transformers may be immediately disconnected. He also brought out the point that dairies, incubators and other forms of agricultural power utilization required a very high grade of service.
R. S. Masson of the Arizona Power Company suggested varying rates for differing service, a low rate for 95 per cent service and a higher rate for 99 per cent service.
L. S. Ready spoke of the difficulty of giving two classes of service from the same line, and suggested that a discount might be given for poor service. Complaints are largely due to lack of education.
P. M. Downing brought out several practical objections to Mr. Masson's suggestion. J. M. Buswell explained how necessary shutdowns have been minimized by a loop system of distribution.
R. J. Lisberger showed the reasonableness of an irrigation consumer's complaint when a noon pump shut-down prevented the operation of his electric range. He recommended a 4000-11,000 volt combination in distribution line practice as being the most economical.
STEAM POWER PLANT ECONOMIES
R. J. C. Wood of the Southern California Edison Company, in contributed discussion, advocated conservation of steam used for atomization by cutting down the number of burners in service when running a boiler on partial loads. The real atomizing efficiency of a burner should be stated in terms of pounds of steam required per pound of oil burned. and not as a percentage of the total evaporation. The results obtained with burners in the Long Beach plant shows practically an inverse ratio as follows:
This represents from 3 to 1 per cent of the total steam used.
The advisability of extra heat insulation for boilers is purely an economic question dependent upon the price of oil and the number of hours per annum of boiler service as compared with the cost of insulation. Likewise with soot-blowers. which remove misplaced heat insulation.
Draft gages, CO, recorders and temperature indicators are well worth while in the boiler room if in charge of a competent man responsible for their upkeep. Otherwise, only disappointment will result.
A rough and ready rule for determining the proportion of electric and steam driven auxiliaries to be used is to use steam up to the point where the feed water will not absorb any more. A glance at the exhaust pipe will indicate if any exhaust steam is being wasted; and if so, some steam driven auxiliaries should be shut down and the corresponding electric driven units started in their place. Mr. Wood has had the same experience as the San Diego Consolidated Gas & Electric Company in choking the steam passages with an excess of condenser tubes and getting an increase of vacuum after removal of some tubes.
W. G. Vincent, Pacific Gas & Electric Company, noted a variation of from 1 to 4 per cent of steam required for atomization by different companies reporting, and suggested investigation by a sub-committee, Chas. S. Delany, Pacific Gas & Electric Company, pointed out that 90 per cent of engine room efficiency is due to design and 10 per cent to operation, whereas in the boiler room operation is the all important thing. The boiler room should be well equipped with instruments that will give the operator full information about conditions and also check up his work. Such scientific methods will increase plant efficiency at least 10 per cent over haphazard operation.
Any endeavor to maintain continuity of service detrimentally affects the efficiency of the plant. Today efficiency is paramount to continuity of service. S. J. Lisberger contended that the term kilowatt hours per barrel of oil is misleading as applied to Pacific Coast plants with low load factors. A curve plotted to show the barrels of oil burned as compared with the number of kilowatt hours generated gives approximately a straight line which is a good index of standby requirements of a plant and also an incentive to plant operators in trying to improve efficiency.
W. G. Vincent deduced the equation of this line as bbl. of oil = C+ a X, when C is a constant depending upon the boiler equipment of the plant, A is a constant dependent upon the kind of oil and X the number of kilowatt hours generated.
John A. Koontz explained that the high efficiency shown by the Great Western Power Company plant was due to the method of operation either under full load or solely as standby, the hydro-electric plants taking care of variation in load.
R. S. Masson described the refinements introduced in the new plant of the Arizona Power Company near Jerome, where oil costs $2.50 per barrel. An efficiency was obtained of 1 lb. of oil per kw. hr. under test conditions (334 kw. hr. per barrel) and 256 kw. hr. per barrel under actual operating conditions with 29 per cent load factor. The initial cost was $105 per kilowatt of installed capacity.
Edwin A. Rogers has found that the elimination of the human element in the boiler room greatly improves efficiency. He described an installation of the Merit oil firing system and of Cope regulators in the Palace Hotel, San Francisco, where from 79 to 80 per cent average operating efficiency is obtained and two firemen eliminated. This 4 per cent saving in fuel and $200 in labor gave a total saving of $500 per month.
Geo. E. Guinan of the Puget Sound Traction, Light & Power Company contributed answers to the questionnaire received from various members of the Northwest Electric Light and Power Association.
POWER PLANT ECONOMIES IN THE NORTHWEST HYDRO-ELECTRIC ECONOMY
1. What percentage of the theoretical energy in the water taken by any of your power houses is realized at the bus-bar?
Washington Water Power Company—Post Falls, 81.4%; Little Falls, 84.1%; Long Lake, 83.5%—on guarantees.
Oregon Power Company-165%.
Portland Railway, Light & Power Company—We have no means In use whereby this is determined.
2. Where this is known, how do you measure your water? Washington Water Power Company—Water wheel tests were made at Little Falls. Practically same method was followed for the tests at Post Falls. Oregon Power Company—By flow meter and cross section.
Portland Railway, Light & Power Company—See answer to Question 1.
3. To what extent does it pay to get an accurate measurement of the amounts of water going through your plant?
Washington Water Power Company—It paid well to accurately measure the water going through the wheels while under test, as the efficiency was a material factor in determining the price to be paid the manufacturers. Except for this reason it does not pay in any degree to measure the water going through the plants accurately. A general knowledge of the amount of water which is drawn from yearly storage through the Post Falls plant is all that is necessary and this is arrived at from the load carried by the plant.
Portland Railway, Light & Power Company—See answer to Question 1.
4. Have you on impulse wheels any automatic system of closing needles to reduce deflection of nozzles, or of closing bypasses opened by falling loads, and to what extent do they improve your water economy?
Portland Railway, Light & Power Company—Do not have any impulse wheels installed.
5. Have you any cases of special value involving the use of forebays or afterbays to avoid spilling water on account of daily load variations?
Washington Water Power Company—See Question 8. Oregon Power Company—Yes.
Portland Railway, Light & Power Company—Every fore-bay is of value in carrying our load, which has less than 100% load factor. We have two hydro stations with forebays which are of special value in carrying less than 100% load factor loads.
6. Have you any information of the effect of bucket wheel renewals in efficiency, and can you throw any light on the problem as to when it pays to replace buckets to maintain efficiency?
Oregon Power Company—This company operates two 18-inch double horizontal Victor turbines in its Albany Plant under a mean head of 48 feet. Quite frequently the buckets are broken out and the efficiency of the wheel considerably reduced, according to the number broken. We find that it is best. to rebuild the buckets by welding. If this is not done there is considerable water thrust on the bearings which has a tendency to spring the shaft, making it necessary to replace the runners in course of a very short time.
Portland Railway, Light & Power Company — Possibly the question refers to impulse wheels. In case turbine wheels are referred to, we have no tests to show effect on efficiency and as a basis for changing wheels. Have experienced trouble with buckets of turbine wheels wasting away on back side in a number of instances. This is a serious trouble.
7. Have you had any wheels, nozzles or buckets replaced by other or improved design, and if so, what data have you on the betterment?
Oregon Power Company—This company is now contemplating the installation of new runners in the wheels referred to in the preceding question, with a more improved type. The manufacturers of the wheels have supplied us with data to show that the new runners will increase the capacity of the wheels 10 per cent at an expense of $10 per horsepower for the increase.
Portland Railway, Light & Power Company—Wheels replaced gave trouble from breakage of turbine buckets. New wheels have no trouble.
8. Can you give data on other hydraulic economies of general interest?
Washington Water Power Company — There are four plants on the same river which is fed from a lake of about 45 square miles area with a controllable depth of about 6 feet. The plants are in the following order: Commencing from the lake, Post Falls, Spokane, Long Lake, and Little Falls. After the spring flood water is passed the controlling gates and bear trap dams at Post Falls are closed and as far as possible only sufficient water is passed through the Post Falls plant to enable the other plants to carry the proper load without losing any water over the dams. The problem is complicated by the time element of flow between the plants and by the necessity of furnishing sufficient water for operation of the city's pumping plant and the Inland Empire Railway Company's power plant. Water cannot be conserved at Long Lake, as that plant is. only equipped for an output of 25% of its ultimate capacity.
Questions 4, 6 and 7 are not answered, as presumably they refer to impulse wheels, and we do not use any.
TRANSMISSION AND DISTRIBUTION ECONOMIES
1. What percentage of your total energy generated is sold to consumers?
Washington Water Power Company-78.1%, approximately.
Oregon Power Company-72%, approximately.
Portland Railway, Light & Power Company-76.3%, approximately.
2. Of the difference between the two, do you know how much is lost in your transmission system, and how much in your distribution system; that is, have you sum' totals of metered energy passing through your distribution substations? 3. Washington Water Power Company—No information is given as to the differentiation between "Transmission" and "Distribution," but for the purpose of furnishing the information asked for the low voltage feeders from the power stations and substations in Spokane were considered "Distribution Lines," and all others were considered as "Transmission Lines."
The losses there are as follows, approximately:
In Transmission System, 59.3%.
In Distribution System, 40.7%.
Oregon Power Company-18 per cent in transmission system and 10 per cent in distribution system.
Portland Railway, Light & Power Company — Loss in transmission, 7.9%. Loss in distribution, including 600 volt railway and other conversions, 15.8%.
4. What steps have you taken to reduce transmission and distribution losses, and what results do you estimate from such steps?
Washington Water Power Company—As yet none. Owing to power plant over-development the losses have not been such as to justify any capital expenditure to reduce them. Considerable expenditure is now being made to improve regulation by increasing line conductivity and this will of necessity decrease the percentage loss.
Oregon Power Company—We have provided disconnecting switches so as to remove certain step-down and step-up transformers during the light load period, so as to overcome excessive transformer charging current. This will result in a reduction of 25% in transmission losses.
Portland Railway, Light & Power Company — We endeavor to maintain balance between economy and cost.
STEAM PLANT ECONOMIES
1. What number of kilowatt hours per barrel of fuel oil do you obtain from each or any of your steam plants, giving brief description of plant and load conditions?
Portland Railway, Light & Power Company—Plants under standby mostly. Burn sawmill refuse (hog fuel) principally. Fuel oil used only in emergency and have no data on fuel oil alone under running conditions.
2. Does it pay to test fuel oil when purchased for gravity, percentage of moisture and calorific value?
Oregon Power Company—Yes.
Portland Railway, Light & Power Company—We never have confined ourselves to test specifications.
3. Have you any definite data on the percentage of steam used in atomization of fuel oil?
Oregon Power Company-0.529 lbs. steam per lb. oil. Portland Railway, Light & Power Company—No.
4. What has been your experience with heat insulation of boiler settings?
Oregon Power Company—Properly insulated boilers will effect saving of 20 per cent.
Portland Railway, Light & Power Company—Have had no trouble. We use ordinary settings.
5. Do you use economizers, and if so, what feed water temperatures do you get ingoing and outgoing?
Portland Railway, Light & Power Company—One plant has economizers. Ingoing feed water, 164 deg. F. Outgoing, 240 deg. F.
6. Have you had any experience with automatic control of dampers, fuel oil supply, etc.? If so, with what results?
Oregon Power Company—This company has installed la its Springfield plant one Mason regulator which gives entire satisfaction.
Portland Railway, Light & Power Company—No.
7. Have you modified your furnaces to improve efficiency, and if so, with what results?
Oregon Power Company—We found from tests that it Is best to have as large a space as possible between the grate bars in order to increase the draft area. This not only increases the capacity of the boilers, but it also helps to keep the grate bars cool. We also find that it is best to install hollow rest bars under the grate in the ovens, which allows a constant circulation of water through the rest bars. We also keep a constant supply of water in the ash pits. The condensation of this water has the effect of keeping the carbon deposit on the grates soft so that same can be removed easily when the clinkers are raked.
Portland Railway, Light & Power Company—Furnaces arranged to get best results using hog fuel regularly and fuel oil in emergency.
8. Have you any fuel oil burner that you consider superior in the matter of efficiency. If so, give data.
Oregon Power Company — Inside mixer burners such as the Hammel have given good efficiency in our Springfield generating station at Springfield, Oregon.
Portland Railway, Light & Power Company—The Hammel burner does very well under our conditions.
9. To what extent does it pay to equip your fireroom with indicating or curve-drawing instruments, such as draft gages, flow meters, pyrometers, temperature recorders CO, indicators, etc.?
Oregon Power Company — In modern power plants the installation of the above instruments is a necessity.
Portland Railway, Light & Power Company—It pays to the extent that the data shown by the instruments affects the practical and efficient operation of the plant. We favor most of the instruments enumerated for a plant which runs continuously during any period.
10. What is your opinion on steam versus electric auxiliaries, with special reference to heat balance, assuming the use of feed water heaters?
Oregon Power Company—We favor steam auxiliaries.
Portland Railway, Light & Power Company—Should use some steam auxiliaries with feed water heaters, but prefer electric drive for most of the auxiliaries.
11. How high a vacuum do you carry, and is this measured at the turbine discharge or at the vacuum pump suction?
Oregon Power Company-28-inch, measured at turbine discharge.
Portland Railway, Light & Power Company—Carry 29 inch, measured at turbine discharge.
12. Have you experimented with steam lanes, baffles, etc., in your condensers, and if so, with what results? Portland Railway, Light & Power Company—No.
13. Have you any data on improvement of vacuum to be obtained by increasing your circulating water supply, and relative costs and benefits to be derived?
Oregon Power Company—This company has installed in its Springfield generating station at Springfield, Oregon, a Worthington 21/2-inch two stage Hotwells pump for a condenser for a 2000 kw. General Electric turbine. An investigation into this matter shows that much better results can be obtained by the replacement of this apparatus with a Radojet Air Pump. This equipment would not only occupy much less floor space, but would be considerably more efficient.
14. What economies of fuel or increase of efficiency have you been able to obtain in your steam plants by other means than those mentioned above, giving particulars?
Oregon Power Company—Under ordinary conditions this company uses sawdust, planer shavings, slabwood and mill refuse in its Springfield generating station, and we find that by making the fuel distributing system over the boilers automatic and by feeding a certain supply of fuel constantly on the fire that much better results can be obtained. Before this automatic device was installed we would fill the ovens with fuel, and this practice was found to result in the decrease of the efficiency of the boilers until such time as the fuel would burn to the point where the maximum heat was obtainable. Under the arrangement now in effect the fuel is always at red heat. Portland Railway, Light & Power Company—See answers to other questions.
F. D. Nims explained that in utilizing powdered coal better results are obtained from the poorer grades. In using hogged fuel 400 kw. hr. are obtained per unit (200 cu. ft.) An ordinary sawmill produces about one unit per thousand feet of board cut.
L. M. Klauber, San Diego Consolidated Gas & Electric Company, described an automatic system for controlling hot oil flow which cost. much less and is nearly as effective as more expensive installations. He advocated constant use of soot blowers and tube cleaners in boilers and an air and water cleaning spray in condenser tubes.
John R. Brownell of the California Industrial Accident Commission stated that the life of the boiler may be prolonged by water treatment instead of cutting the scale.
S. J. Lisberger described a simple device for determining the salt content of boiler water; a maximum of 50 gms. per cm. being allowed.
IRON AND STEEL CONDUCTORS
R. C. Powell's paper (p.338) was summarized by S. J. Lisberger, who pointed out that iron wire can economically be used for small loads, but that stranded cable has less reactance with heavier currents and can be used for guy wire in the future.
L. M. Klauber stated that the San Diego Consolidated Gas & Electric Company has built 300 miles of steel conductor line, using it tc advantage (1) for long spans requiring high tensile strength, (2) lightly loaded main lines of moderate length, (3) for 2300, 6600 and 11,000 volt branch lines, (4) series circuits. He believes that those who have used it will not go back to copper, regardless of price, because the ratio of copper to steel prices will probably be the same. Much of the construction is with 700 ft. spans and 40 ft. poles with 4 ft. triangular clearances. Two poles are used for spans of over 1000 ft., no poles being placed in any stream bed, no matter how dry. Single galvanized steel cable corrodes, but extra galvanized has an indicated life of 15 years in salt air. A special device is employed for painting long spans every two years.
Standardization of Pin Type Insulators
Discussion of the committee report on "Standardization of Pin Type Insulators" (p. 333) was introduced with the following written communication:
J. P. Jollyman: The committee has recommended the use of the higher efficiency types of insulators for Class 4 and Class 5 service after calling attention to the advantages of this type as compared with the older or standard types.
The higher efficiency type, while in many ways much better than the standard types, has two characteristics which are not as good. First, it has a lower striking distance. Second, it has a lower effective surface resistance. The lower striking distance gives the insulator a greater factor of safety against puncture and this may be a valuable characteristic in districts where lightning is frequent and where the older types are liable to puncture. In districts subject to heavy fogs or other conditions leading to the liability of flashover from excessive surface leakage, the shorter striking distance may be a disadvantage.
While the method of computing the true relative surface resistance of insulators has been generally known since it was given by Mr. A. O. Austin in his paper on suspension insulators in Proceedings A. I. E. E., Vol. 30, 1911, the manufacturers have never given this function in their catalogue data but continue to give "leakage distance," which is not a true basis of comparison.
Considering the two types of 27 kv. insulators illustrated in the report the following comparison will serve to illustrate the points mentioned:
In items 4 and 5 the effective surface was considered as ending when the lower end of the petticoat next to the pin was reached in the higher efficiency type and when a point 1 inch from the pin thread was reached on the inside surface of the center of the standard type. The surfaces beyond those considered above are so close to the pin as to be ineffective under the conditions when surface leakage becomes important.
It must be conceded that the higher efficiency type will not lose effective leakage surface due to tilting on the pin, whereas the standard type may lose most of the surface on the inside of the center due to this trouble. Such a condition will reduce the effective surface resistance of the standard type to 86% of the surface resistance of the higher efficiency type.
Flashovers of insulators sometimes take place when conditions giving rise to excessive surface leakage occur. Heavy fogs, especially near the sea coast, and possibly the sudden formation of dew, give rise to surface conditions which permit high leakage, and this is sometimes followed by a flashover. Where such conditions occur a type of insulator having a high surface resistance and a long striking distance should give superior service. In bringing out their higher efficiency designs the manufacturers have improved their insulators in many ways, especially mechanically, but have not greatly improved their surface leakage characteristics. It is these characteristics that are most important where lightning is infrequent and surface conditions are bad.
It does not appear that the higher efficiency types of insulators are much, if any, better than some of the older types from the standpoint of their ability to resist flashover under favorable surface conditions.
P. M. Downing stated that no close relationship exists between standardization of line voltage and standardization of insulators. For example, a 60,000 volt insulator in some situations is not suited for 11,000 volts under other conditions. Catalogue classifications should be based on duty to be expected from an insulator under given climatic and operating conditions.
C. O. Poole, in response to a question by S. J. Lisberger, advised that the Southern Sierras Power Company has used higher efficiency insulators. A reduction of leakage surface corresponds to a like reduction of efficiency. He prefers designs having large open apace between petticoats. He suggested that the standardization of voltages instead of insulators would make the manufacturers' problem easier.
L. M. Klauber reported that the San Diego Consolidated Gas & Electric Company was using higher efficiency insulators in localities exposed to salt spray and had experienced no flashovers or break-downs in two years time. With regard to the large number of types of insulators available for the same service, he brought out the point that fewer types would make possible lower prices.
G. I. Gilchrest, research engineer, Westinghouse Electric & Mfg. Co., contributed the following written discussion:
The standardization of pin type insulator designs based on the diameter of pinhole, height and type of pin and overall dimensions of the Insulator, appears logical. An opportunity is thus given the insulator companies to deviate in the details of design and to add improvements in the insulators which appear feasible as the insulator art advances.
The Standardization Committee of the American Institute of Electrical Engineers is considering the standardization of transmission line voltages. Any standardization of pin type insulators will eventually be based upon the finally accepted transmission line voltages. If the insulator manufacturer could then include all the standard designs under one general type, the material advantages would be gained by both the producer and the purchaser.
The line voltage ratings listed in the insulator catalogues represent what is considered good practice in localities having favorable climatic conditions. The dry and wet flashover voltages and line voltages specified by one manufacturer on a particular design often vary from 20 to 25 per cent from the values specified on the same design by another manufacturer. This deviation is due to the methods of test used and to the factor of safety assumed by the manufacturer, rather than to any inherent properties of the porcelain body.
It would appear that the line voltage ratings of a manufacturer's standard line of insulator designs should be based on a summation of operating results that could be furnished by transmission engineers and which represent the line voltage ratings that they consider good practice in localities which afford fairly severe climatic conditions. Furthermore, from a general consideration of the problem of insulator application it would seem that each insulator design should be recommended as a standard at two or possibly three line voltages, depending on the climatic conditions involved. For example, a unit rated by the manufacturer at 33,000 volts might be standardized as follows:
(a) To be installed on 44,000 volt lines that are located in sections where lightning storms are practically unknown, wooden construction is used and the air is clean and dry.
(b) To be installed on sections of 33,000 volt lines where the climatic conditions are fairly severe and steel construction is used.
(c) To be installed on sections of 22,000 volt lines where the climatic conditions are unusually severe and steel construction is used.
Likewise, a design rated by the manufacturer at 44,000 volts might be recommended for 33,000, 44,000 and 55,000 volt service. Of course, the type of customers served, etc., have a very important part in determining the factor of safety that should be used on any section of line. If the units are designed so as to overlap in this manner the problem of maintaining the desired service on all sections of the system should be partially solved.
The larger transmission companies can afford to maintain an engineering staff that recommends the proper insulator for every section of line. However, the smaller operating companies which represent a considerable proportion of the power supply of the country, depend upon the catalogue ratings, the salesman's recommendation and the existing practice of the larger transmission companies. Therefore, line voltage ratings based on operating experience would be a material benefit to the transmission companies in general and would tend to minimize the number of unsatisfactory installations that are caused by using an insulator design which has too low a factor of safety. Moreover, a standardization of transmission line voltages and a standardization of methods of test used by insulator companies to obtain flashover ratings of the insulators would doubtless make the problem of insulator standardization less complex.
H. S. Perkins (contributed): The recommendations for 6600 volts and 11,000 to 15,000 volts, coast districts, in Table 7 of the report, while based on the consensus of opinion in this territory, might be slightly modified in design so as to also meet the needs of other sections.
The 6600 volt type is designed with a petticoat whose inside diameter too closely approaches the outside diameter of the pin to allow safe operation. The air-gap, or striking distance, between the pin and the lower edge of the skirt will replace all 11 to 17 kv. types used for 6 to 8 kv. severe service on the coast.
The same objection as to ineffective surface insulation applies to the type recommended for 11,000 to 15,000 volts. coast service. These objections are met by a new insulator of more efficient design (Fig. 2) which should supersede the older type.
This proposed insulator has the same exterior dimensions as that recommended, thus allowing the use of the same pin length. Its thicker porcelain allows a higher flashing potential by its reduction in charging current. Its surfaces are arranged to take the proper proportion of voltage stresses under varying weather conditions: Its greater mechanical strength allows increased pole spacing.
Insulator manufacturers will gladly co-operate with the committee in putting these recommendations into effect and thus bring about a reduction of the number of types in use.
SUBSTITUTE FOR CEDAR POLES
The discussion of L. M. Klauber's paper on "Substitute for Cedar Poles" was opened by R. E. Cunningham of the Southern California Edison Company with the following paper:
As Mr. Klauber's paper leaves open the question of length of service to be obtained from Douglas fir, it is possible that some definite idea can be obtained from the report of the U. S. Department of Agriculture Forest Service on experiments with Western yellow pine. I understand that the Western yellow pine has much the same characteristics as Douglas fir.
In 1906 the Forest Service began a test on the treatment of poles, known as Project L-34. A large number of cedar and yellow pine poles were treated in an experimental plant installed at Wilmington, California, and these poles were set in regular line construction by a number of power and telephone companies, reporting back to the government date and location where poles were set. The following is a complete copy of the last progress report covering the experiment on yellow pine poles, which I believe is of special interest to us at this time. By the government's report it would appear that hot creosote open tank treatment will preserve the butts of the poles a reasonable length of time, but some method should be adopted for preserving the portion of the pole above ground.
"REPORT ON SPECIAL PINE POLES"
The Western pine poles Installed in and near Los Angeles under this project comprised a special shipment of 81 35-foot poles cut at Pine Ridge, Madera County, California, in summer of 1906. They were to be used in trying out a new apparatus designed to treat only the butts under pressure. Upon trial this apparatus was found to be impracticable because it could not be made to prevent loss of preservative through season checks in the poles. Forty-eight of them were therefore given the ordinary open tank treatment with carbolineum.
After treatment the poles were distributed among the six co-operators in Los Angeles. Subsequently the U. S. Long Distance Telephone & Telegraph Company became a co-operator by taking over most of the experimental poles owned by the Home Telephone Company. Nearly all installations were made in 1907-1908, three being recorded as set in 1909.
A few of the poles were carried away by floods, one was broken in moving and twelve have since been removed because new construction required higher poles. The total number included in this report is fifty. The result of the inspection is as follows:
This table includes all of the carbolineum brush treated poles in the experiment, and all untreated poles for which there were setting records, except such as were destroyed by floods. The average life of the poles treated with carbolineum was five years and two months. This includes two which were set in concrete and which remained in service two years and four months longer than any of those similarly treated and set directly into the ground. With these two omitted, the average life was four years and five months.
The untreated poles gave an average service of three years and six months. This includes one set in concrete which remained in the line three years and two months longer than any untreated pole in the experiment set directly into the ground. Two others set in concrete lasted four years and eight months and five years. With these poles omitted, the average life was approximately three years.
Though all of the poles treated with creosote by the open tank method are sound below ground, I. e., in the portion treated, nine show serious decay in the tops. One untreated pole which was stubbed when rotted off shows serious top decay. One which failed before 1912 and which had been attacked by woodpeckers, was decayed below the nest. At least two of the untreated poles were attacked by insects below the ground line, decay being hastened considerably thereby.
E. A. Quinn said that the San Joaquin Light & Power Corporation is using Port Orford cedar instead of treated poles. Tamarack pine poles, given an open tank butt treatment, and put in the ground in 1908 with 33 lbs. of creosote per pole, all had to be stubbed within five years.
C. O. Poole cited satisfactory results with lodge-pole pine poles treated in a temporary portable tank in 1908. Although no penetration was perceptible after 24 hours boiling, yet 600 poles thus treated lasted nine years.
S. J. Lisberger reported that the Pacific Gas & Electric Company is using concrete reinforcing stubs, as is likewise the .Pacific Telephone & Telegraph Company. Stubbed poles that have been in service three or four years are still as good as ever. This affords material relief from the shortage of poles and reduces the cost of labor.
E. R. Northmore of the Los Angeles Gas & Electric Company has concluded that concreting old poles does not pay because the rot follows up to the top of the concrete. He prefers treated stubs.
L. M. Klauber believes that concrete stubbed poles which have been in service at San Diego for nine years are as strong as when first put in. There is no danger in this method if all the old rot is cut out and replaced by a 4 to 6 inch concrete collar with mesh reinforcing. At present prices of 30 cents a foot a new pole costs about $50' to set in place, including labor, whereas $7.50 will pay for reinforcing.
INSULATOR DETERIORATION
The report of the committee on insulator deterioration as presented by Mr. John A. Koontz, brought forth no important oral discussion. Several written contributions were received, as follows: H. Michener: The experiences with suspension insulator depreciation on the lines now constituting the system of the Southern California Edison Company, are set forth in Table 1. The great majority of the defective insulators were found by the megger. These figures do not indicate any law of depreciation. This may be because there is no such law, or because the megger is not a reliable instrument for picking out the defective insulators. Of the insulators tabulated in Table 1, the approximately 185,000 located on the first eleven lines listed can be designated as type "A." These insulators are of the single piece, 10-inch diameter type, having pin and clevis hardware, grooved head and pin hole, cement entirely surrounding the head and upper end of pin, and no gasket to prevent lower edge of cap from bearing on the porcelain.
The approximately 50,000 insulators, located on the remaining eight lines listed, are all of the single piece, 10-inch diameter type, but the distribution of those having different detail characteristics is not known by the writer.
The insulator referred to as type "B" is similar to the type "A," with the following exceptions: The cement that holds the cap extends only a short distance up the side of the head of the porcelain; the lower edge of the cap is separated from the porcelain by a gasket; and the cement does not extend across the upper end of the pin.
Table 2 shows the results of megger, oscillator and high potential tests on 10,000 type "A" insulators removed from the Fernando-Saticoy line. As a means of getting the best possible service from this line, all these insulators were removed and replaced by type "B" insulators. This case is cited primarily to show the loss which may occur from handling. Part of these insulators were crated in the standard shipping crates before being shipped to the testing yard in Los Angeles. The remainder were hauled in trucks in strings of three or six units without being crated. Table 3 shows the comparative results of these two methods of handling the insulators.
Table 4 shows some comparisons of the depreciation of dead end insulators and of suspension insulators.
The foregoing has dealt with insulator depreciation as indicated by tests. Table 5 shows the insulator failures which have occurred on this system during the past 15 months. These figures would be much more illuminating if the respective numbers of the dead end and the suspension insulators in service could be given. However, they do show that the greater number of failures occur on dead end insulators. But it must be borne in mind that at least part of this difference between the number of failures occurring on dead end insulators and on suspension insulators is due to the grounding of the insulator hardware on dead end insulators.
This company has now arranged to make much more complete reports of the insulator tests and insulator failures, with the hope that the information thus gained will be of some benefit.
H. S. Perkins: Insulator depreciation due to rapid changes of temperature can be lessened by using thicker porcelain than is found in the ordinary type of suspension insulator and by employing a white glaze. Thick porcelain gives greater dielectric strength, higher corona break-down point and retarded temperature rise in interior parts of the insulator. The white glaze reflects the heat rays and particularly prevents their absorption by the insulator. Experiments with black, brown and gray glazes definitely prove that the gray glaze absorbs heat more slowly, and consequently the insulator is subjected to less rapid changes in temperature. It may also be beneficial to paint the hardware with aluminum paint.
Geo. M. Wills: When the insulator testing work of the Southern Sierras Power Company was started a year ago it was without precedent or past experience of other companies to follow. Being equipped with a 110 or 120 kv. 60 cycle transformer and a 110 to 125 kv. 200,000 cycles oscillator, it was first decided to give each insulator unit a 30-second test with the 60 cycles flashover and 15-second test with flashover voltage from the oscillator. It was soon found that most of the bad units were discovered soon after the application of the stress and that a continued application of flashover voltage caused units to break down that apparently had some Insulating value left in them. It was finally decided to discontinue the use of the 60 cycle voltage and to establish a routine test of 5 seconds application of the flashover voltage from the oscillator. This test will locate a very large percentage of the bad ones with an expenditure of a minimum amount of time.
We have observed that our regular suspension type insulators with a 10-inch disc require a voltage of about 80,000 to flash over.
From the records made while testing at the steam plant with both 60 cycles and oscillator we find that while testing with the oscillator first we examined 716 units, of which 187 bad units, or 26 per cent, were found with oscillator, after which 113 more bad units, or 15 per cent, were found with the 60 cycle test. While testing with 60 cycle first we examined 897 units, of which 361 units, or 37.8 per cent, were found to be bad, after which 123 more bad units, or 12.8 per cent, were found with the oscillator test. While this would indicate that the 60 cycle test was more effective, it must be borne in mind that the 60 cycle test was for a period of 30 seconds and the oscillator for only 15 seconds. Later, while in the neighborhood of control station, we examined 198 units first with 5 seconds 60 cycle test, finding 1 bad one, after which a 5-second oscillator lest was applied to the same units, finding 24 bad ones, or 12 per cent. This result is quite different from the results obtained at the steam plant.
Again, while at the steam plant, we examined 983 units with the H. T. megger, finding 80 units, or 8 per cent to be bad. When these units were subjected to a combined test of the 60 cycles and oscillator, we found 48 per cent to be bad. Later, while at Inyokern we tested 357 units first with the megger, after which they were given the regular 5-second oscillator test. 'The megger showed them all to be good, but the oscillator found 206, or 57 per cent, to be bad. This result illustrates how inadequate the megger is for insulator testing. The insulators at the steam plant probably had sufficient moisture in them to permit the megger to give a reading, while the bad ones at Inyokern were so dry after a hot summer that they all measured "infinity."
To date we have examined a total of 47,989 units from the line, of which 12,439 units, or 26 per cent, have been found to be bad. So far the insulators have been found to be in the worst condition in the neighborhood of Inyokern, where we tested 471 units, of which 243, or 51 per cent, were bad. The Insulators which have been in the best condition have come from the neighborhood of control station, from which in one week, we tested 1730 units, of which 158, or 9 per cent, were bad.
We have made observations to determine whether insulators coming from one arm were in any worse condition than those coming from another. The results obtained were as follows:
The results were so close that they may safely be called alike from all arms. We have also reviewed our records to determine if the position of the unit in the string had anything to do with its being bad. From the records of nearly 6000 bad ones, we have the following:
Again we have observed that there is very little difference between dead-end and suspension towers as far as bad insulators are concerned. This is shown by the following:
We have found that a great majority of the insulators fail through cracks in the head of the unit, break-downs occurring between the end of the pin and the inside of the iron cap. Only about 5 per cent of the failures have occurred through punctures outside of the iron cap. Most of these failures have occurred through original defects in the porcelain. We have not found that failures have occurred any more frequently among insulators of dark than of light color, color being an indication of the extent of firing.
