Moving Picture World (Nov-Dec 1923)

844 MOVING PICTURE WORLD December 29, 1923 The Manufacturers of Independent Generating Plants Take the Floor IN our last issue appeared an article on the independent generating plant in which the subject was treated from the ‘‘cost of operation” point of view. A previous article, devoted to this branch of equipment, brought forth many letters from exhibitors, from which we made extracts on which we commented last week. This time we are giving the floor to four manufacturers who have expressed their views on last week’s installment. It will be noticed that, while two of these regard our estimate of 15% for depreciation as being too high, they differ on other points. One, indeed, recommending the utilization of alternating current, appears to be rather reactionary. One manufacturer approves a storage battery installation, while another opposes it. What They Say One manufacturer writes : Fifteen per cent, depreciation, in our experience, is too high. Ten per cent., we believe, is a fairer figure. Another backs up this recommendation with the following : It is entirely safe to figure your deprecia SPECIAL ROLL TICKETS Your own special Ticket, any colors, accurately numbered ; every roll guaranteed. Coupon Tickets for Prize Drawings; $5.00, $6.00. Prompt shipments. Cash with the order. Get the samples. Send diagram for Reserved Seat Coupon Tickets, serial or dated. All tickets must conform to Government regulation and bear established ^price of admission and tax paid. SPECIAL TICKET PRICES Five Thousand $3.00 Ten Thousand 5.00 Fifteen Thousand 6.50 Twenty-five Thousand 9.00 Fifty Thousand 12.50 One Hundred Thousand 18.00 National Ticket Co. shamokin, pa. THE CINEMA NEWS AND PROPERTY GAZETTE 80-82 Wardour St W. I. London, England Hu the largest certified circulation at the trade in Great Britain and the Dominions. All Official Notices and News from the ASSOCIATION to its members are published exclusively In this Journal. YEARLY RATEi POSTPAID, WEEKLY, $7.3 SAMPLE COPY AND ADVERTISING RATES ON REQUEST Appointed by Agreement Dated 7/8/14 THE OFFICIAL ORGAN OF THE CINEMATOGRAPH EXHIBITORS' ASSOCIATION OF GREAT BRITAIN sad IRELAND. LTD. tion on the basis of ten per cent, per year, which will wipe out the entire investment in a ten-year period. and then goes on to discuss the cost of operation as follows : With reference to operating expenses, would state that you have figured this high enough, as the fuel consumption should not exceed 1-10 gallon per horsepower hour and .001 pint of lubricating oil per horsepower hour. Basing our figures on the present price of gasoline, which is approximately 1G cents per gallon, and lubricating oil at $1.00 per gallon, you would have a cost of 4.2 cents per K. W. hour for fuel and lubrication. Now, assuming that your requirements are 7% K. W. per hour, your cost would be 29.6 cents per hour, or $1.48 for five hours’ operation, or a cost of $539.38 for five hours’ operation 365 days of the year. From what we have been able to learn, there are a great many houses that are operating with less than 7% K. W.; in fact, many require less than a 5 K. W. plant, and the real small houses probably could get along very nicely with a 2% or 3% K. W. outfit. Approves Storage Batteries A third manufacturer writes : There is no doubt but what an independent plant with*storage batteries would be the ideal equipment, using a motor generator set to transform the current from alternating to direct for the apparatus and motors whenever the public service current is available as a stand-by. Advises Alternating Current While the fourth manufacturer offers many valuable suggestions, we do not agree with that advising the utilization of alternating current, which all progressive exhibitors are now converting into direct whenever possible for projection purposes. With this comment, we quote from his communication as follows : You have assumed that the carbon arcs must be operated in parallel. The arcs may be connected in series when a 110 volt plant is used so that no additional current will* be required when the two arcs are being operated. As you know, the carbon arc operates at approximate 55 volts. When one arc is being used, the voltage is reduced to approximately 55 volts by means of a rheostat. If the two arcs are connected in series, the second arc is simply taking the amount of current which was used up in the rheostat so that no additional current is required. You recommend the installation of motor generator sets to convert the alternating current to direct current for operating direct current motors, fans, etc. As a general rule, we do not believe that this will be advisable where the independent plant is to be used for emergency only. We believe that it would be better for the exhibitor to either install an alternating current plant or to install a direct current plant and use a converter for changing the direct current to alternatingcurrent for operating the standard equipment during emergencies. Cost of Battery Considered The 110 volt storage battery would not be economical. The original cost of a 110 volt storage battery would be just as great, if not greater, than the extra cost for a large plant and the depreciation would be considerably greater. For example: The 7% K. W. plant lists at $1,200, the 10 K. W. at $1,525, and the 15 K. W. at $1,800. The 110 volt storage battery of suitable capacity would run from TYPHOON COOLING SYSTEM TYPHOON FAN CO. w 345W.39-ST. ^ NEW YORK NEW YORK $700 to $800. It would also require a more expensive switchboard, which would add to the cost of the plant. If an exhibitor wants an individual plant for emergency use only, then it would be best for him to install an alternating current plant or to install a direct current plant and a converter to change the current from direct current to alternating current. • For Permanent Usage If he wanted a plant for permanent use, then the most economical plant would be a 32 volt direct current plant. The Mazda projecting lamps are made in 600 watt 30 volt and 900 watt 30 volt. Therefore, a 32 volt plant will make a more economical installation than a 110 volt, and right here is where a storage battery could be used to advantage, because the cost of a 32 volt storage battery is less than one-third the cost of a 110 volt storage battery. Suppose this customer was using the 900 watt 30 volt lamp. Assuming his light load to be about 850 watts during hte time that the picture machine is operating; then his light load, motor load, and one projecting lamp would be approximately four kilowatts. A 4 K. W. 32 volt machine with a storage battery would handle the requirements because the battery could be relied upon to handle the load during the change from one reel to another. The cost of a 4 K. W. 32 volt plant with a suitable battery would be in the neighborhood of $1,000. Reducing 'Wattage Requirements The reason that a 110 volt, direct current plant would not be economical would be due to the fact that so much current is wasted in reducing the voltage down from 110 volts to 30 volts. The 30 volt 900 watt lamp consumes 30 amperes. Therefore, the lamp alone would require 3,300 watts where 110 volt direct current was used, whereas it only requires a little over 900 watts where the 32 volt plant is used. The difference goes up in heat. As suggested above, if the exhibitor wants to use the independent plant for emergency only, the best plant to install would be an alternating current plant, or a direct current plant with a converter to change the current from direct current to alternating current. Summing lrp the Proposition The proposition sums up in general as follows: For the theatre depending altogether on an independent plant, the direct current plant is, as a general rule, the best proposition. Where the Mazda lamp is used and the total load does not exceed 4 K. W., the 32 volt plant is the most economical equipment. If the carbon arc is used, either the 60 volt or the 110 volt direct current plant may be used. The 110 volt is usually preferred on account of it being standard voltage. Direct current gives better projection than alternating current and saves the expense of a transverter or motor generating set for the carbon arc. Where an independent plant is to be used for emergencies only: First — Where there is no large motor load or large fan load, the 110 volt direct current may be used to advantage because electric lights operate equally well' off of either 110 volt direct current or 110 volt alternating current. Small motors can also be obtained which will operate from either alternating or direct current. Second — Where large motors or large fan loads are required, it is better to install either an alternating current plant or a direct current plant and a converter to change the direct current to alternating current. The above will hold true in most cases. However, it is advisable to have all the details of the electrical requirements of the picture show before making recommendations because many shows even with the same seating capacity differ radically in their electrical requirements.