Motion Picture Herald (Mar-Apr 1945)

The Show Must Go On... AND DOES with a Robin-Imperial STEDYPOWER (Built by Imperial Electric Co.) The best means of avoiding arc power failures which aggravate patrons, make refunds necessary, and fine chairs, air conditioning and good pictures meaningless. Designed specifically for use with direct current high intensity arcs — that screen light source which is essential to the proper projection of Technicolor pictures, and a safer, higher level of auditorium illumination. Not just a motor-generator but a guarantee of service — a power plant with 55 years' electrical know-how and 35 years' theatre experience "built in." Liberal over-load capacity. Quiet operation. Voltage holds constant during change-overs. Built in all ratings and combinations. Your Independent Theatre Supply Dealer will help you make application for a STEDYPOWER if yours is one of the many theatres now qualifying. Write for literature. J. E. ROBIN, INC. 3 3 0 W. 42™ St., New York City Motor-Generators and Motors for Every Requirement WAYS & MEANS in operation, installation, maintenance John J. Sefing is a graduate mechanical engineer and has long specialized In theatre work Are Your Theatre Illumination Costs as Low as They Might Be? what with curfews and brown-outs to save coal and electric power, we are — or should be — pretty conscious of the necessity to eliminate waste, or at least reduce it to a minimum. But waste is never good, and few businesses can long stand much of it. Since the theatre lives on light, its lighting methods should be checked for the most economical operation and maintenance under the circumstances. And right now this may mean the toleration of less effective illumination. The lighting scheme and especially the fixtures installed should allow in many cases, under present restrictions, a lower demand load charge, reduced cost of current, use of less current for the required illumination, longer life of the lighting equipment and of lamps. One thing in theatre operation that is quite frequently misunderstood is how electricity must be paid for either by a "demand" or "peak load" method of calculation. All this means in a general way that charges must be paid on the current available at the theatre, whether it is used half an hour per month, or twenty-four hours per day for 30 days per month, together with a certain charge for the total amount used. These extra charges, besides the cost of the current used, are known as demand or meter charges, and are figured at so much per kilowat on the peak usage reached at any one time during the month. Now if the theatre lighting system is wired for, say, 10,000 watts, a demand is created of 10 kilowatts. One kilowatt equals 1,000 watts, and electricity is sold by the kilowatthour. If this maximum load of 10,000 watts is used for just' one hour a month, that demand of 10 kilowatts has been created on which there will be a monthly charge of so much per kilowatt. This charge is made because the electricity is available in the electric lines and can be used at any time and at the full capacity of the lighting system. Plainly, then, how well the lighting system is designed, and how efficient are the fixtures installed, importantly effect the cost of the lighting expense of the theatre. In further illustration, let us suppose the lamps in the lighting system were used only five hours during the entire month, and that they burned 50 kilowatts at a charge of 3<f; per kilowatt (the cost of the current used in this short interval). Now if these same lamps 14 were used, say, ten hours per day, 30 days per month, that would be 100 kilowatts per day, or 3,000 kilowatts per month. The cost would be $90. And to this cost would sti' be added the demand load charge of so much per month. Electricity is paid for in theatres also ac cording to the increase in the cost of tb current throughout a certain bracket, or specified minimum of kilowatts used pe< month. This cost is based on the peak loa< used the previous month, or so much pe ampere, or horsepower, or wattage needec for use. However, regardless of what the rat is, whether it is \§ or 10^, the established demand rate must be paid at fixed charges For example, a theatre has four hundra 25 watt lamps, which means that each lam will burn 25 watts per hour of illumination Accordingly, 10,000 (25x400) watts, or 1 kilowatts, must be available at all times ii order to use these 400 lamps, and for this demand load charge will be paid. Now if 10,000 watts are available in th electric line service, a fixed demand load i created which may run in some cities to abou $2 per kilowatt. In the above case, and wit the assumed figures, about $20 would hav to be paid, this amount in addition to th charge for the amount of current actuall used by the lamps. EFFICIENCY OF FIXTURES In checking the lighting system it shoul be made certain that only the most efficier fixtures are used and that they are constantl maintained in order to get the highest outpi of illumination for their rated capacity Fixtures that are improperly designed c wrongly installed, and that use lamps c higher wattage than necessary for the lightin job, waste electricity. Fixtures that are ol and of an absolete type should be replaced ; the first opportunity with fixtures that ha-\ efficient reflectors, and perhaps glass roundel permitting the highest transmission of ligl even with lamps of small wattage. The ii stallation of efficient low-wattage reflectc fixtures in theatres having over-loaded lightir circuit troubles may prove a conveniei remedy. In any case, overloaded lighting ci cuits should be corrected for they cause n> only fires, but also repeated fuse renews In existing lighting installations not readi BETTER THEATRES, APRIL 7, 19