Kinematograph year book (1939)

304 The Kinematograph Year Book. electricity from public supply, it is generally found that the cheapest power can be obtained by using the independent plant. In addition to which, experience has proved very clearly that the oil engine is more free from serious breakdown than a complete electrical system, including the motors, wiring, transformers and cables. Another advantage possessed by the Independent plant is that it is the most economical source of current for flood lighting and signs, and consequently the exhibitor is able to utilise to the utmost the facilities provided by the modern kinema engineer for all forms of exterior lighting which figure so prominently in all applications of kinema showmanship. Even where current is taken from the mains and the oil engine is employed only for stand-by purposes, its possession confers another benefit on the exhibitor, who is enabled in some places to obtain a concession in the public supply rates by the use of private plant to relieve the public supply of an excess load during the " peak" periods. Grossley Bros., Ltd.— One of the most popular sources of independent power supply among kinema exhibitors is the Crossley Diesel engine unit which may be relied upon to provide a cheap and dependable supply with an absence of noise, smell or vibration and with clean running and steady voltage — factors which are of the first importance in the selection of an independent plant for kinema purposes. A Crossley self-contained oil power plant will produce a supply at about Id. per unit. One or two instances bearing out this contention have been supplied. The first example is based upon a kinema equipped with a 27 H.P. engine. Here the total operating expenditure, including interest and depreciation, is under Id. per unit generated, representing a saving of 2d. to 3d. per unit compared with electricity from the public supply, which would have been incurred. In another kinema a 42 H.P. oil engine plant recently installed saves £6 per week. A third illustration of the economic functioning of a typical oil engine installation is based on figures supplied by another exhibitor who runs a 45 H.P. plant. In this case the local supply charge is 3d. per unit, and the cost per week works out to £10 lis. Od. The expenditure incurred by the exhibitor is as follows : Per unit generated, d. Fuel oil 0.48 Lubricating oil ... ... ... ... ... 0.11 Cost for fuel and lubricating oil ... ... 0.59 Including capital charge the total cost of power generation is Id. per unit, and as in this theatre consumption totals 844 units per week, the total cost of the independent plant works out to £3 10s. 4d., which shows a clear saving of £7 over the charge for the mains supply. Petters, Ltd.— Many exhibitors have discovered the practical advantage of installing a Petter Two-stroke Diesel generating set, the cost of generation for which under normal circumstances works out at something under 14d. per unit. A practical illustration of the saving experienced has been submitted by Petters on the assumption of a district charge of £2 10s. Od. per quarter maximum demand at fd. per unit metered, and taking as an example an average sized kinema in a small provincial town with a peak load of 32 kw. and a normal load of 24 kw. for 9 hours daily over a six-day week. £2 10s. x 32 kw. £ s d 6 3 1 13 weeks 54 hours x 24 units at fd. ... 4 1 0 Weekly cost 10 4 1