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1948-49 Theatre Catalog, 7th Edition, Page 346 (333)

1948-49 Theatre Catalog, 7th Edition
1948-49 Theatre Catalog
1948-49 Theatre Catalog, 7th Edition, Page 346
Page 346

1948-49 Theatre Catalog, 7th Edition, Page 346

It is also possible to locate the dimmer equipment on the auditorium floor level in a space convenient for the Chief Usher to manipulate them. This installation, however, does call for close cooperation between the projectionist and the Usher, so that the lighting cues are clearly identified. An objection to such installations is that it is not always possible for the Usher to be available at the required time.

If some form of stage lighting equipment is installed in the theatre, the dimmer installation may still be made as described previously. However, if the cost of additional personnel is not a Serious factor, the dimmer equipment should be mounted on the stage in the wings together with the panel board or a switchboard controlling the theatre and stage lighting. The conventional type of combination switchboard and dimmer bank is the most modern and eiiicient way of making this type of an installation, as all of the controls for the circuits involved in the installation can be manipulated by the switchboard operator.

Remote Control

Where adequate space for installation of manually operated equipment is not available or where the additional cost of remote operation of the dimmer equipment is not a determining factor, motor operated resistance or autotransformer dimmers provide a very desirable type of installation. This has the advantage of locating the dimmer equipment at the load centers where the electrical wiring and conduit layout is reduced to a minimum. Control stations for the remote dimming and switching operations can be located in the projection booth with multiple stations at each porthole. Additional control stations can be located in the rear of the auditorium and in the Manager's office. Obviously these control stations can be kept small in size and occupy little additional space in the already crowded projection booth.

Various types of control stations can be supplied, depending on the complexity of the lighting system and the results desired by the theatre owner. Normally a two-button momentary contact push button is furnished for each motor drive; one button causing the dimmers to move m the tibrighti' direction, the other in the Hdim" direction. The motor will operate as long as the button is held depressed or until the end of dimmer travel is reached. If this type of operation is not desirable a three-button control station can be furnished having iibrightii, tidimii and ttStop" buttons for each motor drive. Momentarin pressing the tibright" or tidim" button will initiate operation of the motor drive and it Will continue until the ttstop" button is Dressed at the desired intensity or until the end of dimmer travel is reached. In both cases limit switches are provided 011 the apparatus to stop the motor at the end of dimmer travel and prevent damage to the apparatus.

-A more elaborate type of control station can be installed using miniature dimming controls having small slot closmg levers having graduated dials so that the direction and range of travel of the


ABOVE is a typical pilot control station for motor operated dimmers in a small theatre. In theatres where there is no stage and no intention to provide any form 0! stage lighting. such cl control can be installed.

dimmer motors can be directly determined by moving the miniature dimming control. Still a further possibility is the installation of a semi-automatic control, having a number of push buttons at each station which are preset to automatically produce a definite, desired intensity. The operator in this case merely pushes the button for the desired cue and the dimmer equipment automatically runs until the preselected desired intensities are obtained, at which point the dimmer automatically stops. It is obvious that the more complex the control system, the more costly the initial installation of the apparatus.

Installing the Equipment

In selecting the location for the dimmer equipment, there are a number of considerations that should be reviewed. First of all there must be adequate ventilation to dissipate the heat generated in the dimmer equipment. This is of particular importance with resistance dimmers, but with any type of installation the ventilation should never be restricted so as to cause the dimmer equipment to exceed its normal operating tempera ture. Overheating the dimmer equipment will cause the apparatus to fail in the same manner as exceeding the rating of the dimmer.

Secondly, the area selected for the dimmer equipment should be free from dirt and dust, particularly any oily atmosphere such as might be present in a boiler room. An accumulation of dirt and dust on a moving contact not only makes the apparatus difficult to operate but also introduces the hazard of burned contacts and improper electrical connections between the moving contact arm and the stationary buttons. An electrical arc produces an extremely large amount of heat, and any condition that causes arc- n ing between the buttons and the contact shoes will rapidly burn out the dimmer unit.

Finally, the location should be selected where the apparatus will be accessible for ready inspection of the contacts, lubrication of the moving parts, and periodic cleaning and servicing. All too frequently the dimmer equipment is located against the ceiling out of reach of the serviceman or even above the ceiling in unfinished attic space. It is

A DIMMER BANK ASSEMBLY arranged for mounting in the motor generator room is shown below with operating handles proiecting through the proieciion booth wall in accordance with Code regulations.
1948-49 Theatre Catalog, 7th Edition, Page 346