International projectionist (Jan-Dec 1947)

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FORM 1A: GENERATOR-ARC CIRCUIT DATA Remarks Theatre Date . . City Revised State Theatre Circuit Chief Projectionist 1. MOTOR-GENERATOR SETS Make & Model Number of sets Serial Nos If more than one set, how many are used for each arc at one time? If more than one set, how many arcs supplied by each set? If two or more sets are used to supply same arc at same time, how interconnected? 4. FIELD RHEOSTATS Make & model Number of rheostats per generator . Capacity, amperes Resistance range Number of settings Normal setting Where located Remarks Remarks 5. A.C. POWER CONTROL 2. MOTORS H.P Volts Cycles Phase Speed If separate from generators, make, model, and serial Nos Main switch: Type Where located Fuses: Type Rating Where located Circuit breakers: Type . . Rating Where located Control cabinet & starter: Control box Starter Relay switch Remarks Remarks 6. BALLAST RESISTANCES Make & model •. Number of resistances Where more than one is used as a unit, number per circuit, specifications, and how connected 3. GENERATORS Full output voltage Output voltage used Capacity, kilowatts Speed Resistance of one unit Number & type of brushes Ballast voltage-drop . Capacity, amperes . . , Remarks If separate from motors, make, model and serial Nos 8. TRANSMISSION LINE Length of "run" How many power wires from generator room to booth B & S gauge of wire Type of cable Line resistance per circuit Line voltage-drop per circuit Main switch: Type Where located Fuses: Type Rating Where located Circuit breakers : Type Rating Where located Remarks 9. METERS Line (A.C.) voltmeters: Make & model Number of voltmeicrs . . . Capacity, volts Normal reading How connected Where located Generator or arc voltmeters : Make & model . Number of voltmeters . . . Capacity, volts Normal reading How connected Where located Ammeters : Make & model Number of amme'ers . . . . Capacity, amps Normal reading How connected Where located Remarks 10. EMERGENCY EQUIPMENT Remarks 7. ARC POWER Arc voltage (drop) Arc resistance Arc current the sum from the voltage at the generator Formula: ea = E — [eb + ex] METHOD 3. Rule: To find the arc-drop multiply the current in amperes by the resistance of the arc in ohms. Formula: Ra is the ohmic resistance of the arc: ea -■= IRa To determine the ohmic resistance of the arc: METHOD 1. (The line voltage-drop needed with this method will be considered under Section 8.) Rule: To find the arc resistance add the ballast-drop to the line-drop. Subtract the sum from the generator voltage. Divide the difference by the current in amperes. E — [eb + ej Formula: Rn I METHOD 2. Rule: To find the arc resistance divide the arc-drop in volts by the current in amperes. ea Formula: Ra = — I To determine the current at the arc: this value is the same as the current anywhere in the arc circuit. Practically every installation is equipped with one or more 20 INTERNATIONAL PROJECTIONIST • April 1947