Basic Electricity • Three elements to an electrical circuit • 1. A source of electricity • 2. A load using the electricity • 3. A circuit: provides a path between the two • Two types of electricty • direct current or DC and alternating current or AC • US standard is 3 phase 60 cycle AC
Three related electrical attributes • 1. Amp: unit of measurement for electron flow from one point to another • 2. Watt: a unit of measurement expressing the amount of electrical energy consumed by a device or load • 3. Volt: a unit of measurement expressing electrical pressure to form a current.
Electrical Analogy • Amperage is the amount of water available to pass through the hose to the pump • Wattage is the amount of water that must be pulled through the hose to the pump • Voltage is the pressure at which the water is pushed through the hose.
Electricity in Theatrical Terms • Electricity is supplied to a lighting instrument • The source of the electricity is the dimmer • A cable bridges the gap between the dimmer and the instrument.
Dimmers • Piano Boards • Dimmer Racks
Circuitry • Wires conduct the electricity • Insulators cover each wire to contain and separate electrical flow • Plugs installed on both end of the wires make certain that the electricity in the wires is connect properly • They are constructed to be male or female. • Twist Lock plugs are what we use in our theater • Lighting instruments have male plugs • Dimmers have female plugs.
Load Calculations • The Power Formula • W=V*A • A=W/V • V=W/A • If two of the factors are known the rest can be figured out. • Most theatrical cabling is 12-Gauge • #12 carries 20 amps, #14 carries 14
Example 1 • Is it possible to plug three 100 watt instruments simultaneously into a single #12 cable?
Answer • Which variation do you use? W/V=A • W=3000 watts • V=110 volts • 3000/110=27.27 • The answer is NO
Example 2 • The dimmer is rathed to handle 30amps. How many 750 Watt instruments can be plugged into that dimmer?
Answer • W/V=A • 750/110=6.8 • 30/6.8=4.4 instruments • W=V*A • 30*110=3300 • 3300/750=4.4 instruments
Computer Control (light boards) • DMX 512 is the recognized standard of communication between the dimmer and the control board. • The lighting console “plays back” different memories by loading them into a fader. • Time duration is the length of time that occurs when memory is loaded in to a fader.
Lighting consoles • Submasters: control assigned channels • Remote Focus Units
Console Logic • 2 Scene Manual Preset Boards • Computer controlled systems
Computer consoles • Cue: a command at a specific moment to initiate a specific action. • Called Cue:results in an action being taken • Light Cue: a change in dimmer or channel intensities from one “state” or “look” to another.
Types of Cues • Preset cue: lighting state on stage before the show • Fronts up cue: adds only front light • Usually taken just before the show starts • Fronts out cue: subtracts front light • Usually taken just before the end of an act or performance
Types of Cues • Base cue: the first cue of a scene on which all other subsequent cues are built on • Fade to Black Cue: fades everything to black • Blackout: fast change to black • Bow Cue: curtain call look. • Post set cue: lighting seen while audience is leaving