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When used to control reactive (inductive or capacitive) loads, care must be taken to ensure that the TRIAC turns off correctly at the end of each half-cycle of the AC in the main circuit. TRIACs can be sensitive to fast voltage changes (dv/dt) between MT1 and MT2, so a phase shift between current and voltage caused by reactive loads can lead to ...
A non-dim circuit is a special electrical network. In theater, it is a type of outlet usually controlled from the stage manager 's panel or from the Lighting control console . The word non-dim is used to distinguish this type of circuit which operates only in on or off modes, from a dimmer , which can be at any intensity on a continuum.
A simple SCR circuit with a resistive load. A simple SCR circuit can be illustrated using an AC voltage source connected to a SCR with a resistive load. Without an applied current pulse to the gate of the SCR, the SCR is left in its forward blocking state. This makes the start of conduction of the SCR controllable.
A Voltage controller thyristor based dimmer rack An electrical schematic for a typical SCR-based light dimmer. A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency ...
The most common application is in dimmer switches for domestic lighting control. For industrial applications previously, extremely expensive and heavy multi-tapped transformers were used as the supplies for such elements, with the corresponding winding tap being connected to the element to produce the desired temperature. This limited the ...
This circuit is called a leading-edge dimmer or forward phase dimming. Waveform of the output voltage of a thyristor dimmer set for 60 volts RMS output, with 120 V input. The red trace shows the output device switching on about 5.5 ms after the input (blue) voltage crosses zero.
Adjusting the brightness of light emitted by a light source is then merely a matter of setting at what voltage (or phase) in the AC half-cycle the dimmer begins to provide electric current to the light source (e.g. by using an electronic switch such as a triac). In this case the PWM duty cycle is the ratio of the conduction time to the duration ...
0-10V dimmer In production lighting this system was replaced by analog multiplexed systems such as D54 and AMX192 , which themselves have been almost completely replaced by DMX512 . For dimmable fluorescent lamps (where it operates instead at 1–10 V, where 1 V is minimum and 0 V is off), the system is being replaced by DSI , which itself is ...