![markx phase dimming markx phase dimming](http://i.stack.imgur.com/DpcyT.gif)
The more time spent by the transistor in the analog mode, the more heat it produces. Using a transistor as a switch (on or off) produces minimal heat, while using a transistor to directly control the voltage to a load creates a lot of heat. In both cases, FPC or RPC, the dimmers are producing triplen harmonics. Neon, ballasted loads, fans, and small electric motors will generate destructive inductive kickback energy when dimmed by an RPC dimmers either should not be used with these loads or should switch to forwardphase control (FPC) to dim such loads. They work well for filament loads or electronic lowvoltage transformers but are unusable with inductive loads. Reverse Phase Drawbacks l l RPC dimmers can be very quiet and compact. By gradually turning off the current rather than turning it on, a reverse phase angle dimmer reduces the filament noise in a similar fashion as a forward phase SCR dimmer without the need of a choke. A transistor differs from an SCR in that it can be controlled to gradually vary the current, not just to switch it on. l The commercially-practical implementation of reverse phase dimming uses IGBT transistors. IGBTs are commonly available with ratings up to 1200 amps and about 1700 V, making them suitable for use in just about any dimming application imaginable. They are significantly more efficient and easier to control than most other power semiconductors. Invented in the late 1970 s by Frank Wheatley at RCA and currently in its fourth or fifth generation of development, IGBTs are the preferred component for power control applications. IGBT stands for Insulated Gate Bipolar Transistor. The IGBT is a semiconductor that is fast replacing both regular transistors and the trusted SCR in many power control applications. In some cases, the load will perform badly in other cases, the load and the dimmer may sustain permanent damage. l With its distorted waveform, SCR dimming is simply unsuitable for many loads, including most electronic transformers and electronic ballasts for fluorescent and metal-halide sources. The harmonics also produce audible noise and overheating in the distribution wiring and feeder transformers and can lead to penalties from utility companies. In the worst possible case, the neutral current can be up to 73% higher than any one-phase current. ” This means that the phase currents in a three -phase system do not cancel out as intended, but, rather, add up.
![markx phase dimming markx phase dimming](https://i.ebayimg.com/images/g/ZxoAAOSwA6helt5g/s-l300.jpg)
MARKX PHASE DIMMING FULL
But when operated at anything less than full output, the SCR dimmer presents a distinctly non-linear load, creating what is known as “triplen harmonics.
![markx phase dimming markx phase dimming](https://www.kaoyi.com/uploads/images/Phase-CutDimming_Index_0909.jpg)
l SCR dimmers are actually quite efficient, and very little gets lost in the dimming circuit itself. lįorward Phase Drawbacks The disadvantages of the technique include noisy filaments that can buzz audibly, and the possibility of cross-interference between dimmers and audio systems. l Patented techniques for producing a pure sine wave output with variable amplitude to control lighting levels use transistors to slice the mains into pulses, vary the current using pulse width modulation, and average the result, which produces a continuous, variable amplitude smooth sine wave. The convergence of improvements in transistor technology, lower technology costs and more improved processors brought forth reverse phase dimming, also called trailing edge dimming, which switched OFF the current flow at a predetermined interval. The familiar SCR and Triac devices were used to control the intensity of light, varying the switch ON point of the lamp current each half cycle (forward phase). l When forward phase technology emerged, electronic components made it possible to allow only portions of the AC cycle through to the load. Forward phase dimming with SCR technology has reigned over conventional loads since the early 1960 s and is still today the most cost-effective choice for dimming installations.
MARKX PHASE DIMMING PROFESSIONAL
Technology Comparison Professional dimming has come a long way from the candle snuffers of the 18 th century to the gas tables of the 19 th century and resistance dimmers of the early 20 th century.