Phase-cut dimmers: Foward Phase & Reverse Phase Dimmer

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Phase-cut dimmers: Foward Phase & Reverse Phase Dimmer

2019-07-31

There are various types of dimming control, but the most popular is phase control dimmers. The dimmers work by chopping out parts of the voltage and reducing power to the light source to dim luminous flux even from 1% to 100% (this value depends on dimmer and driver). The phase control(phase-cut) dimmer available are ‘trailing-edge’ and ‘leading-edge,’ and they work in different ways which ultimately affects their compatibility with the lights.

The leading-edge dimming cut off in the wave on its ascending side, from the beginning (phase cut-off at ignition). The leading-edge dimmer is used traditionally for inductive loads (e.g., magnetic low voltage 12V transformers, Constant current dimmable LED drivers), resistive loads (e.g., incandescent, mains voltage halogen lamps & capsules).

The trailing-edge dimming cut-off in the wave on its descending side, from the end cutting backward (phase cut-off at switch off). So this way of dimming causes less interferences than leading-edge dimming. The trailing-edge dimmer is suitable for capacitive loads (e.g., electronic low voltage 12V transformers, LED drivers), resistive loads (e.g., incandescent, mains voltage halogen lamps & capsules).

However, there are also other differences between the two types of dimmers. Leading-edge dimmers (TRIAC dimmer switch) are cheaper and simpler than trailing-edge and were used initially to dim incandescent and halogen bulbs or wire-wound magnetic transformer. ‘TRIAC’ (Triode for Alternating Current) switch is used to control power.

The leading-edge dimmer switches have a relatively higher minimum load, which often restrict their use with efficient LED or CFL lights.

Trailing-edge Dimmers (Reverse phase dimmers)
Trailing-edge dimmers are more sophisticated than leading-edge dimmers. The trailing-edge dimmer provides a much smoother dimming control, absent of any buzzing noise, and is ideal for use in most premises.
A trailing-edge dimmer has a lower minimum load than leading-edge dimmers, making it a better choice for dimming modestly sized low-powered lighting circuits.

The universal dimmer supports both types of dimming(leading and trailing edge), and others that support only one variety.

Leading-edge

Trailing-edge

Universal(Leading-edge and trailing-edge)

LED dimmer