Difference between Triac Leading-edge dimmer & Trailing-edge dimmer

2019-09-17 19:04:49

 Difference between Triac Leading-edge dimmer & Trailing-edge dimmer

Dimmers allow you to achieve the exact light level that you desire in a room and consequently alter the mood. There are various types of dimming options available, but the most popular are ‘phase control’ (or phase-cut) dimmers. Phase control dimmers work by chopping out parts of the voltage and reducing power to the light source. The two types of phase control dimmer available are ‘trailing-edge’ and ‘leading-edge’ and they work in different ways which ultimately affects their compatibility with certain light forms:

Leading-edge: inductive loads (e.g. magnetic low voltage transformers), resistive loads (e.g. incandescent).
Trailing-edge: capacitive loads (e.g. electronic low voltage transformers, LED drivers), resistive loads (e.g. incandescent).
However, as well as the above, there are also other differences between the two types of dimmers...

Leading-edge dimmers (TRIAC dimmers)
Leading-edge dimmer switches are cheaper and simpler than trailing-edge, and were used originally to dim incandescent and halogen bulbs or wirewound magnetic transformers. They use a ‘TRIAC’ (Triode for Alternating Current) switch to control power, and are sometimes called TRIAC dimmers.

Many existing leading-edge dimmer switches have a relatively high minimum load, which often rules out their use with modest LED or CFL lighting circuits. However, leading-edge dimmers are by far the most common dimming control in existence.

One example of an excellent leading-edge dimmer switch is the BG Screwless 1-Gang 2-Way 400W Dimmer

Trailing-edge Dimmers (Reverse phase dimmers)
Trailing-edge dimmers are more sophisticated than leading-edge dimmers. They provide 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.