Electric Dimmers

Dimmer is type of lighting control that is used for varying the brightness of a light. This device works by increasing or decreasing the RMS voltage for varying the intensity of light output. The devices are available in a range of sizes, right from small units used for domestic lighting to high power units used in large theatre or architectural lighting installations.

While small dimmers are directly controlled, remote control systems are also available. The large professional dimmers are generally controlled by a digital control system.

In the earlier years, dimmers were directly controlled by means of a manual manipulation of large dimmer panels. This implied that all power had to come through the lighting control location that could be potentially dangerous.

Types of Dimmers
Dimmers are available in two types:

• Manual: These dimmers are used manually for adjusting light.
• Automatic: These dimmers are controlled automatically with the help of a programmable device such as timers and photo sensors.

The earlier dimmers were often based on rheostats. These devices were inefficient and when set to the middle brightness levels, they could dissipate a significant portion of the power rating of the load.

Variacs or variable auto transformers were introduced at a later date. These were highly efficient devices and the dimming effect was independent of the load applied, enabling easier designing of lighting that would be attached to each autotransformer channel. Variacs are not used much in residence, but are still used in other applications such as under/over voltage testing of equipment.

Applications
Dimmers are used in numerous applications including:

• Theatre
• Restaurants
• Museums
• Residence
• Offices
• Stores