Dimming Guide
Lighting is a major use of energy in all hotels. When dimming is used in combination with Elecon’s other energy saving technologies owners and operators can benefit from major cost savings.

Light dimming is also an essential part of modern lighting control to set the scene and mood of a room and to provide an outstanding guest experience.

There are various types of dimming control devices available, but the most popular are ‘phase control’ (or phase-cut) dimmers, these can be of the “Leading Edge” or “Trailing Edge” phase control type as described here. Dimming is done by controlling 220VAC loads or 12-24VDC loads for LED’s.

After extensive research and development Elecon has developed special dimming modules to cater for both mains 220VAC and low voltage LED lighting loads.

Trailing Edge Dimmers
Trailing edge dimmers are more sophisticated than leading edge dimmers, and usually have a ‘MOSFET’ or ‘IGBT’ switch rather than a ‘TRIAC’ and coil and are sometimes called ‘electronic’ dimmers. This benefits the user with smoother, silent dimming control and no “buzzing” noise.

A trailing edge dimmer also has a lower minimum load (often 10W) compared with leading edge dimmers, making it a better choice for dimming low-powered LED lighting circuits.

Trailing edge dimmers can also benefit older incandescent and halogen bulbs with the ‘soft start’ (low in-rush current) feature built into the dimmer control circuit which prevents “filament” bulbs from dying or exploding of thermal shock when first switched on.

PWM Dimming
PWM dimming can be categorised as a type of Digital dimming. Instead of adjusting the DC current, PWM dimming achieves the same effect by varying the duty cycle of the constant current. It switches the input current of the LED lamp at a high frequency between 0A and the rated current, and this modification of on-off rate of the LED will result in the change of light output level (percentage).

This is suitable for LED’s that need to maintain colour consistency when dimmed down to lower than 40%, and lighting applications with mixed colour control. The power supply should be of high quality and be able to run the LED at a high enough frequency.

0(1)-10V Analogue Control for Dimming
This module and method often works very well for dimming dedicated LED fittings when coupled to a 0(1)-10V dimmable driver unit. Dimming is often smoother and lower than mains dimming options. This method requires separate ‘control’ cables between the dimmer module and the light fitting driver.

Compatibility Issues
Older incandescent “filament” bulbs are all dimmable by default, however LED retrofit bulbs have a built-in driver in their base. The driver converts AC power to DC power and maintains a constant current to the LED. This is at odds with a phase control dimming system, since the driver attempts to compensate for the sliced out portions of input voltage.

LED fixtures such as down lights usually include an external driver, either of a ‘constant current’ or ‘constant voltage’ type, depending on the LED array design. In either case, the same issue arises: the LED driver or power supply will try to patch up the missing parts of input voltage.

Because of this widespread LED compatibility problems exist, these problems show up in a number of ways, including flickering, flashing, dead travel, ghosting, dropout, pop-on, and pop-corning. So all LED lamps should be fully tested with the dimmer module and driver units to ensure matching and a smooth reliable installation.