Dimming Types Explained

There are a variety of dimming systems and technologies in the market  and it can be confusing to know your way around the right solution for your project. This article aims to assist in understanding dimmer technology better to help you make more informed choice. 

Residential and household dimming

Phase-cut dimming (otherwise known as Triac dimming)

This is the most common dimmer type that is used in homes throughout New Zealand. It works by the connection of a dimmer module (often rotary or push button) in series within the lighting circuit. The dimmer works by 'cutting' the sine wave that resides on the lighting circuit, which is then interpreted by the attached electronic driver (transformer) which adjusts the dimming proportionately to the amount of sine wave that is cut. There are two phase dimming types; 'leading-edge' and 'trailing-edge' with the latter being generally better suited to LED lighting electronic driver technologies. The benefit of phase dimming is that it does not require additional wiring to work. The downside is that the dimming capability and usability is highly variable and depending on the load and products attached to it, phase dimming can lead to poor performance in some instances. Often phase dimmers have maximum loads that are relatively small - this makes this technology largely unsuitable for use in commercial applications. 

Commercial and Industrial dimming 

0-10V Dimming 

0-10V dimming is a lighting control method that – on direct current voltage (DC) between 0 and 10 volts – can produce light at varying intensity levels. 0-10V dimming is the simplest control system for lighting. Put simply, the voltage that is present in the dedicated 2-core cable that is required for this dimming system to work dictates the dimming level of the LED drivers that are attached to the signal. In most instances, each volt is commensurate with a linearised percentage of dimming i.e 1 volt is 10% light, 2 volts is 20% light and so on. The benefit of this system is that it is very simplistic and relatively inexpensive to integrate. The downside is that a separate cable is required - which increases wiring costs and the technology has limits to its functionality. 

DALI Dimming 

Digital Addressable Lighting Interface (DALI) is a trademark for network-based products that control lighting.A DALI network consists of at least one application controller and bus power supply (which may be built into any of the products) as well as input devices (e.g. sensors and push-buttons), control gear (e.g., electrical ballasts, LED drivers and dimmers) with DALI interfaces. Application controllers can control, configure or query each device by means of a bi-directional data exchange. DALI systems allow for sophisticated network setups that allow a high degree of customisation - and are generally very reliable. The downside is that the systems are very expensive to setup, require a 2-core cable to be run to the lighting circuits, as well as the purchase of a bus. In many cases, a programmer is also required to setup the network. 

PWM Dimming 

Pulse-width modulation (PWM) is a method of reducing the average power delivered by an electrical signal, by effectively chopping it up into discrete parts. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the load. Like 0-10V dimming, a 2-core cable is required to be wired to each of the LED drivers that the system communicates with. It is rare that this dimming technology is used in New Zealand buildings due to the ease of use of 0-10V which has similar advantages but is less complex to set up and understand.