DALI manual - Tridonic

.cDesigning a DALI applicationMaximum of 16 DALI scenes per DALI circuitThe current on the DALI circuit must not exceed the maximum current of the power supply (DALI PS/PS1 =200mA or DALI PS2 = 240mA).The maximum cable length depends on the maximum permitted voltage drop along the DALI cable; this isdefined as 2 V max. This corresponds to a maximum cable length of 300 m for a line cross-section of 1.5 mm²;contact resistance must also be taken into account. A voltage drop of 2V must not be exceeded.The recommended minimum cable cross-section is 1.5 mm²Current draw of the DALI circuitEach device in the DALI circuit consumes current via the DALI circuit. The total current draw on the DALI circuit mustnot exceed the maximum current of the DALI power supply.To determine the current draw of a DALI circuit both the current draw of the DALI devices and the current draw of theDALI controllers must be taken into consideration. The current draw of a DALI device is defined in the DALI standardas 2 mA. The current draw of the individual DALI controllers (ComfortDIM devices) is shown in the relevant datasheets.It is important that the current draw of the DALI circuit does not exceed the maximum current of the power supply. Inthe case of DALI-PS and DALI-PS1 this is 200 mA.Example: DALI circuit with 24 dimmable ballasts (PCA EXCEL), 3 DALI-GC and 3 DALI-SCCurrent draw of the individual DALI components (from the data sheet):Dimmable ballasts (PCA EXCEL) = 2 mAGroup controllers (DALI-GC) = 6 mAScene controllers (DALI-SC) = 6 mATotal current = Σ Current draw of DALI devices + Σ Current draw of DALI controllersTotal current = 24 x ballasts + 3 x DALI GC + 3 x DALI SCTotal current = 24 x 2 mA + 3 x 6 mA + 3 x 6 mA = 84 mAMaximum cable lengthThe maximum cable length depends on the maximum permitted voltage drop along the DALI cable; this is defined as 2V max. Typically, this requirement is safely met for a cable length of 300 m and a cable cross-section of 1.5 mm².Additional voltage drops at terminal points must be taken into consideration. For cross-sections smaller than 1.5 mm²the maximum cable length is reduced accordingly....DALI Manual | 08-2013 | en59 / 93