DALI manual - Tridonic

.cMaintenance and troubleshootingMeasuring the voltage drop in a DALI circuitProceed as follows:Check that all the DALI devices are functioning properly.Make sure there is no communication on the DALI line.Measure the voltage at the DALI power supply.» The value must be between 11.5 V and 22.5 V; a typical value is 16 V.» A much lower value may indicate a short-circuit.Measure the voltage at the DALI device furthest from the DALI power supply.» The value must be between 9.5 V and 20.5 V.» A much lower value indicates that there is a short-circuit somewhere.Create a short-circuit between DA and DA at the DALI device furthest from the DALI power supply.Measure the voltage at the DALI power supply.» The value that you measure is the DALI voltage drop.» This value must not be higher than 2 V.» If it is higher than 2 V, check whether any of the following have occurred:» The DALI line is too long (more than 300 m at 1.5 mm2)» The cross-section is too small» High contact resistance» The value must be brought down below 2 V.Remove the short-circuit between DA and DA on the DALI device furthest from the DALI power supply.Possible solution: DALI RepeaterIf the voltage drop is greater than 2 V, a possible solution is to use a DALI RepeaterA DALI Repeater is not the right answer in every situation; its use depends to a large extent on the wiring. First, thewiring of the DALI circuit must be checked. This solution should only be used if no other solution is practical. Above all,you must find out why the system has not been working properly up to now. Make sure that you will not be faced withthe same problem again.A DALI Repeater can helpIf the DALI cable is longer than 300 m with a cross-section of 1.5 mm2.If the cross-section is too small.½ CAUTIONPlease read the data sheet carefully before using a DALI repeater.Example: DALI circuit with a voltage drop greater than 2 VIn this example the DALI voltage drop is well above the limit of 2 V. The DALI line is too long.It is 470 m instead of the permitted 300 m.DALI Manual | 08-2013 | en83 / 93