DALI Emergency encompasses most of the standard features of DALI in addition to features and commands specific to emergency products. These are outlined below:
To ensure maximum battery life (especially through the construction stages), a smart control system can use the REST command to extinguish the emergency lamp (when power has been lost) and limits the number of continual charge and discharge cycles present in the commissioning or installation phase. This reduces the stress on the battery and ensures the longest possible life.
The most important test for an emergency device is the duration test. This test allows the device to change to emergency mode and discharge the battery.
During the period the device checks the status of the lamps, circuit and battery to ensure that the device is working correctly. The result of the test is stored and can be returned to the control system when required.
NOTE: The emergency device stores the discharge time in minutes. This allows a control system in Australia to check that the first duration test lasted 1.33x the rated duration of the device, ensuring compliance to the Australian Standard AS2293.
A test designed to quickly check the unit’s functionality. During this short test the unit is able to check that the battery, lamp and circuitry are all working correctly. The result of this test is stored and can be returned to the control system when required
The prolong time function of the emergency DALI protocol gives installers the ability to prolong the emergency light’s Emergency state. This time can be set from 0 to 60 minutes and can ensure that a safe lighting level is present after a short power failure.
INSTALLATION HINT: It is a requirement under Australia Standard AS2293 that the emergency lighting should remain on until the traditional lighting is restored. Particular attention to advanced lighting technologies such as HID lighting needs to be made. The emergency lighting should remain on until this lighting has re-ignited. The utilization of the prolong time feature allows HID lighting to re-ignite before the emergency lighting is turned off.
Another measure that can be initiated by the control system is the INHIBIT feature which can stop the emergency DALI device from going into emergency mode. The INHIBIT will time out after 15 minutes for safety, but is reset every time the inhibit command is received.
MAINTENANCE NOTE: It is critical that LED and CCFL lighting is replaced once the lamp has reduced substantially in lumen output. Under the Australian building code it is a requirement for the lighting to be replaced when this occurs. Lamp life counters are one of the most reasonable approaches to ensuring the lamp source is replaced at the correct time.
LAMP LIFE COUNTERS
Maintenance is important for emergency devices, as neglect can lead to serious consequences, i.e. the loss of life due to evacuation failure.
Lamp life counters are an important feature of the DALI emergency standard and allow the control system to determine if the lamp needs replacing.
Two lamp status counters are present on a DALI emergency device, one counts normal lamp use whilst the other counts emergency lamp use. Lamp life counters are extremely important for new lamp sources like LED and CCFL as these lamps don’t fail; rather they reach a point where their light level has fallen under 50%.
DALI emergency devices can carry out function or duration tests automatically (even without a DALI system attached). To achieve this there are two inbuilt calendars which allow the installer to set the interval between successive duration and/or function tests.