Loss of one phase?

What would happen in the following scenario:-

(1) One DIN relay and one DIN dimmer connected on one phase.
(2) One DIN relay and one dimmer connected on another phase.
(3) Each dimmer has a power supply.

If one phase was lost, one dimmer and one relay would not work.
Half the power supply to the system is also lost.

With one relay and one dimmer still connected to an active phase you would expect half the lights to still operate BUT with all the switches still drawing current from the one remaining power supply would the whole system collapse?

Has anyone experienced this situation?

 

It depends to some extent on the reserve capacity of the C-Bus power supplies. In general, when there are insufficient power supplies, all C-Bus communication will fail, but the microcontrollers in each unit will continue to operate as normal.

Of course, dimmers or relays which have lost mains will not be able to drive any outputs, nor will they indicate channel state on their LEDs (LED power is derived from the mains connection, not from the C-Bus connection). When the phase is restored, the units which lost mains will initialise in the normal manner, taking either the last state of the output or a predefined state, as set-up at installation time.

The units which had mains on at all times will simply be able to communicate once again, but their output states will not have changed. You should be able to control outputs on these units manually by using the buttons on the dimmers or relays themselves.

If you are concerned with maintaining communication through an event such as this, you would have to ensure that there are sufficient power supplies on two remaining phases to keep the network operating. This level of power supply redundancy can only be achieved if you can also keep within physical limits of the system, such as the current capacity of the C-Bus cable, etc.

Don