C-Bus Power Requirements

Adequate C-Bus Power Supply Units must be installed or enabled to support the total consumption of all C-Bus devices connected to the C-Bus Network segment.

C-Bus Power Supplies are specially designed to share load when distributed around the C-Bus network. To achieve this the integrated C-Bus Power Supplies have an output impedance of approximately 32 Ω up to their maximum current of 200 mA. Once the maximum current is exceeded the output impedance increases sharply to limit the current to a safe level in the event of a fault in the C-Bus network wiring.

There must not be more than 2000 mA of total C-Bus Power Supply capacity enabled on a single C-Bus network segment as this is the limit of the current carrying capacity of the C-Bus network cable.

The relay unit includes a switchable inbuild C-Bus Power Supply, which can supply up to 200 mA to the C-Bus network when enabled. By default, the inbuilt power supply is disabled, but can be enabled (or disabled) via the front panel.

The SpaceLogic C-Bus Commission software provides information if the inbuilt power supply is enabled/disabled in each unit, as well as a summary of the total network power capacity and consumption. This can be helpful in determining the power supply requirements of a particular network.

NOTE: The relays draw 20 mA from the C-Bus network when mains power is not connected.