LDX 86 High Frame Rate/HD/3G/4K Camera Platform User’s Guide (v2.0)
11
Triax cable systems
Do not allow system earth currents to exceed 1.5 A in the outer shield of the Triax cable or 0.2
A in other cable shields.
To avoid excessive earth currents in a Triax system, galvanically separate the power earth
connection of equipment connected to the camera from the camera earth.
It is strictly prohibited to short circuit the inner and outer shields of a Triax cable used to
connect a camera to an XCU.
Galvanic separation
Because of the nature of Triax systems, with long distances between camera and its XCU, the
risk of earth currents flowing is greater. These earth currents can result in damage to the
equipment.
For example, a monitor connected directly to the monitor output of the camera is powered
locally. The earthing point of the monitor’s power supply can be at a different potential with
respect to the earthing point of the XCU. If the power earth of the monitor is also the video
earth, then this earth potential is transferred to the camera via the shield of the BNC connector.
The difference in earth potential between the camera and the XCU results in an earth current in
the Triax system.
To prevent earth currents from flowing in the Triax system, we recommend galvanic separation
of earthed equipment connected to the camera. This separation can be achieved by using an
isolation transformer between the local power outlet and the equipment connected to the
camera. Alternatively, use equipment that has a double insulation and therefore does not
require an earth connection.
