AUDAC APM Bedienungsanleitung Seite 20

Power supply calculation
The power for the APM devices will be delivered from the receiver end (from the Digital Matrix
System or from the ARU Digital Relay Unit) over the CAT6 cabling to the APM device. If the total
cable length is over 133 meters, the voltage on the APM side will become insufficient. In this
case, an ARJ03P junction box with external power supply should be applied to deliver the desired
voltage to the APM. The maximum current which can be transferred over a CAT6 cable is 0.6
Ampere. Depending of the devices connected to the bus, the ARJ03P junction boxes should be
placed in a way, the current transferred over the CAT6 cable never comes above 0.6 Amps.
The tables on page 22 shows the maximum current ratings for the devices which can be
connected to the APM bus, and shows you the maximum cable length related to the quantity of
deviced connectes to the bus.
A simplified calculation method can be used to calculate the maximum cable length, related to
the quantity of deviced connected to on the bus: L = 133 / x, where x stands for the number of
connected devices.
For example: When 6 deviced are connected to one power supply, the maximum cable length of
the databus is L = 133 / 6 = 22 meters.
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