Eaton Electrical Cutler Hammer MN05001002E - Manual (Page 21)

Intelligent Technologies QCPort System Install Manual
November 2005
MN05001002E For more information visit www.eatonelectrical.com Page 21
Sizing a Power Supply
It is important to verify that the power supply is properly sized for the load and the length
of the QCPort system. To calculate if the placement and the size of the power supplies
are adequate, refer to the examples in the Using the Sizing Calculation on page 23.
Supplying Power
Follow these guidelines to protect your nodes and to achieve the best results when
supplying power to the QCPort cable system.
• Use power supplies rated at 24V.
• Select a power supply that provides sufficient current for all attached nodes.
• Make sure you derate the power tap and the power supply for the expected
temperature using the manufacturer’s guidelines.
• Use a power supply that has its own current limit protection.
Adjusting the Configuration
When the sections have a voltage drop less than 4.65V, your configuration will operate
properly. Ideally, the voltage drops for each section should be within 10%. If one section
has a substantially greater voltage drop than the other, you should attempt to balance the
load of the cable system by moving the power supply or nodes. Some ways to make
your system operational include the following:
• Shorten the overall length of the cable system.
• Move the power supply in the direction of the overloaded section.
• Move devices from the overloaded section to another section.
• Move higher current loads as close to the supply as possible.
• Add a second power supply to the cable system.
• Break the QCPort system into two separate networks to reduce the number of
nodes on each.