Toshiba DeviceNet nv Series, Инструкция по эксплуатации, Страница: 48 / 159

Chapter 3 Install and Wiring
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(4) Single power supply central connection
In this part, a network power supply is placed at the center of a trunk line (using thick cables) with a total length
of 240 m. The current consumption of each node is shown in Figure 3-7 below. By placing the network power
supply centrally, it is possible to supply maximum current in each direction of the network.
Figure 3-8 Single power supply central connection example
a) Section 1 total current consumption = 0.1A + 0.25A + 0.2A = 0.55A
a') Section 2 total current consumption = 0.15A + 0.25A + 0.15A = 0.55A
b) Section 1 total extension = Section 2 total extension = 120 m
c) From Figure 3-5, the maximum current that can flow in the cable = about 2.56 A (calculated by linear
approximation between 100 to 150m)
d) Total current consumption < maximum current, power can be supplied to all nodes with a single power
supply central connection.
e) Use a network power supply with a rated current of 1.1 A or more.
(Select a product with sufficient margin in consideration of usage conditions, etc.)
If the current consumption of the section exceeds the maximum current of the cable with single power supply
center connection, take the following measures.
Figure 3-9 shows an example of a single power supply center connection that is overloaded.
Sections that exceed cable maximum current Interaction
One of the two sections Move one node from an overloaded section to one
Position the power strip closer to the overload section.
Both sections Use two power tap.
Node
1
Node
2
Node
3
Node
4
Node
5
V+
V-
0.1A 0.25A 0.2A 0.15A 0.25A 0.15A
Node
6
Network
power supply
Power
Tap
Section 1
120m
Section 2
120m