Download Power Supply Boundary - Bentley Communities

HFC Powering
Introduction
CATV networks utilize its coaxial cable to carry the electrical power used by
amplifiers, optical nodes, NID and any other active devices installed on the
network. The electrical powering is provided by a Power Supply connected to
the power line that transforms ordinary 110 Volts to a stable 60V or 90V 60Hz
power source.
Power supplies are installed in a pole mount or ground mount enclosure. In
certain cases, enclosures will house more than one power supply to feed
portions of the network with distinctive power sources.
Batteries can be installed inside the same enclosure as the power supply or in
a separate enclosure placed directly on top or under it. These batteries will
provide power to the network for a limited amount of time, enough for a field
technician to be able to install a UPS on the power supply.
Monitoring devices can also be installed on power supply to remotely monitor
and control every power source installed on the network.
Power insertion
The RF and AC are combined on the coaxial cable by using RLC circuitry (Resistor, inductors and
capacitors) as illustrate bellow. The capacitor will acts as a short in high
frequency (RF) and as an open circuit in low frequency (AC) while the
inductor does the inverse.
This circuit isolates the RF signal from the AC source and at the same time
isolates the AC source from the RF signal source. You will find similar
circuitry inside Power Inserters to isolate the power supply from RF signal,
in Tap to allow the circulation of AC from the Input to the Output or from
the output to the input of the tap while preventing the AC to circulate on
the drops, and on active devices such as amplifier or NID to separate AC
and RF signal on distinctive path.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 1 of 10
Active devices
In a coaxial network, you will find different kind of equipment powered from the network itself. Each of
them will draw a certain amount of current from the power supply and will only work within a
predefined voltage level. The following is a list of active devices usually found on a CATV network:

Optical node

Coax amplifier

Network Interface Device (NID)

Addressable Taps

Field Switching Module
(CLEARPath)
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 2 of 10
HFC network powering
On a Hybrid Fiber-Coax network, small portions of the network are fed directly by optical signal carried
on a fiber and converted to electric signal via an optical node. These nodes usually provide signal to 500
house counts and depending on the population density, can cover a small area in city zone or a larger
area in rural zone.
Different powering scenario will need to supported the different HFC architecture on dense and rural
area. Scenario A and B will usually be found in low to medium density area while scenario C and D will
mostly be found in dense area.
A. Single power supply feeding a single node
B. Multiple power supplies feeding a single node
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 3 of 10
C. Power supply feeding multiple nodes
D. Power supply feeding portions of nodes
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 4 of 10
Single node powering examples
1. Single power supply connected to the network through a power inerter.
2. Single power supply connected to the network through one of the optical node leg.
3. Single power supply connected to the network through one of the amplifier leg.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 5 of 10
4. Multiple power supply feeding different portion of the network.
5. Dual power supply installed in the same cabinet feeding two section of the network.
6. Dual power supply installed in the same cabinet feeding two nodes.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 6 of 10
Cross node powering example
1. Single power supply feeding two nodes with the use of power inserter and a splitter.
2. Single power supply feeding two nodes with the use of power with multiple outputs (up to 4).
3. Single power supply feeding two nodes by connecting the power supply to one leg of one optical
node and joining the two networks with a jumper and two power inserters.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 7 of 10
The power supply could also be connected to the leg of an amplifier or to an additional power
inserter installed on the network.
4. Single power supply feeding two nodes connected together for coaxial redundancy.
The cable at the input of the second node will carry power and RF signal. Plug-in will need to be
calculated for the second node as it could become the redundant source in case of fiber outage.
5. Single power supply feeding two nodes with a jumper connecting the nodes power ports
together.
6. Connecting two output tap ports together.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 8 of 10
Devices connecting Power Supply to the network
Power supplies can be connected to the network by using the following equipments:

A Power Inserter

One of the legs of an Amplifier (Power Port)

One of the legs of an optical node (Power Port)
Fuses / Power director are used inside these equipments to direct the power to the desired portion of
network. With this method, it is possible to assign a power supply to the desired amplifiers or nodes.
Bentley Coax requirements
Power Jumper
Cable placed between a power supply and a coax devices. This cable carries only AC to the network.
Jumper data will be saved in the same coax cable table in Oracle, but a special parameter will allow the
application to stop the RF calculation when encountering it.
The Jumper cable can use any model of cable (P3-625, P1-750, etc.).
Power Port
Information specifying if an amplifier or a node has a port to which a power jumper can be connected
to. A power port could also be added to a tap (exception) or on misc devices to provide more flexibility.
Power Supply
New power supplies come with multiple outputs (4 outputs). It should be possible to connect multiple
cables to a power supply to feed multiple nodes. Power will be calculated as if the cable was split.
Enclosure housing two nodes should already be manageable with our current version. They will only
need to create a cell with an enclosure & a power supply and another cell with only the power supply to
simulate the double supplies.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 9 of 10
Power supply will need to be placed from the design menu as the other coaxial equipment.
Power Inserter
A Power Inserter can be placed anywhere on the network. A cable will join the Power Supply to the AC
Power Inserter port and depending on how it is fused, it will be able to feed the network upstream
and/or downstream.
Power inserter will need to be placed from the design menu as the other coaxial equipment.
RF redundancy
Some optical nodes will include an RF input for redundancy purpose. This coaxial cable will also carry the
power from one node to the other.
Example: GainMaker® Optoelectronic Node 1 GHz with 40/52 MHz Split and RF Redundancy
Power Block
Power block are placed on coax cable to identify where the powering will stop. It simulates the removal
of a fuse in a coaxial device. Power block are identified by the following symbol: |(
Powering with Power block
After having placed the power supply, the power jumper, the power inserter and the power blocks on
the network, the user will activate the Powering command and select the power supply to start the
power calculation. The application will start identifying all the active devices on the network by verifying
the connectivity and stopping at every cable where a power block is found. Voltage and current will then
be calculated and applied to every devices as well as the total current drawn from the Power Supply.
Power Supply Boundary
Power Supply boundaries are placed on the network to identify the area feed by a particular power
supply. This method is used to avoid having to place individual power block at every location where the
power supply stops feeding the coax network.
Powering with Power Supply Boundary
After having placed the power supply, the power jumper, the power inserter and the power boundary
on the network, the user will activate the Powering command and select the power supply boundary to
start the power calculation. The application will start by identifying the power supply inside the power
supply boundary and will start calculating powering on the network inside the boundary. Voltage and
current will then be calculated and applied to every devices as well as the total current drawn from the
Power Supply.
© 2009 Bentley Systems, Incorporated. All rights reserved.
Page 10 of 10