Powering a Coax or HFC System

When testing the voltage of a series of batteries, they should be within ___ vDC of each other.

0.3

Standby power supplies use___ vDC batteries providing 3 hrs of backup.

12

If you had shorter coaxial runs between the power supply and active devices, what voltage would you use?

60 vAC

What is the output voltage for a power supply?

60/90 vAC

The placement of power insertion depends on the design of the distribution system and type of power supply used. What are the typical voltages used to power an HFC plant?

60/90 volts

If you had longer coaxial runs between the power supply and active devices, what voltage would you use?

90 vAC

This device passively combines RF signals with up to 90 vAC from a line power supply.

LPI

Is centralized powering the ideal setup for rural areas?

No; ideal for dense areas, like downtown

Which two powering architectures are commonly used in coaxial cable networks? (choose 2)

centralized, distributed

line power supplies (LPS)

come in two forms. can be aerial on underground. big gray box on poles, big green box underground. can be standby or nonstandby.

standby power supply

contain batteries that provide power to the system in the event of commercial power failure. typical battery life goes for 3 hours. require more regular maintenance and periodic replacement of batteries. should be measured to confirm they are within 0.3 vDC of each other. generally 12 volt lead acid batteries.

Identify the most common type of powering using multiple power supplies to energize line power inserters (LPI), designed to feed power in both directions, upstream and downstream, from an insertion point in the HFC.

distributed

A standby power supply can run for 8 hours battery power.

false; 3 hours

Be careful handling the power supply unit. The ferroresonant transformer which provides regulated power output generates a significant amount of ___.

heat

What device is used to insert power onto the coaxial cable for powering amplifiers and nodes?

line power inserter

What's inside the power inserter prevent RF signals from passing to the AC input and line power supply while allowing the AC power to pass?

low-pass filter

distributed powering

multiple LPS that are located throughout the network; placed at locations convenient to tie into the commercial grid. output is fed in both up and down stream directions for the LPS. not ideal for densely populated areas.

line power inserter (LPI)

power from the LPS insertion point. has 3 ports; 1 input for LPS and 2 are splicted into a coax span.

nonstandby line power supplies

requires no batteries, completely dependent on the utility company power grid. less expensive and require less maintenance. can be used with backup generators, which maintain service if commercial power fails. not often used in HFC networks.

centralized powering

single LPS is used to provide power for a large portion of the network. typically large pedestal mounted units. generally the entire area served by an optical node. separate coax runs are provided from the central LPS to each LPI. appropriate for densely populated areas w short runs of coax.

___ power supplies contain batteries for supplying power output when utility power is interrupted.

standby

Often a power outage on the commercial power grid will affect only a portion of the overall power system. However, an interruption of power in a small part of a coaxial or HFC plant can disrupt signals further downstream or upstream where the commercial power service is unaffected.

true