Twinax Cabling Noise - IBM 5500 Operational, Installation, And Maintenance Manual

Twinax Cabling Noise

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Chapter 6: Twinax Client Cabling Requirements and Problem Solving
Minimum distance of 15 feet if a twinax cable is installed near equipment or
power lines using 440 volts or more (especially if the equipment is carrying
hundreds of KVA).
Minimum distance between twinax cables and fluorescent, neon, or
incandescent lighting fixtures is 5 inches.
The minimum distance between twinax cabling and equipment or power lines
using less than 440 volts is as follows, depending on the power consumption:
Figure 36: Twinax Cable Distances
Cable Description
Twinax and unshielded
power lines
Twinax in grounded
metal conduit and
unshielded power lines
(or in ungrounded
metal conduit and
shielded power lines)
Twinaxial and power
lines both in separate
grounded metal conduit
If twinax cables are connected to the 5500 Control Unit, but are not connected
at the device end, or if the shield is open in a cable, this open cable or shield
can conduct noise into the system and cause 5500 Control Unit system
problems. Make sure that all attached twinax cables are properly terminated
and disconnect all unused twinax cables at the 5500 Control Unit's twinax
brick.
AC Noise
AC Noise on twinax systems is either steady state noise or intermittent
transient noise.
When checking for AC noise, consider the possibility that the line is more
sensitive because of the number of cable connections or a cable length
approaching the maximum of 5000 feet (1524 meters). These distances are
shorter when running in Express mode or cabling is an unshielded twisted
pair.
Steady State AC Noise
This type of noise is measured between a known good ground (system ground
can be used if this has been checked for proper grounding) and twinax shield
with an AC voltmeter or an oscilloscope, after the twinax cabling is
disconnected from the system or controller. A voltage present indicates a
Planning, Installation, and Maintenance Guide
2 KVA or less 2-5 KVA
5 inches 12 inches
2.5 inches 6 inches
1.2 inches 3 inches
over 5 KVA
24 inches
12 inches
6 inches