DIAGNOSTIC STATUS CODES
IT TRANSISTOR CONTROL
Page
15
4.2.2.d High Power Signals (Level HP)
4.2.2.a Low-Level Signals (Level L)
Low-level signals are designated as
level L
. These
consist of:
Power wiring is designated as
level HP
. This consists
of DC buses and motor wiring with currents greater
than 10 A.
•
Analog signals 0 through ±15 V
The following are specific examples of level HP
signals used in drive equipment cabling:
•
Digital signals whose logic levels are less than 15
V DC
•
Motor armature loops
•
4 – 20 mA current loops
•
DC outputs 10 A and above
•
DC busses less than 15 V and 250 mA
•
Motor field loops 10 A and above
The following are specific examples of level L signals
used in drive equipment cabling:
4.2.3 Cable Spacing Guidelines
•
Control common tie
Recommended spacing (or clearance) between
cables (or wires) is dependent on the level of the
wiring inside them. For correct level separation when
installing cable, the customer must apply the
general
guidelines
(section 4.2.3.a), outlined below.
•
DC buses feeding sensitive analog or digital
hardware
•
All wiring connected to components associated
with sensitive analog hardware with less than 5V
signals (for example, potentiometers and
tachometers)
4.2.3.a General Cable Spacing
•
Digital tachometers and resolvers
•
Dash display cabling
The following general practices should be used for
all
levels
of cabling:
•
RS-232 cabling
Note:
Signal inputs to analog and digital blocks
should be run as shielded twisted-pair (for example,
inputs from tachometers, potentiometers, and dash
displays).
•
All cables and wires of like signal levels and
power levels must be grouped together.
•
In general, different levels must run in separate
wire bundles, as defined in the different classes,
identified above. Intermixing cannot be allowed,
unless noted by exception.
4.2.2.b High-Level Signals (Level H)
•
Interconnecting wire runs should carry a level
designation.
High-level signals are designated as
level H
. These
signals consist of:
•
If wires are the same level and same type signal,
group those wires from one location to any other
location together in multiconductor cables or bind
them together with twine or zip-ties.
•
Analog and digital signals greater than 15 V DC
and less than 250 mA
•
When unlike signals must cross, cross them in
90° angles at a maximum spacing. Where it is
not possible to maintain spacing, place a
grounded steel barrier between unlike levels at
the crossover point.
For example, switch inputs connected to battery
volts are examples of level H signals used in drive
equipment cabling.
4.2.2.c Medium-Power Signals (Level MP)
4.2.4 Cabling for Vehicle Retrofits
Medium power signals are designated as
level MP
.
These signals consist of:
Reducing electrical noise on vehicle retrofits requires
careful planning. Lower and higher levels should
never encircle each other or run parallel for long
distances.
•
DC switching signals greater than 15 V
•
Signals with currents greater than 250 mA and
less than 10A
It is practical to use existing wire runs or trays as long
as the level spacing (see section 4.2.2) can be
maintained for the full length of the run.
Existing cables are generally of high voltage potential
and noise producing. Therefore, route levels L and H
in a path separate from existing cables, whenever
possible. For level L wiring, use barriers in existing
wire runs to minimize noise potential.
The following are specific examples of level MP
signals used in drive equipment cabling:
•
DC busses less than 10 A
•
Contactor coils less than 10 A
•
Machine fields less than 10 A
November 2005
