©
National Instruments Corporation
3
NI PCIe-8255R User Manual
If the device is rated for use with hazardous voltages (>30 V
rms
, 42.4 V
pk
,
or 60 V
dc
), it may require a safety earth-ground connection wire. Refer to
the device specifications for maximum voltage ratings.
Because of the danger of introducing additional hazards, do
not
install
unauthorized parts or modify the device. Use the device only with the
chassis, modules, accessories, and cables specified in the installation
instructions. All covers and filler panels
must
be installed while operating
the device.
Do
not
operate the device in an explosive atmosphere or where flammable
gases or fumes may be present. Operate the device only at or below the
pollution degree stated in the specifications. Pollution consists of any
foreign matter—solid, liquid, or gas—that may reduce dielectric strength
or surface resistivity. The following is a description of pollution degrees.
•
Pollution Degree 1—No pollution or only dry, nonconductive
pollution occurs. The pollution has no effect.
•
Pollution Degree 2—Normally only nonconductive pollution occurs.
Occasionally, nonconductive pollution becomes conductive because of
condensation.
•
Pollution Degree 3—Conductive pollution or dry, nonconductive
pollution occurs. Nonconductive pollution becomes conductive
because of condensation.
Clean the device and accessories by brushing off light dust with a soft,
nonmetallic brush. Remove other contaminants with a stiff, nonmetallic
brush. The unit
must
be completely dry and free from contaminants before
returning it to service.
You
must
insulate signal connections for the maximum voltage for which
the device is rated. Do
not
exceed the maximum ratings for the device.
Remove power from signal lines before connection to or disconnection
from the device.
Caution
National Instruments measurement products may be classified as either
Measurement Category I or II. Operate products at or below the Measurement Category
level specified in the hardware specifications.
Measurement Category
1
: Measurement circuits are subjected to working
voltages
2
and transient stresses (overvoltage) from the circuit to which they
are connected during measurement or test. Measurement Category
establishes standardized impulse withstand voltage levels that commonly
1
Measurement Categories as defined in electrical safety standard IEC 61010-1.
2
Working voltage is the highest rms value of an AC or DC voltage that can occur across any particular insulation.
