Getting Started with the NI PCI-8252
2
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Keep away from live circuits. Do
not
remove equipment covers or shields unless you are trained to do
so. If signal wires are connected to the device, hazardous voltages can exist even when the equipment is
turned off. To avoid a shock hazard, do
not
perform procedures involving cover or shield removal unless
you are qualified to do so. Disconnect all field power prior to removing covers or shields.
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 occur
in electrical distribution systems. The following is a description of Measurement (Installation
3
)
Categories:
•
Measurement Category I is for measurements performed on circuits
not
directly connected to the
electrical distribution system referred to as MAINS
4
voltage. This category is for measurements of
voltages from specially protected secondary circuits. Such voltage measurements include signal
levels, special equipment, limited-energy parts of equipment, circuits powered by regulated
low-voltage sources, and electronics.
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.
3
Measurement Category is also referred to as Installation Category.
4
MAINS is defined as the (hazardous live) electrical supply system to which equipment is designed to be connected for the
purpose of powering the equipment. Suitably rated measuring circuits may be connected to the MAINS for measuring
purposes.
