National Instruments NI PXI-7831R User Manual page 20

Chapter 1 Introduction
1
Installation categories, also referred to as measurement categories, are 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.
NI PXI-7831R User Manual
Do not substitute parts or modify the NI PXI-7831R except as described in
this document. Use the NI PXI-7831R only with the chassis, modules,
accessories, and cables specified in the installation instructions. You must
have all covers and filler panels installed during operation of the
NI PXI-7831R.
Do not operate the NI PXI-7831R in an explosive atmosphere or where
there may be flammable gases or fumes. If you must operate the
NI PXI-7831R in such an environment, it must be in a suitably rated
enclosure.
If you need to clean the NI PXI-7831R, use a soft, nonmetallic brush. Make
sure that the NI PXI-7831R is completely dry and free from contaminants
before returning it to service.
Operate the NI PXI-7831R only at or below Pollution Degree 2. Pollution
is foreign matter in a solid, liquid, or gaseous state that can reduce dielectric
strength or surface resistivity. The following is a description of pollution
degrees:
• Pollution Degree 1 means no pollution or only dry, nonconductive
pollution occurs. The pollution has no influence.
• Pollution Degree 2 means that only nonconductive pollution occurs in
most cases. Occasionally, however, a temporary conductivity caused
by condensation must be expected.
• Pollution Degree 3 means that conductive pollution occurs, or dry,
nonconductive pollution occurs that becomes conductive due to
condensation.
You must insulate signal connections for the maximum voltage for which
the NI PXI-7831R is rated. Do not exceed the maximum ratings for the
NI PXI-7831R. Do not install wiring while the NI PXI-7831R is live with
electrical signals. Do not remove or add connector blocks when power is
connected to the system. Remove power from signal lines before
connecting them to or disconnecting them from the NI PXI-7831R.
Operate the NI PXI-7831R at or below the installation category
on the hardware label. Measurement circuits are subjected to working
2
voltages and transient stresses (overvoltage) from the circuit to which they
are connected during measurement or test. Installation categories establish
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