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If you need to clean the product, use a soft, nonmetallic brush. The product must be
completely dry and free from contaminants before you return it to service.
Operate the product 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 initiate signal connections for the maximum voltage for which the product is rated.
Do no exceed the maximum ratings for the product. Do not install wiring while the product is
live with electrical signals. Do not remove or add connector blocks when power is connected
to the system. Avoid contact between your body and the connector block signal when hot
swapping modules. Remove power from signal lines before connecting them to or
disconnecting them from the product.
Operate the product at or below the measurement category
Measurement circuits are subjected to working voltages
from the circuit to which they are connected during measurement or test. Measurement
categories establish standard impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of measurement categories:
•
Measurement Category I is for measurements performed on circuits not directly
connected to the electrical distribution system referred to as MAINS voltage. This
category is for measurements of voltages from specially protected secondary circuits.
Such voltage measurements include signal levels, special hardware, and limited-energy
parts of hardware, circuits powered by regulated low-voltage sources, and electronics.
•
Measurement Category II is for measurements performed on circuits directly connected
to the electrical distribution system (MAINS
electrical distribution, such as that provided by a standard wall outlet (for example, 115
AC voltage for U.S. or 230 AC voltage for Europe). Examples of Measurement Category
II are measurements performed on household appliances, portable tools, and similar
hardware.
•
Measurement Category III is for measurements performed in the building installation at
the distribution level. This category refers to measurements on hard-wired hardware such
as hardware in fixed installations, distribution boards, and circuit breakers. Other
examples are wiring, including cables, bus bars, junction boxes, switches, socket outlets
1
Measurement categories, also referred to as overvoltage or installation categories, are defined in
electrical safety standard IEC 61010-1 and IEC 60664-1.
2
Working voltage is the highest rms value of an AC or DC voltage that can occur across any
particular insulation.
3
MAINS is defined as a hazardous live electrical supply system that powers hardware. Suitably
rated measuring circuits may be connected to the MAINS for measuring purposes.
4 | ni.com | PXIe-6674 User Manual
1
marked on the hardware label.
2
and transient stresses (overvoltage)
3
). This category refers to local-level
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