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National Instruments Corporation
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Getting Started with the NI EVS-1464RT
Do not operate the hardware in an explosive atmosphere or where there may be flammable gases or
fumes unless the hardware is UL (U.S.) or Ex (EU) Certified and marked for hazardous locations.
The hardware must be in a suitably rated IP 54 minimum enclosure for hazardous locations. Refer to
the hardware’s user documentation for more information.
You must insulate signal connections for the maximum voltage for which the hardware is rated. Do not
exceed the maximum ratings for the hardware. Do not install wiring while the hardware 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 hardware. Remove power
from signal lines before connecting them to or disconnecting them from the hardware.
Operate the hardware 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. Typical level for sealed components or coated PCBs.
•
Pollution Degree 2 means that only nonconductive pollution occurs in most cases. Occasionally,
however, a temporary conductivity caused by condensation must be expected. Typical level for
most products.
•
Pollution Degree 3 means that conductive pollution occurs, or dry, nonconductive pollution occurs
that becomes conductive due to condensation.
Operate the hardware at or below the measurement category
1
marked on the hardware label.
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 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
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voltage. This category is for measurements of
voltages from specially protected secondary circuits. Such voltage measurements include signal
levels, special hardware, 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
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). This category refers to local-level 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 in the fixed installation, and
stationary motors with permanent connections to fixed installations.
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.
