Operate the device 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 device is rated.
Do not exceed the maximum ratings for the device. Do not install wiring while the device is
live with electrical signals.
Operate the device at or below the Measurement Category I
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 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
3
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.
•
Measurement Category II is for measurements performed on circuits directly connected
to the electrical distribution system. This category refers to local-level electrical
distribution, such as that provided by a standard wall outlet (for example, 115 V for U.S.
or 230 V for Europe). Examples of Measurement Category II are measurements
performed on household appliances, portable tools, and similar E Series devices.
•
Measurement Category III is for measurements performed in the building installation at
the distribution level. This category refers to measurements on hard-wired equipment
such as equipment in fixed installations, distribution boards, and circuit breakers. Other
examples are wiring, including cables, bus-bars, junction boxes, switches, socket-outlets
1
Measurement Category is defined in electrical safety standard IEC 61010-1. Measurement
Category is also referred to as Installation Category.
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 equipment. Suitably
rated measuring circuits may be connected to the MAINS for measuring purposes.
NI USB-6501 User Guide
|
© National Instruments
|
3
