NI WSN-9791 User Guide and Specifications
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levels, special equipment, limited-energy parts of equipment, circuits powered by regulated
low-voltage sources, and electronics.
•
Installation 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 Installation Category II are measurements performed on household appliances, portable tools,
and similar products.
•
Installation 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 in the fixed installation,
and stationary motors with permanent connections to fixed installations.
•
Installation Category IV is for measurements performed at the primary electrical supply
installation (<1,000 V). Examples include electricity meters and measurements on primary
overcurrent protection devices and on ripple control units.
Safety Guidelines for Hazardous Locations
The NI WSN-9791 is suitable for use in Class I, Division 2, Groups A, B, C, D, T4 hazardous locations;
Class I, Zone 2, AEx nC IIC T4 and Ex nL IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI WSN-9791 in a potentially explosive
environment. Not following these guidelines may result in serious injury or death.
Caution
Do
not
disconnect the power supply wires and connectors from the gateway unless power
has been switched off.
Caution
Do
not
install or remove the gateway unless power has been switched off.
Caution
Substitution of components may impair suitability for Class I, Division 2.
Caution
For Zone 2 applications, install the WSN system in an enclosure rated to at least IP 54 as
defined by IEC 60529 and EN 60529.
Special Conditions for Hazardous Locations Use in Europe
The NI WSN-9791 has been evaluated as Ex nA nL IIC T4 equipment under DEMKO Certificate No. 07
ATEX 0626664X. Each gateway is marked II 3G and is suitable for use in Zone 2 hazardous locations,
in ambient temperatures of –40 °C
≤
Ta
≤
70 °C.
