NI PCIe-8255R User Manual 4 ni.com
occur in electrical distribution systems. The following is a description of
Measurement (Installation1) Categories:
• Measurement Category I is for measurements performed on circuits
not directly connected to the electrical distribution system referred to
as MAINS2 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 (e.g., 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 products.
• 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 in the fixed installation, and stationary motors with
permanent connections to fixed installations.
• Measurement 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.
UnpackingThe NI 8255R ships in an antistatic package to prevent electrostatic
discharge from damaging device components. To avoid such damage in
handling the device, take the following precautions:
• Ground yourself via a grounding strap or by holding a grounded object,
such as the computer chassis.
• Touch the antistatic package to a metal part of the computer chassis
before removing the device from the package.
Caution Never touch the exposed pins of connectors.
1 Measurement Category is also referred to as Installation Category.
2 MAINS is defined as the (hazardous live) electrical supply system to which equipment is designed to be connected for the
purpose of powering the equipment. Suitably rated measuring circuits may be connected to the MAINS for measuring
purposes.