©
National Instruments Corporation
3
Getting Started with the NI PCI-1426
Measurement Category
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 Category establishes standardized impulse withstand voltage levels that commonly occur
in electrical distribution systems. The following is a description of Measurement (Installation
3
)
Categories:
•
Measurement Category I is for measurements performed on circuits
not
directly connected to the
electrical distribution system referred to as MAINS
4
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.
Unpacking
The NI 1426 ships in an antistatic package to prevent electrostatic discharge from damaging device
components. To avoid such damage in handling your device, take the following precautions:
1.
Ground yourself using a grounding strap or by touching a grounded object, such as the computer
chassis.
2.
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.
3.
Remove the device from the package and inspect it for loose components or any other signs of
damage. Notify National Instruments if the device appears damaged in any way. Do
not
install
a damaged device in the computer.
Store the NI 1426 in the antistatic package when not in use.
1
Measurement Categories as defined in electrical safety standard IEC 61010-1.
2
Working voltage is the highest rms value of an AC or DC voltage that can occur across any particular insulation.
3
Measurement Category is also referred to as Installation Category.
4
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.