National Instruments PXI-1428 User Manual
Page 16
Chapter 2
Installation
2-4
ni.com
Clean the device and accessories by brushing off light dust with a soft,
nonmetallic brush. Remove other contaminants with a stiff, nonmetallic
brush. The unit must be completely dry and free from contaminants before
returning it to service.
You must insulate signal connections for the maximum voltage for which
the device is rated. Do not exceed the maximum ratings for the device.
Remove power from signal lines before connection to or disconnection
from the device.
Caution
National Instruments measurement products may be classified as either
Installation Category I or II. Operate products at or below the Installation Category level
specified in the hardware specifications.
Installation 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. Installation Category establishes
standardized impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of Installation
(Measurement
3
) Categories:
•
Installation 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.
•
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.
1
Installation 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
Installation Category is also referred to as Measurement 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.