© National Instruments Corporation 5 NI 6509 User Guide and Specifications
If you need to clean the DIO device, use a soft, nonmetallic brush. Make
sure that the DIO device is completely dry and free from contaminants
before returning it to service.
Operate the DIO 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 DIO device is rated. Do not exceed the maximum ratings for the DIO
device. Do not install wiring while the DIO device is live with electrical
signals. Do not remove or add connector blocks when power is connected
to the system. Avoid contact between your body and the connector block
signal when hot swapping modules. Remove power from signal lines
before connecting them to or disconnecting them from the DIO device.
Operate the DIO device at or below the measurement category1 marked
on the hardware label. Measurement circuits are subjected to working
voltages2 and transient stresses (overvoltage) from the circuit to which they
are connected during measurement or test. Installation categories establish
standard impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of installation
categories:
• Measurement Category I is for measurements performed on circuits
not directly connected to the electrical distribution system referred to
as MAINS3 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.
1 Measurement categories, also referred to as installation categories, are 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 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.