AMC1200

SBAS542A

– APRIL 2011 – REVISED AUGUST 2011

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Pollution Degree:

Pollution Degree 1

—No pollution, or only dry, nonconductive pollution occurs. The pollution has no influence on

device performance.

Pollution Degree 2

—Normally, only nonconductive pollution occurs. However, a temporary conductivity caused

by condensation is to be expected.

Pollution Degree 3

—Conductive pollution, or dry nonconductive pollution that becomes conductive because of

condensation, occurs. Condensation is to be expected.

Pollution Degree 4

—Continuous conductivity occurs as a result of conductive dust, rain, or other wet conditions.

Installation Category:

Overvoltage Category

—This section is directed at insulation coordination by identifying the transient overvoltages

that may occur, and by assigning four different levels as indicated in IEC 60664.

1. Signal Level: Special equipment or parts of equipment.

2. Local Level: Portable equipment, etc.

3. Distribution Level: Fixed installation.

4. Primary Supply Level: Overhead lines, cable systems.

Each category should be subject to smaller transients than the previous category.

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© 2011, Texas Instruments Incorporated