AMC1100 Datasheet, PDF (15/22 Pages) Texas Instruments – Fully-Differential Isolation Amplifier for Energy Metering

AMC1100
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ISOLATION GLOSSARY
SBAS562 – APRIL 2012
Creepage Distance: The shortest path between two conductive input-to-output leads measured along the
surface of the insulation. The shortest distance path is found around the end of the package body.
Clearance: The shortest distance between two conductive input-to-output leads measured through air (line of
sight).
Input-to-Output Barrier Capacitance: The total capacitance between all input terminals connected together,
and all output terminals connected together.
Input-to-Output Barrier Resistance: The total resistance between all input terminals connected together, and
all output terminals connected together.
Primary Circuit: An internal circuit directly connected to an external supply mains or other equivalent source that
supplies the primary circuit electric power.
Secondary Circuit: A circuit with no direct connection to primary power that derives its power from a separate
isolated source.
Comparative Tracking Index (CTI): CTI is an index used for electrical insulating materials. It is defined as the
numerical value of the voltage that causes failure by tracking during standard testing. Tracking is the process that
produces a partially conducting path of localized deterioration on or through the surface of an insulating material
as a result of the action of electric discharges on or close to an insulation surface. The higher CTI value of the
insulating material, the smaller the minimum creepage distance.
Generally, insulation breakdown occurs either through the material, over its surface, or both. Surface failure may
arise from flashover or from the progressive insulation surface degradation by small localized sparks. Such
sparks result from a surface film of a conducting contaminant breaking on the insulation. The resulting break in
the leakage current produces an overvoltage at the site of the discontinuity, and an electric spark is generated.
These sparks often cause carbonization on insulation material and lead to a carbon track between points of
different potential. This process is known as tracking.
Insulation:
Operational insulation—Insulation needed for correct equipment operation.
Basic insulation—Insulation to provide basic protection against electric shock.
Supplementary insulation—Independent insulation applied in addition to basic insulation in order to ensure
protection against electric shock in the event of a failure of the basic insulation.
Double insulation—Insulation comprising both basic and supplementary insulation.
Reinforced insulation—A single insulation system that provides a degree of protection against electric shock
equivalent to double insulation.
Copyright © 2012, Texas Instruments Incorporated
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