Megger ATEC 210415 Series, Manual

Page: 49 / 82

M
42
AVTM21-415Ja Rev. A June 2005
Guide for Testing Insulation Resistance of Rotating Machinery , IEEE
Standard 43.
Guide for Insulation Maintenance for Large Alternating Current Rotating
Machinery . IEEE Standard 46.
Guide for Making Dielectric Measurements in the Field . IEEE Standard 62.
Guide for Insulation Testing of Large AC Rotating Machinery with High Direct
Voltage . IEEE Standard 95.
APPLYING THE TEST SET
The Test Set measures the test voltage and the resistance of the
item under test; the operator must introduce the time
parameter into the test.
For safety reasons one terminal of the Test Set must be
connected to ground. One side of the apparatus being tested
must be connected to ground. This minimizes exposure of
high voltage leads and conforms to the way most apparatus is
constructed. This leaves one terminal at high voltage and for
dc test sets this high voltage lead is preferably negative with
respect to ground.
The Test Set measures the test voltage and the resistance of the
item connected across the two output terminals, that is, the
high voltage terminal and ground.
For most purposes the two-terminal resistance measurement is
all that is required since all paths between High Voltage (Line)
and Ground (Earth) are simultaneously measured and a total
resistance value is found.
There are certain important practical situations where a two-
terminal measurement does not convey the desired
information.