GMC-I Messtechnik GmbH 33
11 Measuring the Impedance of Insulating Floors
and Walls (standing surface insulation
impedance Z
ST
)
Measuring Method
The instrument measures the impedance between a weighted
metal plate and earth. Line voltage available at the measuring
location is used as a source of alternating voltage. The equivalent
circuit of Z
ST
is regarded as a shunt connection.
Select the Measuring Function
Switching Back and Forth Between Standing Surface Insulation
Impedance and Meter Start-Up
The submenu for switching back and
forth between standing surface insula-
tion impedance and meter start-up
testing can be accessed by pressing
the softkeys shown at the left.
Connection and Test Set-
Up
Note: Use the measuring set-up described in section 12.2
(triangular probe) or the one outlined below:
Ð Cover the floor or the wall at unfavorable locations, e.g. at
joints or abutments, with a damp cloth measuring
approximately 270 x 270 mm.
Ð Place the 1081 Probe on top of the damp cloth and load the
probe with a weight of 750 N (75 kg, i.e. one person) for
floors, or 250 N (25 kg) for walls, e.g. press against the wall
with a hand isolated by a glove).
Ð Establish a conductive connection to the 1081 Probe, and
connect it to the probe connector socket at the instrument.
Ð Connect the instrument to a mains outlet with the test plug.
Do not touch the metal plate or the damp cloth with bare
hands. No more then 50% line voltage may be applied to
these parts! Current with a value of up to 3.5 mA may
flow!
Apart from this, the measured value would be distorted.
Resistance values must be measured at several points in order to
provide for adequate evaluation. Measured resistance may not be
less than 50 k at any given point. If the measured value is
greater than 30 M, Z
ST
> 30.0M always appears at the
display panel.
Evaluation of Measured Values
See Table 5 on page 58.
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