Manual

Gossen Metrawatt GmbH 83
19.2 Measuring the Impedance of Insulating Floors and Walls
(standing surface insulation impedance) – Z
ST
Function
Measuring Method
The instrument measures the impedance between a weighted
metal plate and earth. Line voltage available at the measuring site
is used as an alternating voltage source. The Z
ST
equivalent cir-
cuit is considered a parallel circuit.
Connection and Test Setup
Note
Use the measuring setup described in section 16.2 (trian-
gular probe) or the one outlined below:
➭ Cover the floor or the wall at unfavorable locations, e.g. at
joints or abutments, with a damp cloth measuring approx.
270 × 270 mm.
➭ 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 one hand which is insulated with a glove).
➭ Establish a conductive connection to the 1081 Probe, and
connect it to the probe connector socket at the instrument.
➭ Connect the instrument to a mains outlet with the test plug.
Attention!
!
Do not touch the metal plate or the damp cloth with your
bare hands.
No more than 50% line voltage may be applied to these
parts! Current with a value of up to 3.5 mA may flow!
The measured value would be distorted as well.
Start Measurement
Evaluate Measured Value
The measured value has to be evaluated after measurement has
been completed:
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 dis-
play panel.
In the event that “NOT OK” is selected, an error is indicated by the
UL/RL LED which lights up red.
See also Table 5 on page 101 with regard to evaluating measured
values.
The measured value cannot be saved to memory and included in
the test report until it has been evaluated.
Save measured value
OK
NOT OK