GOSSEN-METRAWATT
19
6.3
Measuring Insulation Resistance
This measurement may only be performed if the device under test has successfully completed protec-
tive conductor resistance testing
.
This measurement may not be performed if all-pole electrically
actuated switches are included in the device under test.
➭
Connect the device under test as described in chapter 4.4, page 11.
Make sure that the jack (10) is connected to exposed conductive parts at the DUT for safety
class II and III devices.
➭
Set the measuring range selector switch (5) to the “2 M
W
” range (METRATESTER
â
4
only), or the “20 M
W
” range.
➭
Switch all DUT functions on and make sure, for example, that all contacts for tempera-
ture sensitive switches and the like are closed.
➭
Read the measured value in “M
W
” from the LCD (11).
Insulation resistance may not fall short of the following values:
The following limit values for insulation resistance may not be fallen short of:
1)
Equivalent leakage current measurement must be performed if the applicable limit value is fallen short of.
Attention!
!
If a value of 0.5 M
W
is fallen short of for safety class I devices with heating elements,
equivalent leakage current measurement must be performed and passed in accor-
dance with chapter 6.4, page 20.
Each exposed conductive part must be contacted with the test probe connected to
the jack (10), and insulation resistance must be measured for safety class II and III
devices, and battery powered devices.
No insulation resistance measurement is required for safety class III devices, or for
battery powered devices which fulfill both of the following conditions:
– Nominal power
£
20 VA
– Nominal voltage
£
42 V.
Batteries must be disconnected during the performance of measurements at battery
powered devices.
Device Type
Limit Value
Minimum Display Value
Safety class I devices
0.5 M
W
(2 M
W
range)
0.555 M
W
(2 M
W
range), 0.60 M
W
(20 M
W
range)
Safety class I devices
with heating elements
0.5 M
W
1)
0.555 M
W
(2 M
W
range), 0.60 M
W
(20 M
W
range)
Safety class II devices
2.0 M
W
(20 M
W
range)
2.25 M
W
Safety class III devices
or battery powered devices
1000
W
/V or 250 k
W