12
GOSSEN-METRAWATT
4.5
General Measuring Procedures
Line voltage must lie within the allowable range of 207 to 253 V for all of the following mea-
surements. This assures that the accuracy of displayed measured values corresponds with
the values specified under “Technical Data” (chapter 11, page 28).
Line voltage can be measured by setting the measuring range selector switch to the “250 V”
position (see chapter 4.3, page 10).
Measuring ranges for the measurement of protective conductor resistance, insulation resis-
tance, equivalent leakage current and contact current are protected against overload in the
event that interference voltages of up to 250 V are applied inadvertently.
Always start with the measurement of protective conductor resistance for safety class I
devices. Insulation resistance and equivalent leakage current cannot be measured if the pro-
tective conductor does not function properly. This connection must be established externally
for safety class II devices (see chapter 4.4.2).
Note!
+
Please note that overflow is indicated at the display during the measurement of pro-
tective conductor resistance and insulation resistance, if the terminals are open or if
the upper range limit is exceeded. In this case, only the character “1” is displayed at
the left-hand side of the LCD (11).
Attention!
!
Measuring current is reduced after approximately 10 minutes in the event of a
long-term short-circuit during insulation testing. Excessive temperature is indicated
at the display in this case (see chapter 11 “Display – Excessive Temp.”). If this display
appears, nominal current of 1 mA as required by DIN VDE 0413 and DIN VDE 0701
is no longer assured. After the short-circuit has been eliminated, and after a brief
cool-down period, the message is cleared from the display and subsequent
measurements once again fulfill VDE requirements.
Evaluating Measured Values
In order to make absolutely sure that limit values for insulation resistance are not fallen short
of, instrument measuring error must be taken into consideration. Minimum required display
values for insulation resistance can be taken from the following table.These values take max-
imum instrument error into consideration (under nominal conditions of use). The indicated
values correspond to the required limit values (DIN VDE 0413, part 1). Intermediate values
can be interpolated.
4.6
Residual Current Monitoring (for METRATESTER
â
5/5-F only)
For your safety, residual current at the DUT connected to the mains outlet is continuously
monitored by METRATESTER
â
5/5-F instruments. If residual current reaches a value of
greater than 3.5 mA, danger is indicated by means of a continuous acoustic signal.
Automatic shutdown does not occur (see chapter 3.1, page 8).
Limit Value M
W
Minimum Display Value, METRATESTER
â
4
Minimum Display Value,
METRATESTER
â
5/5-F
0.25
0.280
2 M
W
range
0.33
0.3
0.335
0.38
0.5
0.555
0.60
1.0
1.105
1.15
2.0
2.25
20 M
W
range
2.25
7.0
7.75
7.75
10.0
11.05
11.05