User manual

12 GMC-I Messtechnik GmbH
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 7, page 23).
Line voltage can be measured by setting the measuring function selector switch to the “U
Netz
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 7 “Display – Excessive Temp.”). If this display ap-
pears, nominal current of 1 mA as required by DIN VDE 0413 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 maximum ser-
vice error into consideration (under nominal
conditions of use). The indicated values corre-
spond to the required limit values
(DIN VDE 0413, part 1). Intermediate values can
be interpolated.
4.6 Residual Current Monitoring
For your safety, residual current at the DUT connected to the mains outlet is continuously
monitored by METRATESTER 5 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 MΩ Minimum Display Value
0,25 0,33
0,3 0,38
0,5 0,60
1,0 1,15
2,0 2,25
7,0 7,75
10,0 11,05