User manual

6 GMC-I Messtechnik GmbH
5.2 Evaluation of Measurement Values
In order to assure that insulation resistance values do not fall below those
required by DIN VDE regulations, insulation tester inherent deviation must
be taken into consideration.
Required minimum display values for insulation resistance which take
maximum operational measurement deviation of the METRISO 1000A into
consideration (under nominal conditions of use) can be determined with
the following table. These are the minimum values which must be dis-
played, in order to assure that actual values do not fall below the required
limit values (DIN VDE 0413 part 1). Intermediate values can be interpo-
lated.
The table applies to a nominal voltage of 500 V. The values in the table must be
multiplied by a conversion factor for other nominal voltages.
5.3 Rapid Testing of Insulation Resistance
In addition to illuminating the measuring point, the lamp in the test probe
can also be used for rapid GO/NO-GO testing of insulation resistance. As
long as the lamp is lit, minimum values for insulation resistance are fulfilled
in accordance with DIN VDE 0100. The signal remains lit as long as
insulation resistance demonstrates the following values:
6 Measuring Low-Impedance Resistance (0 to 4 Ω)
Attention!
!
Make certain that the device under test is voltage-free before
performing measurements in the low-impedance measuring
range.
The measurement key should not be depressed if a high-
impedance device under test is probed, or if the test probes are
idle.
➭ Set the function selector switch to the “4 Ω” position.
➭ Briefly short circuit the test probes and press the measurement key to
check for full-scale deflection at “0 Ω”. The needle must point to the
“0” mark at the 4 Ω scale in the idle state. Readjust the needle if
necessary with the adjusting screw for mechanical zero adjustment.
➭ Probe the two points between which low-impedance resistance is to
be measured with the test probes.
➭ Activate the measurement key and read the measurement value from
the 4 Ω scale.
Notes:
• Resistance is measured with direct current.
If it can be expected that the measurement value will be influenced by
the polarity of the measuring current (e.g. if a diode is included in the
measuring circuit), reverse the test probes and repeat the
measurement.
• Resistance values which fluctuate at the beginning of the
measurement include, for example:
– Resistance with a high inductive component
– Incandescent lamp resistance values which change due to
warming caused by the measuring current
– Poor contact resistance at contact points
Scale R1 Scale R2 Scale R3
Limit Value
[MΩ]
Display Value
[MΩ]
Limit Value
[MΩ]
Display Value
[MΩ]
Limit Value
[MΩ]
Display Value
[MΩ]
0.1 0.13 0.2 0.25 2 2.5
0.2 0.25 0.3 0.38 3 3.8
0.3 0.38 0.4 0.5 4 5.0
0.5 0.63 5 6.3
11.251012.5
Insulation
Resistance
> 0.1 MΩ > 0.2 MΩ > 0.5 MΩ > 1 MΩ > 2 MΩ
Nominal
Voltage
50 V 100 V 250 V 500 V 1000 V