User manual

GMC-I Messtechnik GmbH 5
4 Measuring Direct and Alternating Voltage
Direct voltages and sinusoidal alternating voltages with frequencies
ranging from 40 to 200 Hz can be measured with this instrument. Needle
deflection is always positive for direct voltage measurements regardless of
polarity at the terminal connections. Alternating voltage is displayed as an
RMS value.
➭ Set the function selector switch to the “1000 V” position.
➭ Make certain that the needle points to the “0” mark at the V scale in
the idle state. Readjust the needle if necessary with the adjusting
screw for mechanical zero adjustment.
➭ Rotary switch position is irrelevant for voltage measurement.
➭ Probe the measuring point with both test probes.
➭ Read the measurement value from the V scale.
Notes
• Allowable overload capacity for the voltage measuring range is
1200 V.
• Input impedance for the voltage measuring range is 0.9 MΩ.
• Devices under test with capacitive charges are automatically
discharged by the test instrument. The corresponding drop in voltage
can be observed at the display.
5 Measuring Insulation Resistance
Before performing measurement, make certain that the device under test
is voltage-free (see chapter 4).
5.1 Measurement Procedure
➭ First set the function selector switch to the R1 position.
➭ Briefly short circuit the test probes and press the measurement key to
check for full-scale deflection for R1 = 0 MΩ (zero adjustment).
The needle must point to the above indicated full-scale deflection
mark in the idle state. Readjust the needle if necessary with the rotary
knob for electrical zero adjustment.
➭ Depending upon the nominal voltage of the device under test, select a
test voltage of either 50 V, 100 V, 250 V, 500 V or 1000 V with the
rotary switch.
Note
Full-scale deflection must be tested in the following cases, and must be
readjusted if required in order to attain a measuring accuracy of 1.5%:
• Each time a different nominal voltage is selected
• For resistance measurements of long duration
➭ Probe the measuring point with both test probes.
➭ Press the measurement key and read the measurement value from
the appropriate scale.
➭ If needle deflection is insufficient, switch to the next highest
measuring range, i.e. R2 or R3, with the function selector switch.
➭ Multiply the displayed value by the conversion factor which appears
opposite the selected nominal voltage:
Attention!
!
Do not touch the conductive ends of the two test probes after the
instrument has been activated for the measurement of insulation
resistance.
If measurement is being performed at a purely ohmic device
under test, current may flow over your body, which, although it
does not reach life endangering levels, causes a clearly
discernible shock.
When measurements are made at capacitive devices under test,
e.g. cables, the DUT may be charged with voltages of up to
approximately 1200 V, depending upon selected nominal voltage.
Contact with the device under test after measurement is, in this
case, life endangering!
For this reason, the DUT must be discharged in a controlled
fashion as described in chapter 4 on page 5.
Nominal Voltage: 50 V 100 V 250 V 500 V 1000 V
Conversion
Factor:
x 0.1 x 0.2 x 0.5 x 1 x 2