User manual

8 GMC-I Messtechnik GmbH
4.2 Insulation Resistance Measurement (VDE 0413, part 2 / EN 61557, part 2)
Attention!
!
Insulation resistance measurements may only be performed
on voltage-free system components and devices!
Adhere to the prescribed sequence:
Ð Set the rotary switch (3) to the desired test voltage:
100 V, 250 V or 500 V.
Ð Contact the device under test with the test probes
(1: positive pole and 8: negative pole).
Ð When the toggle switch is in the neutral position, the
METRISO 5024 functions as a voltmeter for testing for the absence
of voltage.
Immediately after contacting the device under test, the user can
determine whether or not it is voltage-free.
A capacitively charged device under test is discharged directly
via the voltmeter’s internal resistance. Discharging can be
observed at the display. However, if the voltage value remains
constant insulation resistance cannot be measured until the
device under test has been disconnected from all sources of
voltage.
If zero voltage is displayed, measurement can be performed
immediately.
Ð Insulation resistance measurement is performed for as
long as the toggle switch is held in the MΩ position.
Read the measured value from the logarithmic scale
within a range of 100 kΩ to 400 MΩ.
Ð End the measurement by releasing the toggle switch. Capacitive
devices under test which have been charged by direct test
voltage are discharged by the voltmeter.
Ð Remove the test probes from the device under test.
Attention!
!
When insulation resistance is measured at capacitive devices under
test, e.g. cables, they may be charged with an open-circuit voltage
of up to approximately 700 V, and may retain this charge for a
lengthy period of time. This is a life endangering voltage, and the
device under test must be discharged after measurement for this
reason (see “testing for the absence of voltage” above).
Evaluating Measured Values
According to DIN VDE 0100, the insulation resistance of system
components must have a value of at least 1000 Ω per V nominal
voltage without any current-consuming apparatus in the line section
between two overcurrent protection devices or switches, or
downstream from the last overcurrent protection device, for example
Insulation Resistance Scale LED Beeper
Measured value ≥ limit value is displayed green continuous signal
Meas. value < 250 k Ω with U
N
=250 V
Meas. value < 500 k
Ω with U
N
=500 V
value is displayed green periodic sequence
of signals
Measurement not possible:
– < 100 kΩ
– Battery voltage too low
– Rotary or toggle switch
not adjusted correctly
pointer oscillates
pointer oscillates
pointer oscillates
green blinks
red
green blinks
periodic sequence
of signals
no signal
no signal
Ω
500 V
250 V
100 V
Ω
MΩ
V