－ 14 －
－ 13 －
1. Do not apply any voltage to the measuring terminals.
2. Disconnect the power supply from the circuit to be
measured and make sure any voltage does not remain
on it, then make the measurement.
3. Do not touch the circuit to be measured while measuring
as the instrument generates high voltage for the
measurement.
4. Pay attention not to get shocked as the instrument and
the circuit to be measured are charged with high voltage.
5. Discharge the high voltage charged to the circuit to be
measured to prevent the risk of electric shock. (See the
section 5-4.)
1. High voltage is generated on the measuring terminals
It is recommended that you make the insulation resistance
measurement with any low or unknown withstanding
voltage equipments or parts (semiconductors, etc.)
disconnected from the circuit for breakage prevention.
Pay special attention to computer-related equipments.
2. Make a measurement with a test voltage that is close to
the working voltage of the circuit to be measured.
3. It may take longer time to measure insulation resistance
when the circuit to be measured has a capacitance
component.
4. Generally, connect the alligator clip to the earth side
(Ground) and the measurement probe to the circuit side
(LINE) when the circuit to be measured is grounded. (This
connection way shows generally lower value than the
other connection.)
5. The earth lead connected to the LINE side should not
touch the circuit to be measured or the earth in order to
prevent measurement error.
6. Insulation resistance changes a lot depending on
temperature and humidity. Also it changes depending
on the applied voltage (Test voltage). Generally higher
temperature, higher humidity, or higher test voltage shows
lower insulation resistance.
7. Oscillation noise during the measurement is not due to
failure.
5-3 Insulation Resistance Measurement
WARNING
CAUTION
Test voltage selection mode
The instrument makes only necessary voltages enabled
between 15 V, 25 V, 50 V, 100 V, 125 V, 250 V, and 500 V.
Only the selected test voltages can be used after the
setting. For instance, after you make 50 V, 125 V, and 250 V
enabled, only those 3 voltages can be used. (The indication
15V, 25V, 100V, and 500V will be turned off.)
To re-select test voltages you need, enable the voltages in
the test voltage selection mode again.
Press 1 sec.
or more.
Test voltage selection mode
The fig. shows 15 V rage is selected.
25 V range is selected.
25 V range will be removed.
To add the 25 V range
on the instrument,
press the test button again.
Test voltage selection completed.
To be ready to measure.
Press both buttons
and hold 1 sec. or more
when the power is off.
How to sellect a test voltage