: Lights up when the measured value is equal to or greater than the criterion for
the comparator function during insulation-resistance measurement, or when the
measured value is equal to or less than the criterion during resistance measure-
ment.
: Lights up when the criterion for the comparator function is indicated.
: Lights up when "1000 V" is selected, if the 0ΩADJ key has not been pressed.
: Lights up when the LOCK key is pressed to perform continuous measure-
ment of insulation resistance or resistance.
: Indicated during insulation-resistance measurement, or begins flashing when the
input voltage exceeds AC 70 V (±10 V).
: Overflow indicator. Indicated when the measurement exceeds the maximum indica-
tion value.
Pre-measurement inspection
Ensure that the test leads are not disconnected
1. Use the function selector to select Ω function.
2. Short the test lead tips.
3. Confirm that the reading is below 1 Ω when pressing the MEASURE key.
Insulation Resistance Measurement
To select 1000 V, set the function selector to 1000 V while press-
ing the 0ΩADJ.
: Overflow indication
An abbreviation for overflow, the display OF is analogous to a ∞ indication in an
analog insulation tester. When measurements are larger than the effective
maximum indicated values of each function, the display will indicate .
[Measurement example] When the display indicates in the 1000 V function,
measurements are detected as larger than 4000 M
Ω
. When nothing is connected
to the test lead, is also displayed.
Preparing for Measurement
1. Set the function selector to 250 V, 500 V, or 1000 V. To select 1000 V, set the
function selector to 1000 V while pressing the 0ΩADJ key. When the
function switch is turned from OFF to 1000 V, hold down the 0ΩADJ key until
"MΩ" appears on the display. If the 0ΩADJ key has not been pressed and
"1000 V" is selected, appears on the display. In this case 1000 V is not
applied when the MEASURE key or LOCK key is turned on.
2. Make sure that indicator does not appear. If the indicator appears, please
replace the batteries.
3. Connect the black test lead to the measurement terminal on the earth side of
the instrument. Connect the red test lead to the measurement terminal on
the line side of instrument.
4. Connect the black test lead to the ground side of the object being measured.
Except when measuring insulated resistance between ground and the object
being measured, connect the black test lead to an optional point.
5. Connect the red test lead to the object being measured.
Measuring Only While the Key is Pressed
•Start
1. Press the MEASURE key. The high-voltage warning lamp begins flashing,
and the indicator appears on the display.
2. Read the measurement after it has stabilized.
•End
1. Release the MEASURE key to end measurement. The current
measurement is automatically held.
2. When the object to be measured must be discharged, read and follow the
instructions given under "Discharge Function" below.
Measuring without Holding the Key (Continuous Measurement)
•Start
1. Hold down the LOCK key for more than 2 seconds. The high-voltage
warning lamp begins flashing, and the indicator and appear on
the display.
The MΩ HiTESTER continues with measurement even if the LOCK key or
MEASURE key is not held down.
2. Read the measured value after it has stabilized.
• End (Shutdown method when is indicated)
1. Press the LOCK (STOP) key or MEASURE key to end measurement. The
current measurement is automatically held.
2. When the object to be measured must be discharged, read and follow the
instructions given under "Discharge Function" below.
• If the object to which the test leads are connected is live, even if the MΩ
HiTESTER is not performing measurement, the high-voltage warning lamp
and indicator will flash on the display.
• Insulation resistances are unstable by nature. The readings may not stabilize
with some objects; this does not necessarily indicate a malfunction.
• If the object has a capacitive component, the MΩ HiTESTER may indicate a
value smaller than the actual resistance immediately after the start of mea-
surement. The reading will gradually increase to indicate the actual resis-
tance.
• If the function switch is turned during measurement, the MΩ HiTESTER will
stop measurement.
• If is indicated even if the measurement is performed with the tip of the
test leads short-circuited, a conductor in the test leads may be broken.
• Make sure the high-voltage warning lamp off first, and then select the Resis-
tance Measurement functions or OFF.
• Some objects may require time until the measurements are stable. (Approx. 5 sec.)
Discharge Function
When measuring an insulation resistance that contains a capacitance element,
a charge proportional to the measurement voltage accumulates, and if undis-
charged could lead to an electric shock accident.
1. End measurement without disconnecting the test leads from the object.
2. The built-in discharge circuit automatically discharges the item.
3. During discharging, the high-voltage warning lamp and indicator flash.
They will go out when the voltage falls below approximately 30 V.
4. Discharge time varies with capacity.
AC Voltage Measurement
1. Set the function selector to V.
2. Connect the test lead to the instrument's measurement terminal.
3. Connect the test lead to the circuit being measured and read the displayed
value. Do not use the MEASURE key or LOCK key.
Resistance Measurement
Preparing for Measurement
1. Set the function selector to Ω.
2. Connect the test lead to the instrument's measurement terminal.
3. Connect the test lead to the object being measured.
Measuring Only While the Key is Pressed
•Start
1. Press the MEASURE key and read the displayed value.
•End
1. Release the MEASURE key to end measurement. The current
measurement is automatically held.
Measuring without Holding the Key (Continuous Measurement)
•Start
1. Hold down the LOCK key for more than 2 seconds. The appear
on the display.
The MΩ HiTESTER continues with measurement even if the LOCK key or
MEASURE key is not held down.
2. Read the measured value.
• End (Shutdown method when is indicated)
1. Press the LOCK (STOP) key or MEASURE key to end measurement. The
current measurement is automatically held.
0ΩAdjustment Function
To indicate the resistance of the object itself, the zero-adjust function stores the
resistances of the test leads and fuse and deducts these values from measure-
ment values.
1. Set the function selector to Ω.
2. Connect the test lead to the instrument's measurement terminal.
3. Short-circuit the metal tips of the test leads.
4. To start measurement, press the MEASURE key, or hold down the LOCK
key for more than 2 seconds.
5. Press the 0ΩADJ key. lights up, and the display indicates "0.00 Ω".
6. Connect the test lead to the object being measured.
7. Read the measured value.
• The indication can be zero-adjusted when the reading is 3 Ω or less. If the
0ΩADJ key is pressed when the reading is over 3 Ω, "Err.1" is displayed.
• If the test leads are short-circuited during resistance measurement, the mea-
surement current will exceed 200 mA, accelerating battery consumption.
Perform the zero adjustment as quickly as possible and open the circuit as
soon as the adjustment is complete.
• If is indicated even if the measurement is performed with the tip of the test
leads short-circuited, a conductor in the test leads or the fuse may be broken.
Example of measuring the earthing
conductor resistance
Measure the earthing conductor resistance at Ω range. Please refer to the low
resistance measurement for measuring method.
Comparator Function
The comparator function compares the measurement with a set criterion, indi-
cates PASS or FAIL, and sounds the buzzer during resistance or insulation-
resistance measurement.
Using Comparator
1. Set the function selector to 250 V, 500 V, or 1000 V or Ω.
2. Press the COMP key. The COMP indicator, REF indicator, criterion, and the
condition for sounding the buzzer ( or ) appear on the display.
The display changes to the criterion-setting screen. The criterion changes
each time the COMP key is pressed. Press the key repeatedly until the
criterion to be used is displayed.
Press the 0ΩADJ key. This switches the display between and ,
allowing you to select the criterion for sounding the buzzer. For example, if
you switch the display to , the buzzer sounds when the comparator
result is .
3. Press the MEASURE key or the LOCK key to start measurement. The REF
indicator and the criterion go out. The display returns to the measurement
display screen. The MΩ HiTESTER compares measurements and the
criterion.
Result Indication
Insulation-resistance measurement: When the measurement is smaller than
the criterion, is indicated. When the measurement is equal to or greater
than the criterion, is indicated.
Resistance measurement: When the measurement is greater than the crite-
rion, is indicated. When the measurement is equal to or smaller than the
criterion, is indicated.
Select a criterion from the presets shown in the table below.
For example, when the function switch is turned to "250 V," every time the
COMP key is pressed, the criterion changes as follows: 0.2 MΩ 0.4
MΩ ... 200 MΩ 0.2 MΩ ....
• When the criterion setting screen is shown (step 2 above), if the MΩ HiT-
ESTER remains idle for 2 seconds, the REF indicator, the criterion, and
or are no longer displayed, and the display reverts to the previ-
ous screen. However, the COMP indicator remains on, indicating that the
comparator function is enabled.
• If power is turned OFF after the comparator function is enabled, the function
is automatically enabled when the power is turned ON again. The last crite-
rion setting made before the power is turned OFF is also held.
When Not Using Comparator
To disable the comparator function, hold down the
COMP
key for more than 2
seconds. The
COMP
indicator goes out, and the comparator function is disabled.
Automatic Power-Saving Mode
The instrument will automatically enter power-saving mode about 10 minutes
following the last operation, and all displayed values disappear.
When the power is turned ON, the auto power save function is automatically
enabled (APS lights up).
To Switch from Power-Saving Mode
Set the function selector to OFF before returning to the original position.
Disabling the Auto Power Save Function
While holding down LIGHT key, turn the function switch to turn ON the power.
Measurement principles
1.Insulation Resistance Measurement
The insulation resistance of test object Rx is obtained by supplying a voltage V
to the test object and measuring the current leaking from the test object and the
voltage supplied using the formula (Voltage supplied, V) / (current leakage, l).
2.AC Voltage Measurement
This is obtained from converting the value of the current flowing from the
voltage source through the instrument to a voltage value.
3.Low Resistance Measurement
The resistance of test object Rx is obtained by supplying a specific current l
to the test object and measuring the voltage occurring between the test ter-
minals using the formula (inter-terminal voltage, V) / (supplied current l).
To avoid corrosion from battery leakage, remove the batteries from the instru-
ment if it is to be stored for a long time.
Measurement Procedures
Display Function
Effective maximum
indicated value
250 V
500 M
Ω
500 V
1000 V 4000 M
Ω
To avoid electric shock, always verify the appropriate setting of the
function selector before connecting the test leads.
• When measuring insulation resistance, dangerous voltage is applied
to the measurement terminals. To avoid electric shock, do not touch
the test lead.
• Never touch the object being measured immediately after measuring.
There is a danger of electric shock from the change accumulating dur-
ing high voltage testing. (See Discharge Function)
• Discharge the subject conductor after measurement.
• Do not attempt to measure insulation resistance on a live conductor.
Doing so could damage the instrument or cause an accident that
might result in injury or death. Always turn off power to the conductor
being measured before starting
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