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REFERENCE
*Effective Value (RMS)
Most alternating currents and voltages are
expressed in effective values, which are also
referred to as RMS (Root-Mean-Square) values.
The effective value is the square root of the
average of square of alternating current or voltage
values. Many clamp meters using a conventional
rectifying circuit have "RMS" scales for AC
measurement. The scales are, however, actually
calibrated in terms of the effective value of a sine
wave though the clamp meter is responding to the
average value. The calibration is done with a
conversion factor of 1.111 for sine wave, which is
found by dividing the effective value by the
average value. These instruments are therefore in
error if the input voltage or current has some other
shape than sine wave.
*CF (Crest Factor) is found by dividing the peak
value by the effective value.
Examples:
Sine wave: CF=1.414
Square wave with a 1: 4 duty ratio: CF=2
4. DISPLAY
Low
~
= –
Battery
1.8.8.8
Warning
B ATT
NCV
5. PREPARATION
Check battery voltage.
Set the Function selector switch to the position
other than OFF position.
Battery Voltage is enough if indications are
displayed clearly and "BATT" mark is not
displayed on the LCD. If "BATT" mark is
indicated or no indication on the LCD, replace
batteries with new one according to battery
replacement procedures shown in clause 8 in
this document.
Data
Hold
AC/DC
Mode
H
X
Unit
NCV Range
CAUTION
!
• Indications may not being displayed on the
LCD despite the function selector switch is at
the position other than OFF position. This is
because power-off function operated
automatically and the instrument turned off.
• Power off function can be released by turning
the function selector switch to OFF, and then
set it to the range on which you would like to
make a measurement. If LCD still blank,
batteries are completely exhausted. Please
replace batteries.
• Check the function selector switch is set to the
appropriate range. And also check data hold
function is not enabled. If inappropriate range is
selected, desired measurement cannot be
made.
6. MEASUREMENTS
6-1 Current Measurement
DANGER
!
• To avoid getting an electrical shock, never make
measurement on the circuit in which electrical
potential over AC/DC300V exists. Do not make
measurement with battery cover removed.
CAUTION
!
Max. diameter of measured object(conductor) is Ø
10mm.
Correct
Incorrect
Place the center of the metal conductor lower than the
triangle mark indicated on the fork shaped sensor.
(shaded part in the figure)
6-1-1 DC current measurement
1- Set the function selector switch to " A "
–
position. ("
" and "A" marks will be displayed
- --
on the LCD.)
2- Press HOLD/0ADJ button for 2 sec or more to
enable 0ADJ function and adjust the indication
on the LCD to be 0. (Indication shall be
adjusted to 0. Otherwise, error occurs.)
3- Place one measured conductor lower than the
triangle mark indicated on the fork shaped
sensor and make a measurement. (shaded part
in the figure)
Then measured value is displayed on the LCD.
(When the center of the conductor is not lower
than the triangle mark indicated on the fork
shaped sensor, error occurs.)
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