5-1 Preparation(1) To Check battery set the function/range switch (5) To the desiredposition. If the display is clear without symbol “B”showing,battery voltage is sufficient. If the display blanks or“B”isindicated, replace the battery in accordance with the batteryreplacement procedures as described in section 6.Note:“B”also appears on the display when the batterybecomes exhausted during use. Replace with a new battery.(2) Make certain that the data hold button is in the off position - notpressed down. If a measurement is made with the data hold buttonpressed in, the display remains locked irrespective of input.5-2 AC current MeasurementWARNING●Do not make measurement on a circuit above 600V AC.●Transformer jaw tips are designed not to short the circuit undertest. If equipment under test has exposed conductive parts,however, extra precaution should be taken to minimize thepossibility of shorting.●Do not make measurement with the battery compartment coverremoved from the instrument.●Keep your fingers and hands behind the barrier duringmeasurement.― 12 ―CAUTION●Transformers jaws , especially their tips, have been preciselyadjusted to obtain maximum accuracy. Take sufficient care toavoid shock, vibration or excessive force when handing theinstrument.●When a foreign substance is stick in the jaw tips or they cannotproperly engage, the transformer jaws do not fully close. In sucha case, do not release the jaw trigger suddenly or attempt toclose the transformer jaws by applying external force. Make surethat the jaws close by themselves after removing the foreignsubstance or making them free to move.●The maximum size of conductor that can be measured is approx.68mm in diameter. An accurate measurement cannot be madeon a conductor larger than this, because the transformer jawscannot be fully closed.●Frequency selector switch (9) is designed to select the 50/60Hzand“WIDE”frequency ranges. For further details, refer tosection 5-4 for operation of the frequency selector switch.●The transformer jaws may buzz when measuring large current.This has no effect on the instrument's performance or safety.(1) Set the function/range switch to the desired position. Do not exceedthe maximum allowable input current for the selected range.(2) For normal measurement, press the jaw trigger to open thetransformer jaws and clamp onto one conductor only. See Figure3. Earth leakage current or small current that flow through agrounded wire can also be measured by this method. (Fig. 4)If is recommended that the conductor is placed at the center of theclosed transformer jaws.(3) To measure out of balance leakage current, clamp onto allconductors except a grounded wire. The leakage current measurewill be indication on the display. (Fig.4&Fig.5)― 13 ―Note:When measuring large current, observe the time limit specified insection 3, Specifications. Otherwise, the transformers jaws may
overheat, resulting in damage to the instrument.
Fig.3 Normal AC Current
Measurements
Fig.4 Earth Leakage Current
Measurements
Single-Phase 2-wire system
(in 3-wire system with neutral
clamp onto all 3 wire)
3-phase 3-wire system.
(in 4-wire system with neutral
clamp onto all 4 wire)
Fig.5 Measurements out of balance Leakage
― 14 ―
5-3 How to Use Peak Hold Function
10ms or 100ms response time can be selected for peak hold
measurement. Make selection according to your application needs.
(1) With the transformer jaws clamped onto the conductor under test,
slide the peak hold switch from the OFF position to the desired
peak response time position.
(2) The peak hold display reads 1/√2 of the peak current value.
Therefore, an RMS reading will be obtained when the current
under test has a sinusoidal waveform.
I
(3) Slide the peak hold switch back to the OFF position for a reset.
Note 1:KEW SNAP 2413F uses an analogue peak hold circuit to
ensure a quick response to input current. Because of the
nature of this circuit, the peak hold reading may gradually fall
or, in a rare case, rise with time. This is likely to be apparent
when the instrument is used in a high temperature and high
humidity environment. Therefore, the instrument will not be
suitable for making peak measurement over an extended
period of time. In case of such a need, connect a recorder to
the instrument via the analogue output terminal.
― 15 ―
Note 2:If it is necessary to read the display away from the conductor
in a peak hold measurement, press the data hold switch (2)
first and then remove the instrument from the conductor.
Otherwise, the peak hold reading may be higher than the
actual value due to the electrical noise caused by the
opening and closing of the transformer jaws. Press the data
hold switch again for a reset.
(4) Difference between 10ms and 100ms Peak Response Time
The peak hold circuit in this instrument charges the peak-hold
capacitor after rectifying the input waveform. The time for the voltage
of the capacitor to reach its peak value varies according to its
capacitance and the output impedance of the charging circuit. KEW
SNAP 2413F sets the time for the voltage of the capacitor to reach
90% of its peak value to 10ma or 100ms by switching between two
output impedances. Refer to Figure 7 for further details.
I
For instance, select the 10ms response time when measuring a surge
current that will occur when a power supply device is switched on. The
100ms response time is recommended for measuring the starting
current of a motor or similar equipment. A stable measurement can be
made on the 100ms second response time setting as the peak hold
circuit does not readily respond to the surge current.
― 16 ―
5-4 How to Use The Frequency Selector Switch
KEW SNAP 2413F has a very good frequency response because of the
electromagnetic property of its transformers jaws. Therefore, it
measured, AC current not only of fundamental frequency of 50Hz or
60Hz, but of high frequencies and harmonics superimposed on the
fundamental frequency. To eliminate these superimposed components
and measure only in the fundamental frequency, KEW SNAP 2413F
has a high-cut filter circuit, which can be activated by activated by
setting the frequency selector switch to the '50/60Hz' position.
The high-cut filter has a cut-off frequency of approx. 100Hz and an
attenuation characteristics of approx. -24 dB/octave.
Note:-24dB/octave means that the magnitude of a signal declines by
a factor of 16 when its initial frequency doubles.
The frequency selector switch has the following two positions.
●WIDE(40Hz-over 1kHz):
Covers a wide frequency band from mains supply to high frequencies
generated by such equipment as inverters.
●50/60Hz(40-Approx.100Hz):
Filters out high frequency components to restrict measurement in
mains frequency band.
Note:Selection with the frequency selector switch dose not apply to
AC output of the two-way analogue output. DC output of the twoway
analogue output reflects the frequency selector switch
setting. Refer to Figure. 1 for frequency characteristics.
― 17 ―
5-5 How to Use Data Hold Function
Push in the Data Hold button to freeze the reading. This is especially
useful for taking a reading in a dimly lit or hard-to-reach locations. The
display can be observed away from the conductor. Push the button
again to release the reading.
5-6 Analogue Output: How to Use Model 7073 Output Cord
AC and DC output can be obtained by inserting optional Model 7073
output cord into the two-way analogue output terminal (3).
AC Output
Can be monitored by connecting a digital multimeter to analogue output
terminal or observed as a waveform by connecting an oscilloscope.
For true RMS measurements, connect a true-RMS-reading digital
multimeter.
DC Output:
Can be monitored by connecting a digital multimeter, or a recorder,
which enables many hours of monitoring. See Figure 8. With the 2413F
in the peak hold mode, DC voltage corresponding to 1/√2 of a peak
current value can be held and output.
Refer to section 5-3, How to Use Peak Hold Function.
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