4
2-4 Explanation of functions
1. Overflow (O.L.) value
• The O.L. mark appears on the readout when the input value exceeds 4,000 counts in each
measurement range with the manual mode selected. It does not appear in the 750 VDC or VAC
range.
• The O.L. mark appears when the maximum measurement range exceeds 4,000 counts with the
auto mode selected. You need to note that the O.L. mark does not appear in the voltage mode.
• When the measurement connector is released, the O.L. mark appears in the Ω,
, or
mode.
2. Sounding of buzzer
• The buzzer sounds momentarily when the Range Hold, Data Hold, or Select switch is pressed.
• In the mode, the buzzer sounds when a resistance value is below 10-120 Ω (which varies
individually).
3. Counts
• Regardless of the position of the decimal point, the value on the readout is represented by
"counts." (2dgt and 5dgt as shown in the column on the previous page are equivalent to 2
counts and 5 counts, respectively.)
4. Accuracy
• Accuracy as used in "2-3 Specification" is represented by the sum of certain percentage of ±
rdg (reading) against the value shown on the PC20TK (measured value) plus certain ± counts
dgt (digits).
• [Calculation example]
Now let us check the accuracy assuming that the reading was 106.6 V when certain standard
voltage (true value) was measured in the 400 VAC range of the PC20TK.
The accuracy of the 400 VAC range of the PC20TK is ± (1.5 %rdg + 5dgt).
1dgt in the 400 V range is equivalent to 0.1 V. Hence,
(±1.5 %×106.6 V) + (±0.1 V×5) = (±1.6 V) + (±0.5 V) = ±2.1 V
The true value therefore exists in the range of 106.6 V ± 2.1 V = 104.5 to 108.7 V (provided that
it falls within the accuracy-warranted temperature and humidity ranges and that for AC, it is of
sinusoidal AC within the range of 40 to 400 Hz). If the true value does not fall within these
ranges, the reading on the PC20TK deviates from the standard.
5. Sampling rate
This is the number of times when an input analog signal is converted into a digital one per
second by the analog-digital converter.
6. Low power ohm
Silicone transistors and diodes are generally brought into complete conduction at voltage of
about 0.7 V. Measurements using voltage that does not cause such conduction (0.4 V maximum
in general) are called low power ohm measurements. Low power ohm measurements allow you
to perform resistance measurements and conductivity checks in the circuit network with the
minimal effects of transistors and diodes.
7. Data holding capability (DH: Data Hold)
Pressing the Data Hold switch during measurement locks the reading on the readout regardless
of changes in input signal (the DH mark appears on the readout).
8. Range hold capability (Range Hold)
• Auto mode
The suitable range for the current input signal is automatically selected (the AUTO mark
appears on the readout).
• Manual mode
In this mode, the user should press the Range Hold switch to select the suitable range by
predicting the magnitude of input signal. The measurement range will be locked (held) and the
AUTO mark will disappear. In this state, pressing the Range Hold switch toggles between
ranges. If this switch is held down exceeding 1 second, the manual mode is canceled and the
auto mode becomes active.
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