Electronic Fluxmeter EF 14
range of the integrator is not exceeded and the inductance of the measuring coil can be
neglected.
In AC RMS mode the output voltage of the integrator is supplied to an integrated circuit that
generates the root mean square (RMS) of the alternating voltage. This converter requires a
minimum amplitude of about 3 % of the full range limit to generate a valid reading. If the
reading is below this limit this is announced by a downwards pointing arrow above the unit.
Additionally the amplitude of the flux must be below the full range limit to avoid a range
overflow. This means for a sinusoidal waveform that the RMS value must be below the full
range limit divided by
2
. If the RMS value is above this limit this is announced by a upwards
pointing arrow above the unit. The RMS converter limits also the frequency response; an
accuracy of ±5 % is maintained in the range of 10 Hz < f < 5 kHz.
The functions Max./Min. and Peak can also be used in AC mode. Max./Min. shows the
maximum RMS.
If the peak function is enabled in AC mode, the EF 14 shows the peak value of the measured
flux waveform (and not the peak value of the RMS). The analog peak hold circuit is active but
the peak value is not digitally stored. Therefore it will follow slowly the amplitude of the
waveform if this decreases. Pressing Reset causes fast settling to a changed amplitude.
5.4 Measuring Rate
Depending on the mode of operation, the EF 14 uses different measuring rates.
Normal operation, Peak off:
In this mode the A/D converter performs a conversion every 187 ms. The display shows the
average of two subsequent measurements, thus it is actualized every 374 ms. The same values
can be requested from the computer interface. The Max. and Min. values are also derived from
these values and actualized in the same time interval.
Normal operation, DC, Peak on:
Peak and valley are captured by fast analog circuits that are alternating sampled by the A/D
converter. The displayed values are alternating actualized, each of them every 748 ms. There is
no averaging.
Fast data mode:
In this mode the A/D converter uses a faster sample rate that can be selected using the interface
command #SPEED x (see chapter 6.3.1). The parameter x of the command determines the
interval between two measurements in steps of x · 0.732 ms. Values of 254 (lowest speed,
approx. 5.4 measurements per second) to 27 (highest speed, approx. 50 measurements per
second) are possible. The measured values are transferred with this rate thru the interface. The
normal operation can be restored with #SPEED 255.
The display cannot be actualized that fast and is therefore deactivated in the fast data mode. The
functions Max./Min. and Peak are not available. The keypad operation is completely blocked.
The operation from the digital control lines is also impossible. The fast data mode setting is not
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