ZH instruments SM-30 User manual
ZH instruments
Magnetic susceptibility meter
SM-30
USER’S MANUAL
Publication Date: June 2010
ADDRESS
Zdeněk Hůlka
ZHinstruments
Kárníkova 22
621 00 Brno
Czech Republic
Tel. + Fax: +420 - 541634297
GSM.: +420 - 603795973
E-mail: zhinstruments@email.cz
Web: www.zhinstruments.cz
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1.GENERAL INFORMATION...................................................... 4
1.1 Application........................................................................... 4
1.2 Specification ........................................................................ 5
2. DESCRIPTION OF INSTRUMENT .......................................... 6
2.1 General description............................................................... 6
2.2 Operating principles.............................................................. 7
2.2.1 Basic modes A and B ...................................................................... 8
2.2.2 Extrapolation mode........................................................................ 9
2.2.3 Interpolation mode ...................................................................... 10
2.2.4 Scanning mode............................................................................. 10
2.2.5 Averaging mode ........................................................................... 11
2.2.6 Comparison of modes................................................................... 11
3. OPERATION....................................................................... 14
3.1 Switching instrument ON and OFF .........................................14
3.2 Setting and indication of mode ..............................................15
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3.3 Measuring susceptibility of rock .............................................15
3.3.1 Basic modes A, B.......................................................................... 15
3.3.2 Extrapolation mode...................................................................... 16
3.3.3 Interpolation mode ...................................................................... 17
3.3.4 Scanning mode............................................................................. 19
3.3.5 Averaging mode ........................................................................... 21
3.4 Memory registers ................................................................22
3.5 Battery replacement ............................................................24
3.6 Communication with computer ..............................................25
3.6.1 General information ..................................................................... 25
3.6.2 Instrument operation using computer.......................................... 25
3.6.3 Transfer of data to computer........................................................ 26
3.7 Error messages ...................................................................28
4 FIGURES............................................................................. 30
4.1 Figure 1 .............................................................................30
4.2 Figure 2 .............................................................................31
4.3 Figure 3 .............................................................................32
4.4 Figure 4 .............................................................................33
4.5 Figure 5 .............................................................................34
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4.6 Figure 6 .............................................................................35
4.7 Figure 7 .............................................................................36
5.APPENDICES ...................................................................... 37
5.1 SM30 software ....................................................................37
5.2 SM30 programme for Windows 95/98/NT/2000 .......................37
5.2.1 Running the program ................................................................... 37
5.2.2 Reading memory registers ........................................................... 38
5.2.3 Communicating with the computer on-line................................... 38
5.2.4 Handling the charts...................................................................... 39
5.2.5 Saving the data ............................................................................ 40
5.3 Finite thickness layer correction ............................................41
5.4 Conductivity effect...............................................................42
5.5 The demagnetisation factor correction....................................44
5.6 Drill Core correction factor ....................................................45
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1.GENERAL INFORMATION
1.1 Application
The SM-30 meter is intended for measuring the magnetic susceptibility of rock.
Owing to its high sensitivity, it is capable of measuring rock with a very low
susceptibility. It can also measure diamagnetic substances. The meter reaches its
peak sensitivity within a very few seconds after switch-on. By employing a very
sophisticated way of processing the signal, the meter can efficiently reduce the
influence of external electromagnetic disturbances and the noise of electronic
circuits. Its low wei
g
ht and small size make this instrument ideal for use
out-of-doors.
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1.2 Specification
SENSITIVITY…………………………………………………………………………………….1x10-7 SI Units
MAX MEASURED VALUE…………………………………………………………………………………..….1SI
DIMENSIONS……………………………………………………………….……………..100 x 65 x 25 mm
WEIGHT………………………………………………………………………………………….……………0.150 kg
OPERATING FREQUENCY………………………………………………………………………………..…8kHz
MEASUREMENT TIME
…………………………………………………………………………………….basic mode approx. 5s
…………………………………………………………………..drift correction modes approx. 8s
DIGITAL DISPLAY………………………………………………………………….LCD 4digit,10mm high
CONTROLS…………………………………………………………………………………………3 push buttons
DATA MEMORY………………………………………………………………….up to 250 measurements
PICK-UP COIL SIZE 50 mm in diameter
OPERATING TEMPERATURE……………………………………………………………..-20oC to +50oC
BATTERY……………………………………………………………….….…….2 Lithium 3V type CR2430
BATTERY LIFE…………………………………………………………….………………..typically 80 hours
COMMUNICATION WITH COMPUTER……………………………………………………………..RS232
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2. DESCRIPTION OF INSTRUMENT
2.1 General description
The susceptibility meter is enclosed in a box, which has a front panel with push
buttons and a four-digit 10mm character display. In order to get the right value
in SI, the user must multiply the reading by a constant 10-3.
Behind the front panel there is a buzzer, which monitors by way of acoustics the
operation of the meter. On the right-hand side of the cover there is a connector
for communication with a computer. A communication cable is delivered as part
of the set. On the bottom side of the cover there is a little cubicle holding two Li
batteries.
The 50mm pickup coil is placed on the left-hand side parallel with the bottom
part of the cover (see figure 6).
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2.2 Operating principles
The meter contains an oscillator with a pickup coil. The frequency of the oscillator
depends on the distance of the meter from rock. the change in frequency is
proportional to the amount of susceptibility of the rock. In order to find out about
the change, it is necessary to measure the oscillator frequency twice. The first
measurement is performed near the rock. This is called pick-up step.
The second measurement is carried out when the meter is away from the rock
(free air measurement). The second phase is called compensation step.
After the second step is finished, both values are subtracted and displayed. Both
the steps are initiated by the operator.
The above mentioned mode is called basic mode or mode 1.
When measuring rock of very low susceptibility, it is possible that the oscillator
thermal drift becomes greater than the effect of the rock. In this case it is
necessary to measure not only the susceptibility, but also the thermal drift. The
thermal drift and susceptibility values are then compared. The thermal drift
measurement requires that two measurements away from rock are carried out,
which means that there have to be three steps altogether. Two steps are
performed without rock and one is performed with rock. The SM-30 meter offers
two ways of correcting the drift. The first mode is called extrapolation mode or
mode 2.
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The second mode is called interpolation mode or mode 3.
When measuring places that are situated very close to one another, it is best to
use scanning mode.
This mode corrects the thermal drift as well and the measurement is very quick,
although the drift correction is not so precise as in the extrapolation or
interpolation mode.
2.2.1 Basic modes A and B
The function of the meter is shown in Figure 1a. Figure 1b shows the way the
oscillator frequency is affected by the measured object. It also shows the
frequency difference in both the steps. The difference is used as ground for the
calculation of magnetic susceptibility. Figure 1 deals with an ideal case, when
there is no thermal drift. Susceptibility is calculated using the formula
susc = f2- f1
After the compensation step is finished, the value susc is displayed.
Figure 2 shows the effects of thermal drift during Basic mode. It shows that the
oscillator frequency is not only influenced by the measured rock during the
pickup step, but it changes without any apparent reason and causes
measurement error.
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