Geovista Sonde Operations Manual
3 Arm Calliper Sonde
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3 Arm Caliper Sonde
Specifications
Recommended mnemonic CAL3
Sonde measurement parameters
Parameter Range Resolution Accuracy
Caliper Maximum 600mm 0.01mm +/- 5mm
Imon 0-255 NA Not Calibrated
Sonde Dimensions
Sonde length 1.37 metres
Sonde diameter 38 millimetres
Sonde weight 8.5 Kg
Communications Parameters
Channel No. Depth Recommended Recommended
Offset Mnemonic Unit
Calliper 10 cm CAL MM
Motor Monitor 10cm IMON MA
Head Voltage 10cm HEAD VOLT
Channel Description
Channel 1 is the caliper channel. This is calibrated into millimetres or inches as required.
When calibrating the sonde ensure that the expected range of borehole diameters lies
within the maximum and minimum diameters between which the sonde is calibrated. A
three point calibration is the preferred.
Channel 2 is a monitor of the current drawn by the motor when the caliper is opening or
closing. It is useful only as a diagnostic aid and is not usually displayed.
Channel 3 reports the head voltage measured inside the sonde. Again, this is a
diagnostic channel.
Safe Operation
In the event that, while closing the caliper sonde, borehole debris becomes trapped
underneath the arms, a stall condition can occur in the motor drive train. This has the
potential to cause damage to the drive parts.
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To prevent this, the sonde continually moniters the current drawn by the motor. If this
exceeds a predetermined value (equal to 150 bits in the uncalibrated data) then the sonde
will automatically disconnect power to the motor. The operator should be aware of this
possibility and moniter the caliper diameter reading so that the condition of the caliper is
understood and appropriate action taken.
Manual Revision Record
Version 1.0 May 2007 Author Seghir Messamah
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A Banana A
4mm Socket
2ACS_D
B B
AUX
Gnd
0V
Ref
W M+ B C D -M A
MC +VE MC-VE Line
2ACS_D
Pink
Black
White
+
Motor capacitor
C 2 C
1 3 Black Caliper Opening Switch
Red Pink
10K Potentionmeter 10nF
SW1
Pink
SW2 Switches are normally
White
A
closed.
-
White
MOTOR
Caliper Closing Switch
D D
GeoVista Ltd
Title 2 Arm Caliper Wiring Assembly 2 Arm Caliper
#6 Cae Ffwt Business Park
Sonde PCB
Glan Conwy, Conwy
Size: A4 Number: Revision: D
LL28 5SP
Date: 11/03/2004 Time: 14:46:29 Sheet of United Kingdom
File: \\Martin\c on martin\CLIENT\QED_DRAW\2ACS\2ACS_D\2ACS_D_3.schdoc
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