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It could be a problem connected to the power supply given by the readout or logger. When the power supply is in the current loop (2-wire gauge) it is necessary to consider the effect of voltage drop across the shunt resistor on the voltage applied to the gauge.
For example, suppose a 4-20mA gauge requires at least 12 V to operate correctly and the readout powered with 16 V. The voltage the gauge sees is the voltage supplied by the readout minus the voltage drop in the rest of the current loop. At 20 mA output, the voltage drop across the commonly used 100 ohm resistor is 2 V.
When the voltage supplied by the readout is 16 V, this leaves 14 V for the gauge and everything is fine.
However, if the readout is powered with less than 14 V, at 20 mA current it will leave less than 12 V for the gauge. In this case, the output of the transmitter may be in error.
FAQ#110 - What's the purpose of the linear and polynomial factors written in the Calibration Reports?
Utilize the Linear Sensitivity Factors (A, B) and Ploynomial Sensitivity Factors (A, B, C, D) of the Calibration Reports permit to obtain readings in engineerig units with a maximum error as for the Calibration Report.
In the case of analogue gauges, the factors shall be applied on the electrical readings (i.e. mA, mV, digit, etc...)
In the case of digital gauges in "Legacy mode" (digital gauges with FW version 0.X, 1.X, 2.X or 3.X), the factors shall be applied on the output in engineering units (i.e. sin angle, kPa, etc...)
In the case of digital gauges in "Normal Mode" (digital gauges with FW version 3 or higher), the factors are already applied inside the gauge, so the Sensitivity Factors shall not be utilized with these instruments.
For more information regarding SISGEO Calibration Report, refer to the following video https://youtu.be/BF8e3ZRcaYU
For more information on "how to use" the Sensitivity Factors with analogue gauges and with digital gauges in Legacy Mode, refer to the instruments manuals or to the following document: https://www.sisgeo.com/uploads/manuali/Addendum_data_processing/ADDENDUM_-_DATA_PROCESSING_-_EN_00.pdf
All SISGEO digital gauges can be settled in two different powering mode:
- ALWAYS ON: all digital sensors switched on together. Faster solution, but high power consumption. The system will take about 1 second to read each gauge.
- TIMED: the sensors are powered and switched-on one by one. Reading of the chain take more time than "always on", but the power consumption is lower. In this case the system will take about 3 seconds to read each gauge.
The STANDARD powering mode is ALWAYS ON, so unless otherwise requested by the Customer, the sensors are settled as default in ALWAYS ON.
Sisgeo suggest that frozen water within the inclinometer casings is to be avoided due to following reasons:
- Ice within the casing will affect functionality of the systems by blocking the individual probes;
- Mechanical damages can occur to the probes, but also to the inclinometer casing due to the expansion of frozen water
In any case, inclinometers and DEX probes can work until -30°C so that sensors will be not damaged.
What can be done to avoid this?
- insert a heating cable that keeps water temperature above 0°C;
- remove water from the inclinometer casing;
- place the inclinometer/DEX probes at locations where temperatures remain above 0°C.
La massima lunghezza del cavo strumentale dalla sonda DEX al datalogger è 200m. Se il sistema di acquisizione dati include i multiplexer box esterni (architettura distribuita), la massima lunghezza del cavo è 200m dalla sonda DEX al multiplexer box esterno più altri 200m dal multiplexer box esterno a OMNIAlog (in totale 400m)
The cable lengths depend from many factors, first of all installation and cable protections (screen, earth, etc...). Assuming that instruments are installed in a workmanlike, for the maximum cable lengths should be followed the next suggestions:
DIGITAL INSTRUMENTS: see FAQ#073
ANALOGUE INSTRUMENTS: see both documents:
Cable length guide line with internal multiplexers
Cable length guide line with external multiplexers
FAQ#037 - Which is the linear thermal expansion coefficient of the graduated flat cable (tape) of Water Level Indicators (WLI) and BRS settlement probes?
The linear thermal expansion coefficient of the flat graduated cable is 16x10E-6 m/ °C.
The profiler consists of:
- a stainless steel measurement sensor for pressure measures;
- a cable reel containing the liquid tank;
- an electro-hydraulic cable for signals transmission;
- a tripod on which the reel/tank should be positioned.
The electro-hydraulic cable follows the probe (measuring sensor) to which it is connected. A small steel cable to pull the profiler probe is also provided; it should be situated into the same HDPE tube where the probe pass through (readings with two operators with both sides of HDPE tube accessible) or in a second tube located parallel to the first one (readings with one operator or one not-accessible side; in this last case a pulley system is recommended).
Finally, what you need to execute readings with the profiler is only a probe in HDPE with diameter ≥ 50 mm. We suggest you the HDPE and not a metallic tube because this kind of tube (without crash-it) must be adapted to the embankment differential settlements. It is advised to use a HDPE tube with diameter which is not more than 50mm to avoid mistakes or less accuracy in readings.
DEX system has been designed for automatic soil settlement monitoring (vertical movement) in unattended location. DEX system consists of a string of DEX probes installed in borehole within a ABS inclinometer casing. DEX-S, the combined inclinometer-settlement probe, provides both horizontal movements (X, Y-axis) and vertical settlement (Z-axis) for 3-D borehole automatic profile monitoring.
The arms of the spider only keep the magnet in place while grouting, but the grout couples the magnet to the surroundig soil. Grout mix shall be controlled (ratio water/cement) during grouting operation according to the soil application.
Sisgeo liquid mix is de-aired at factory and it is supplied sealed in special tank. However in the DSM reference gauge there is a high sensitive sensor which is able to monitor the weight of the liquid within the reservoir. In the case of the air bubbles come over decreasing the level of the liquid in the reservoir the sensor measures this change. Thus air bubbles are not usually a problem.
FAQ#010 - Which is the freezing temperature of the Sisgeo liquid mix for H-Levels LLS and Multipoint Settlement Systems system liquid?
Sisgeo liquid is a mix of 50% glycerin and 50% water. This mix have a freezing temperature of about -23°C.