Aanderaa Recording Current Meter Compass Errors Caused by Mooring System Components.

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by
s.n , S.l
SeriesCanada Bedford Institute Report bi -- 1981-06
ContributionsKeenan, P.
ID Numbers
Open LibraryOL21892711M

Rate underreading of Aanderaa current meters fitted with paddle-wheel rotors has been attributed to rotor shielding, which was said to be caused by high-frequency mooring vibration (Loder and Hamilton ).It was postulated that this mooring vibration and the resulting current meter motion was caused by the flow-induced oscillation of in-line spherical buoyancy packages (Viny floats).Cited by: Best agreement was between the DVS and the nearby Seaguard (RMS speed difference of cm s(-1)), during the shelf deployment, and between the Aanderaa recording current meter.

These errors are usually caused by the current meter encoding circuits and, although never resulting in a parity error, they do follow a specific pattern.

Again, they Aanderaa Recording Current Meter Compass Errors Caused by Mooring System Components. book identifiable and easily corrected.

The combination of a low number of errors and their easy identification is key to the rapid process­ ing of these current meter data. The RCM Doppler Current Sensor is furnished with a new Hall effect compass and a two-axis tilt sensor that compensates for the effect of inclination.

This feature allows the instrument to be used in a mooring line with an inclination up to 35° from vertical. The instrument has a depth capacity of meters. The current speed and. Aanderaa Recording Current Meter 8 (RCM-8) is a self-contained insturment that can be moored into the sea and record ocean current, water temperature, conductivity of the water and instrument depth.

RCM-8 consists of a recording unit and vane assembly which is equipped with a rod that can be shackled into the mooring line. The mooring line oscillation depicted at left has been shown to cause significant current meter under-reporting.

When the mooring on the right is stabilized by using SUBS streamlined flotation, the data correlates very well with ADCP data recorded over the same time period. The data set improvement is very similar for both RCM-8 and S4 current.

Doppler Current Sensor (DCS) The Aanderaa Doppler Current Sensor is a rugged, true vector averaging current sensor for measuring current speed and direction in the sea. The sensor has built-in compass and tilt sensor and may also output sea temperature.

The speed range is 0 to cm/s. Low current drain and flexible sampling schemes. bottom-mounted Aanderaa recording Doppler current profiler (RDCP) to a string of seven moored Aanderaa RCM9 MKII single-point Doppler current meters, and an RDI kHz Workhorse ADCP.

Re-sults of vector correlations and difference statistics AUGUST DROZDOWSKI AND GREENAN a magnetic field causes a current to be induced in the coil opposite to the current that caused the movement of the coil.

This induced current will act to damp oscillations. In addition to this method of damping, which comes from the movement itself, most meters use a second method of damping.

The second method of damping used in most meter. A total of 20 current meters of seven different types were deployed on six moorings of four different designs. The instruments were grouped in four depth levels: level 1, m ; level 2, m ; level 3, m; and level 4, m ( m from the bottom).

Current meters were numbered in the form jk, where j is the mooring and k is the depth. velocity components to cancel when computing horizontal velocity. Also, pitch and roll cause velocity errors proportional to the sine of the pitch and roll.

The four beams allow for estimation of two perpendicular horizontal velocities and two vertical velocities. The direction of the vertical current is defined as positive upwards.

Two "Mini" current meters were anchored at 20 and 28 meter depths. The diatance to bottom was appr. A second mooring with two Aanderaa RCM- 7 current meters at identical depths was anchored 85 m away.

Fig. 4 shows the field situation. Page4. 1 2 CONTEI{TS ACKilOI{LEDGE}IENTS INTRODUCTION COASTAL OCEAIIOGRAPHY AND IIIIPLICATIONS FOR ¡iIOORED SYSTEI{S Strong currents Mari ne f ou'l i.

The unused terminals are protected but the additional signals may interfere with current measurements. For example, applying inputs to the 3A terminals while making measurements on the 10A terminals will typically cause errors.

Description Aanderaa Recording Current Meter Compass Errors Caused by Mooring System Components. FB2

Unnecessary signals applied to the Hi and Lo Sense terminals can also cause errors. An acoustic Doppler current profiler (ADCP) moored a few meters above the bottom at the m isobath out from Perth gave hourly data at 4-m depth intervals for little over an year (Figure 11).In December, there was strong northward alongshore flow due to the wind-driven Capes Current that lowered the temperature at the instrument by 2°C.

This was the first field test of the Ultramoor system and it lasted about months from August to November of All of the current meters on the mooring were located near m depth with a spacing of about 10 m (Fig.

1, Table 2) and all returned some data, although not all lasted through the full instruments available from this mooring for intercomparison are an ACM (see. evidence of persistent problems was found for the current meter other than the occasional glitch.

However, there was a high incidence of large kurtosis for the compass. This confirmed observations made during data recording that the compass channel. Remedies Such errors may be minimized by adopting a moving system of a light-construction and deflecting torque large (large torque-weight ratio and mounting the moving system on a vertical, rather than a horizontal spindle for preference between jewelled bearings).

The user can minimize frictional effects by tapping gently on the case with his. tain bubbles (air or gas) cause dynamic changes to a Coriolis meter that are not present in a single-phase fl uid and that lead to measurement errors. A Coriolis meter operates by “driving” one or two tubes at a resonant, or natural, frequency.

In the meter, the electronics (or transmitter) send a drive signal to the sensor that tracks. When evaluated, this strong current causes the mooring to lay over considerably. Shown to the left is the plot of the mooring forced with a single component current of 2 ms The major mooring components (i.e.

floats, current meters, acoustic releases. are plotted as special symbols on the mooring. [11] The compass at the lowermost current meter at mooring F2 (10 mab) functioned for a day period only. The average current values given in Table 2 are based on this period.

During this day period the directions given by the 10 mab instrument and the 56 mab instrument differed by only a few degrees at most. We have therefore. The typical current-meter mooring employed by the U.S.

Geological Survey is a subsurface taut-wire mooring (see Fig.

Details Aanderaa Recording Current Meter Compass Errors Caused by Mooring System Components. PDF

1), which consists of floats with sufficient buoyancy to suspend the weight of equipment and mooring cable, the current meter(s), an acoustic release, and a suitable anchor (normally kg).

All of these components are. The shunt resistor bypasses the extra current that the meter cannot carry. For example, to measure mA on a 1 mA meter the shunt resistor would have to carry mA leaving 1 mA to produce a full-scale deflection (fsd) on the meter. The lower the value of the parallel (or shunt) resistor the higher the current that can be read on the meter.

The force of the water coming into the building at the meter, turns the dial that keeps count of the usage. If you get a water bill that seems too high, more than likely it is not a faulty water meter, but a leak or a misread.

To determine if the water meter is in fact wrong, you must eliminate the other causes of. In order to assure protection of equipment, the system components must be applied within their short-circuit current (withstand) rating in accordance with NEC In order to verify this, the system components’ short-circuit withstand ratings must be known and the available fault current must not exceed these values.

Mechanical current meters are mostly based on counting the rotations of a propeller and are thus rotor current meters. A midth-century realization is the Ekman current meter which drops balls into a container to count the number of rotations.

The Roberts radio current meter is a device mounted on a moored buoy and transmits its findings via radio to a servicing vessel. The AMF model tape recording current meter is manufactured by the AMF Electrical Products Division of AMF, Inc., Alexandria, Virginia, and is based on a model designed and developed at the Woods Hole Oceano­ graphic Institution.

This instrument, which contains a Savonius rotor, a direction vane, a magnetic compass, and a thermistor. • Each meter is assigned a unique number for each customer location. Data from a customer’s location is matched with the meter number assigned to that location before it’s sent to our billing system for processing.

• It’s important to remember with AMR meters, we will continue to capture the same. 2 figure 2. northern current meter mooring deployed at station a-9 4 figure 3. northern current meter mooring design showing location of damage 5 figure 4a.

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photograph of aanderaa current meter spindle showing break (lower left end) at the bearing support, resulting in loss of meter 6 figure 4b.

All meters must be factory programmed to begin recording kWh and kW upon installation. Meters must have Modbus TCP/IP data output communications capability for Ethernet Network connection to current Eielson AFB automatic meter reading system (AMRS).

Meters must be installed indoors in electric room and be wired to the base CE. The present invention relates to profiler systems and methods for observing and sensing aspects of a body of water at a plurality of depths. A water profiler is disclosed comprising, generally, a vessel body connected to an external mooring cable via an attachment means, a drive means for maneuvering the vessel body longitudinally about the mooring cable; an articulating mechanism; and a.Performance Audit: Water Meter Reading, Estimates, and Adjusted Billings May City Auditor’s Office City of Atlanta File #Full-scale meter voltage sensitivity, important in any current meter used with an external shunt, is meter current times meter resistance.

If the meter is 1 mA and has 50 ohms resistance, full-scale sensitivity is amperes*50 ohms volts, or 50 millivolts FS.

50 millivolts is a very common meter .