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Topic: Loop Current


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In the News (Tue 22 Dec 09)

  
  Current loop - Wikipedia, the free encyclopedia
Current loops can be used over moderately long distances (tens of kilometres), and can be interfaced with optically isolated links.
Current loop interfaces usually use voltages much higher than those found on an RS 232 interface, and cannot be interconnected with voltage-type inputs without some form of level translator circuit.
For industrial process control instruments, analog 4-20 mA and 10-50 mA current loops are commonly used for analog signaling, with 4 mA representing the lowest end of the range and 20 mA the highest.
en.wikipedia.org /wiki/Current_loop   (595 words)

  
 Loop Current - Wikipedia, the free encyclopedia
Part of the Gulf Stream, the Loop Current is a warm ocean current in the Gulf of Mexico that comes up from between Cuba and the Yucatán peninsula, moves north into the Gulf of Mexico, then east and south through the Florida Straits.
Sea surface level of both the Eddies and the Loop on September 21, 2005 was up to 60 cm (24 in) higher than surrounding water, indicating a deep area of warm water beneath them.
In the Gulf of Mexico, the deepest areas of warm water are associated with the Loop Current and the rings of current that have separated from the Loop Current commonly call Loop Current eddies.
en.wikipedia.org /wiki/Loop_Current   (893 words)

  
 Magnetic field - Wikipedia, the free encyclopedia
In the equation above, the current vector i is a vector with magnitude equal to the scalar current, i, and direction pointing along the wire that the current is flowing.
The direction of magnetic field lines is defined as the direction of orientation of magnetic dipole—say, a small magnet or a loop of current in the magnetic field.
The "north" and "south" poles of a magnet or a magnetic dipole are labelled somewhat confusingly in comparison to the geographic north and south poles.
en.wikipedia.org /wiki/Magnetic_field   (1691 words)

  
 current liability - Hutchinson encyclopedia article about current liability
Amount a business owes currently to its creditors and suppliers that falls due within one year from the balance sheet date.
Current liabilities are short-term business commitments such as creditors (including employees), bank overdrafts, dividends, tax, and interest, and they normally require a company to convert some its current assets into cash to pay them off.
Current liabilities are not to be confused with long-term liabilities such as debt that is not due for over a year.
encyclopedia.farlex.com /current+liability   (149 words)

  
 Loop current (Floyd Davidson)
If the current was 35ma at the CO it is either going to be 35ma at the subscriber or (no not "wire loss and capacitance") there is a short to ground or between the pairs of _significant_ proportions to allow only 18ma at the subscriber location.
Current is. With a maximum loop current of 120 ma, the maximum power that will be dissipated in the resistor is.12 *.12 * 600, which works out to more than 8 watts of power.
In fact, loop current for offhook is specified at 23 ma or greater, with 60 ma as a recommended high and 120 ma as an absolute high.
yarchive.net /phone/loop_current.html   (3762 words)

  
 [No title]   (Site not responding. Last check: 2007-10-20)
Current is supplied from a current source in the control room and the transmitter controls the current from its location in the field.
The quiescent current draw of the feature module electronics 50 can also be determined by measuring the voltage drop across a current sensor resistor or by measuring the total quiescent current draw of the transmitter 12 and subtracting the measured quiescent current draw of the sensing module electronics 52.
For example, if the quiescent current draw of the device has reached or is training in a direction in which loop will cease to function, the device can transmit a warning of impending failure and/or disconnect itself from the loop such that the loop can continue to operate.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=05/17544.050224&ELEMENT_SET=DECL   (5534 words)

  
 PHY 207 Chapter 28 Direct-Current Circuits / Dr. Miner
When a battery is placed in a circuit loop with other circuit elements, such as capacitors or resistors, a DC current flows.
Here V is the terminal voltage (measured between the twoterminals), emf is the true emf of the battery, I is the current being drawn from the battery, and r is the battery's internal resistance.
If we keep track of the voltage around the loop, and remember that voltage (or potential, or electric potential) is potential energy per unit charge, we note that the sum of the potential changes (or potential "drops") around the loop must be zero.
www.udayton.edu /~physics/gkm/p207ch28.htm   (2072 words)

  
 Magnetic Field of a Current Loop
Electric current in a circular loop creates a magnetic field which is more concentrated in the center of the loop than outside the loop.
The current used in the calculation above is the total current, so for a coil of N turns, the current used is Ni where i is the current supplied to the coil.
The application of the Biot-Savart law on the centerline of a current loop involves integrating the z-component.
hyperphysics.phy-astr.gsu.edu /hbase/magnetic/curloo.html#c3   (220 words)

  
 Deepwater: Physical Oceanography Overview
Circulation in the eastern Gulf is dominated by the Loop current, which is a western boundary current in the Caribbean.
Total transport in the Loop current is approximately thirty million cubic meters per second with a variance of about ten percent.
Current meters at 500 m in the western Gulf showed velocity spikes to 30-40 cm/s.
www.mms.gov /eppd/sciences/esp/programs/deepwater/phys-o.htm   (372 words)

  
 Current Loop Application Note: 4.0 What Isn't Digital Current Loop
The purpose of 4 to 20 mA analog current loop is to transmit the signal from an analog sensor over some distance in the form of current signal.
The remote sensor regulates the loop current such that the loop current represents the value of the parameter being measured by the sensor.
A series resistor RL at loop power supply converts this current to a voltage that can be used by the electronics to record or distribute the parameter being measured.
www.bb-elec.com /tech_articles/current_loop_app_note/not_digital_current_loop.asp   (297 words)

  
 Mesh and loop current methods
Satisfying Kirchhoff’s current law is achieved by assigning closed current loops called mesh or loop currents to each independent loop of the circuit and using these currents to express all the other quantities of the circuit.
Since the loop currents are closed, the current that flows into a node must also flow out of the node; so writing node equations with these currents leads to identity.
In other words, if a current flowing through the resistor has the same direction as the mesh current of the loop, it has a positive sign, otherwise a negative sign in the sum.
www.tina.com /course/15mesh/mesh.htm   (1281 words)

  
 Telephone Basics - Subscriber Loop
AKA Line, local loop Included is the circuitry dedicated to a line in the Dial Central Office (DCO) switch, overvoltage protection at the frame and sometimes at the subscriber end, the pair of wires, and the terminal equipment (TE) which could be a telephone, modem or fax.
The amphour size of the batteries is decided by the current used by the switch, how long the the system should operate without AC power, whether or not there is a backup generator, etcetera.
For economy, the transmit voice, receive voice, loop current, ringing and the various tones are passed between the switch and the telephone on two wires called a pair.
www.yarker-dsyc.info /Notebook/TekStuff/Telefon/LocalLoop.html   (820 words)

  
 Multi-loop Circuits and Kirchoff's Rules
The currents have been labeled in each branch of the circuit, and the directions are shown with arrows.
There are three loops to use in this circuit: the inside loop on the left, the inside loop on the right, and the loop that goes all the way around the outside.
If one or more of the currents was known (maybe the circuit has an ammeter or two, measuring the current magnitude and direction in one or two branches) then an unknown battery emf or an unknown resistance could be found instead.
physics.bu.edu /py106/notes/Kirchoff.html   (1497 words)

  
 Loop Current and Circuit Loss Tech Bulletin
Loop Current is the amount of electrical energy flowing through the telephone and line, as opposed to the voltage which is the force behind the energy.
At the end of a long loop, the current that left the CO at 35ma might be 18ma because of wire loss (resistance), and the audio level may be well below -8.5db, causing it to be hard to hear.
Since loop current measurements are not usually exactly the same line to line, you should repeat the process for each line.
www.sandman.com /loopcur.html   (6457 words)

  
 General Purpose Small Vertical Loop Antennas for 160 - 10 meters   (Site not responding. Last check: 2007-10-20)
This 14-foot circumferential loop is performing as a small directional loop on frequencies of 40 meters and lower in frequency, and as a somewhat poor omnidirectional intermediate-sized loop on bands higher than 40.
Multi-turn loops of this type are less efficient, but you may have no choice to wind a smaller loop with multi-turns if you can't find the space for a single-turn, such as with indoor applications.
Rectangular loops might also be considered if you have a lot of vertical or horizontal space, but not much of both at the same point.
www.greertech.com /gpmag/gpmagloop.html   (2869 words)

  
 Multi-loop Circuits and Kirchoff's Rules
It is often useful to measure the voltage or current in a circuit.
To prevent the voltmeter from changing the current in the circuit (and therefore the voltage across the resistor), the voltmeter must have a resistance much larger than the resistor's.
The current is shown negative because it is opposite in direction to the current when the capacitor charges.
physics.bu.edu /~duffy/PY106/Kirchoff.html   (2280 words)

  
 Gulf Currents That Turn Storms Into Monsters - New York Times
In past decades, the current and swirling rings of warm water that it casts off have been tracked mainly for fishing fleets seeking the tuna and swordfish that congregate nearby, and oil companies worried that the roiling currents could rip their drill rigs out of the seabed.
Schaudt first became aware of the loop current's potential to nourish hurricanes in 1985, when he helped run a research project in which a small research vessel, the Pelican, was probing one of the warm eddies spun off by the loop south of Louisiana.
But when such a storm passes over the loop current or one of its eddies, the water can be 79 degrees as much as 300 feet deep, meaning that no matter how much a passing hurricane stirs things up, it never exhausts its fuel supply.
www.nytimes.com /2005/09/27/science/earth/27loop.html?ex=1285473600&en=c80076ffe523f5e0&ei=5088&partner=rssnyt&emc=rss   (1099 words)

  
 Sypris Test & Measurement | Closed Loop Current Sensors
A closed loop current sensor consists of a Hall generator mounted in an air gap of a magnetic core, a coil wound around the core and a current amplifier.The current carrying conductor placed through the aperture of the sensor produces a magnetic field that is proportionate to the current.
The current through the coil produces an opposing field to that provided by the current through the aperture Thus the flux in the core is constantly driven to zero.
The current output is converted to a voltage by connecting a resistor to the output of the sensor and ground.
www.belltechinc.com /stm/content.asp?page_id=673   (233 words)

  
 Loop Current   (Site not responding. Last check: 2007-10-20)
The Loop Current is the large flow of warm water that dominates circulation within the eastern Gulf of Mexico.
The Yucatan Current enters the Gulf of Mexico via the Yucatan channel, and is connected to the Florida Current (which flows out of the Gulf of Mexico between Key West and Cuba) by the Loop Current.
The seasonal circulation pattern of the Loop Current, is thought to be significant in the initiation, transport and retention of Gymnodinium breve blooms (Tester and Steidinger 1997); the study of the Loop Current contributes to our knowledge and understanding of general circulation patterns, and to the relationships between physical and biological oceanographic processes.
www.csc.noaa.gov /crs/definitions/loop_current.html   (187 words)

  
 ET420 - 4-20 mA Loop Current Receiver
Each channel is equipped with a large LED indicating the current loop status.
The input excitation is electronically short circuit and reverse polarity protected thus any short condition in one loop will not affect the operation of other devices.
Each loop has a jumper allowing for fast loop circuit disconnect and convenient loop current measurement with an in-line mA meter.
www.elkor.net /et420.htm   (278 words)

  
 Current Loop   (Site not responding. Last check: 2007-10-20)
Current Loop is a serial interface, which is used to transport data over long distances.
Since a current is used to transmit data there is a need for a loop, hence the name.
A Space is represented by the absence of current and a Mark is represented by a current running through the circuit.
ckp.made-it.com /currentloop.html   (234 words)

  
 Loop Current Eddies in the Gulf of Mexico, Quarterdeck 6.1   (Site not responding. Last check: 2007-10-20)
Dark purple areas indicate anticyclonic Loop Current eddies A, B, and C moving through the gulf.
George Born and Robert Leben of the University of Colorado used data from satellites TOPEX/POSEIDON and ERS-2 to track the location of the Loop Current, and to monitor the anticyclonic eddies that periodically separate from its northward intrusions into the eastern Gulf of Mexico.
The Loop Current shed a series of three such anticyclonic eddies in 1996, but throughout the year a broad area of cyclonic, lower than average sea-surface height remained in the northeast corner of the gulf.
www-ocean.tamu.edu /Quarterdeck/QD6.1/spin.html   (356 words)

  
 Physics Tutoring: Electromagnetic Induction   (Site not responding. Last check: 2007-10-20)
When the bar magnet is moved closer to, or farther from, the loop, an electromotive force (emf) is induced in the loop.
The ammeter indicates currents in different directions depending on the relative motion of magnet and loop.
Lenz's Law: An induced current has a direction such that the magnetic field of the current opposes the change in the magnetic field that produces the current.
www.slcc.edu /schools/hum_sci/physics/tutor/2220/em_induction   (678 words)

  
 Loop Current Method   (Site not responding. Last check: 2007-10-20)
The independent current variables are taken to be the circulating current in each of the interior loops.
Depending on the problem, it may ultimately be necessary to algebraically sum two loop currents in order to obtain the needed interior branch current for the final answer.
Example: Use the loop current method to determine the voltage developed across the terminals AB in the circuit shown in figure 1.7.
www.phys.ualberta.ca /~gingrich/phys395/notes/node15.html   (310 words)

  
 Living on Earth: Loop Current Powers Hurricanes   (Site not responding. Last check: 2007-10-20)
WALKER: Yeah, the Loop Current is actually part of the large scale clockwise gyre of the North Atlantic circulation.
And it flows very rapidly; the waters in the Loop Current and the Gulf Stream are the fastest flowing waters in the Atlantic Ocean.
Because the Loop Current is in the Gulf of Mexico probably 95 percent of the time.
www.loe.org /shows/segments.htm?programID=05-P13-00038&segmentID=1   (713 words)

  
 4QD-TEC: Current Loop Interface
This is a very simple circuit to interface a current loop sensor to an input which is designed for a voltage, such as that from a standard potentiometer.
The throttle itself consists of a coil and some electronics with a steel jacketed brass slug which is moved in and out of the coil by the throttle movement.
The assembly has only two contacts and draws a current of between 600 microamps and 2 milliamps: the current varies with slug position as the throttle is moved.
www.4qdtec.com /curli.html   (325 words)

  
 OMB-DBK5 : 4-Channel Current Output Card for OMB-DAQBOARD-2000 Series
The OMB-DBK5 acts as a current loop transmitter by modulating current from an external source.
Since the isolated outputs of the OMB-DBK5 are loop powered, the card maintains control of the loop current even when the data acquisition system is powered down.
When loop power is first applied, the OMB-DBK5’s outputs assume their 4 mA default state.
www.omega.co.uk /ppt/pptsc.asp?ref=OMB-DBK5   (286 words)

  
 4-20 mA current instrument loop equipment.
The display and the current generator both have resolutions of 0.05% which means that the current can be set and read in increments of 10 microamperes or better, far surpassing the resolution of most 4-20 mA transmitters and receivers.
The loop must be grounded in one place only, generally at the negative end of the receiver.
The Scan-Data ITI 4-20 mA current isolator is used to eliminate grounding errors in the loop.
www.psicompany.com /telemetry/instloop.htm   (617 words)

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