INSTRUCTION MANUAL for WIND DIRECTION TRANSMITTER … Gas_Specialty_Sensors/PDFs...Jan 05, 1989  · Two wind direction ranges, 0 - 360 o and 0 - 540 o are available. The 540 o range

1

INSTRUCTION MANUALfor

WIND DIRECTION TRANSMITTERMODEL A70-DL0

DOCUMENT #1147 , Version K

Model A70-DL

__XX____ 360o Range ______ 540o Range

A75-302 Wind VaneTrack Mounted Transmitter

®

2

INTRODUCTION

The A70 Wind Direction Transmitter monitorswind direction and produces a electrical outputsignal proportional to wind direction (azimuth). Thewind vane is balanced to prevent “parking” shouldthe mounting not be level. The signal may be moni-tored by a computer, instrumentation or displayedon a meter.

The Transmitter converts the information fromthe sensor to a 4-20 ma signal proportional towind direction.An external source of excitation in the range of12 - 24 VDC is required. Both operating powerand output signal are provided by the same wirepair.

Two wind direction ranges, 0 - 360o and 0 -540o are available. The 540o range is recom-mended if a mechanical chart recorder willrecord wind direction. This range reducestransitions from zero to full scale when the windis from the North, preventing the entire chartfrom being “painted.” The 360o range is recom-mended when wind direction is electronicallyrecorded. The 360o range provides the bestresolution and the least cost. The 540o range isbest when abrupt transitions from zero to fullscale are undesirable.

Figure 1Recorder Trace with Predominate

North Wind

540o Scale 360o Scale. .

. .. . . .

. . . . . .

N E S W N E S N E S W N

Figure 2Recorder Trace with Predominate

South Wind

540o Scale 360o Scale. . . . . .

. . . . . . . . . .

N E S W N E S N E S W N

3

SPECIFICATIONS

Operating Power: 12 - 24 VDC 30 ma max.Supplied by current loop

Input Device: Potentiometric Wind Vane Comptus Model A75-302 Qualimetrics Model 2102 RM Young Wind Monitor

Output: 4-20 ma for 0-360 degrees 4-20 ma for 0-540 degrees

Accuracy: Electronics + 1% Sensor See Separate Specs.

Loop Resistance: (Excit. Voltage - 9) X 50 ohms Max.

Temperature Range: Electronics 0o/60o C standard. -20o/70o C extended. Sensor See Separate Specs.

Dimensions: NEMA 12 Box 3" W X 4.5" L X 11.5" D Track Mount 2.25"W X 6" L X 1.5" D

Weight: Transmitter circuit board 1 ounce

Connectors: Barrier Strip to Accept Awg #14 or smaller wire

Accessories: A96 Lightning Arrestor recommended for sensor protection

A70-LPDDLoop Powered Digital Display

4

DESCRIPTION

The A75-302 Wind Vane is injection molded ofblack ultraviolet stabilized Lexan. The windvane shaft is supported by two shielded stainlesssteel precision ball bearings. All materials arecorrosion resistant. The sensor mounts on a .50"diameter mast. The sensor is supplied with an S-shaped aluminum mast and 60 feet of cable.

The wind vane is directly coupled to a precisionconductive plastic potentiometer located in themain body. An analog voltage linearly propor-tional to wind direction is produced when aconstant excitation voltage is applied to thepotentiometer.

The Transmitter converts the output voltage fromthe wind vane, which is proportional to azimuth,to a dc current. The current varies linearly from4 ma at zero degrees azimuth to 20 ma at 360degrees azimuth. The Transmitter provides aregulated dc voltage for excitation of the winddirection potentiometer.

The Transmitter is loop powered and protectedfrom damage by reverse polarity. All circuits areprotected from damage by high voltage tran-sients such as lightning by metal oxide varistors.

The Translator may be in one of several pack-ages. It may be track mounted for installation inan existing enclosure. It may be supplied in asteel NEMA 12 JIC box for inside deploymentor in a fiberglas or steel NEMA 4X box when aweather proof box is required.

Figure 3Transmitter Component Layout

Figure 4Wind Vane Terminals

5

Figure 5Direction Vane Mounting Diagram

6

Figure 6Transmitter Connection Diagram

7

Figure 7Multiple Transmitters with One Power Supply

8

INSTALLATION

Wiring Considerations

The wire type is noncritical for most applica-tions. If the wiring is located in an electricallynoisy environment, or longer than 60 feet a twistedpair with shield is recommended. Connect the shieldto ground at one end only, see Figure 6. The insula-tion should be sunlight resistant. Polyethylene orpolyvinyl chloride insulation is recommended.

Before proceeding verify that the maximumresistance of the current loop including thewiring and sensing element does not exceed themaximum given by Formula 1. If this resistanceis exceeded the loop current will not attain fullscale.

Formula 1Maximum Loop Resistance

R - Maximum Loop Resistance in OhmsV - DC Excitation Voltage

R = (V - 10 Vdc) X 50

The resistance of various gages of copper wire isgiven in Table 1.

Table 1Wire Gage Resistance inAWG Ohms per foot12 .001614 .002616 .004118 .006520 .010322 .016524 .0262

A70-DL POWER SUPPLY

Proper operation of the Transmitter requires thatthe power supply provide a voltage in the rangeof 12-24 VDC. Voltage ripple must be less than100 volts per second for proper operation. TheTransmitter is designed so that the loop currentwill not exceed approximately 30 ma under anycircumstances.

A 12 volt power supply can drive a current loopwith a total resistance of 150 ohms. A 16 voltpower supply can drive a current loop with atotal resistance of 450 ohms.

Figure 8Graph of Maximum Loop Resistance

voltageExcitationMinimum

Excitation Voltage 10 14 18 22 26

300

100

0

200

ResistanceTotal Loop

600

400

500

Ohms

A96-100P Surge Arrestor

9

LocationDo not install this equipment in the same enclo-sure with a liquid electrolyte battery unlessventilation is provided. Various gasses emittedfrom the battery will cause both premature andintermittent circuit failure.

Choose a protected mounting location for theTransmitter enclosure. Attach it to a back planeor other supporting structure. Special consider-ation must be given to installations where thesensors or electronics will be exposed to strongradio frequency radiation or strong magneticfields. Contact the factory for applicationsassistance.

The wind vane should be mounted at the point atwhich it is desired to sample the wind. Typi-cally, it is located as high as feasible and wellclear of obstructions.

Do not mount the wind vane directly above avertical wall as this location often has turbulentair flow.

It may be mounted on an existing structure, on anatural formation, or on a mast or tower. It isdesirable to mount the vane so that the support-ing structure will not influence the wind charac-teristics in its immediate vicinity. If the sensoris mounted above a roof top or similar buildingstructure, it should be high enough so that thewind deflected off the structure will not affect it,typically 5 to 10 feet or more.

If mounted to the side of a supporting structure itshould be mounted at least ten structure diam-eters away from the structure in order to take thesensor out of the disturbed air around the struc-ture. It should be mounted toward the prevailingwind, and be positioned so that the influence ofstructural members is minimized.

A preferred mounting which is commonly usedis a telescopic tower for installations up to fortyor fifty feet high; a tower commonly used for TVantenna support, consisting of concentric pieces

of tubing approximately ten feet long, guyed at eachsection, is suitable. Above this height self-supportingor guyed lightweight structural towers can be used.

If the “S” mast is to be mounted on a metallictower consideration must be given to galvaniccorrosion which occurs between dissimilarmetals. Attachment to galvanized steel towersusing stainless steel hose clamps is acceptable.

For other combinations of metals recommendedpractice is to electrically insulate the “S” mastfrom the tower with a plastic bushing or sheet.Alternatively fabricate a “S” mast from the samematerial as the tower. This consideration isespecially important in locations exposed to saltspray and air.

Lightning Protection

The Transmitter electronics has integral metaloxide varistors for protection from lightninginduced surges, electrostatic discharge and otheratmospheric discharges. Wind blown aerosolssuch as sand and snow can generate electrostaticcharges with consequences similar to lightningdischarges. The A96 Series of gas tube surgearrestors can safely dissipate much higher energydischarges than the internal varistors.

A consequence of the rapid rise time of electrostaticdischarges is the inductance of the groundingsystem and interconnecting wiring is generally ofmore concern than resistance. Gas tube surgearrestors should be placed as close to the devicethey are intended to protect to minimize the induc-tance in the wiring.

In highly exposed systems the sensors should beprotected by gas tube surge arrestors located asclosely as possible to them, typically 12 inchesor less. The Transmitter electronics can benefitfrom another set of gas tube surge arrestorslocated where the sensor wiring enters thecontrol building. Gas tube surge arrestors arerecomended for any system with undergroundwiring.

10

Figure 9Poor Wind Sensor Placement Over Vertical Wall

Figure 10North Alignment Mark

11

Orientation

It is usually desirable to relate the wind directionreadings to True North. If a magnetic compass isused the deviation from True North must bedetermined. A topographical map contains thisinformation. For example if the deviation is 15degrees West, a magnetic compass will indicate15 degrees when pointed at True North. If thedeviation is East, then subtract it from 360 toobtain the reading for True North.

Thehousing of the wind vane has a North alignmentmark molded into it. Refer to Figure 10. This mustbe oriented so that it is toward the North. Thevane’s mounting holes are oriented such that the “S”mast is on a North - South line with respect to thevane. For installations using large, climbable towersthe vane may be oriented by pivoting the “S” mast inthe hose clamps. For smaller towers pivot the entiretower until the “S” mast is properly aligned.

Do not press on the top of the vane as it maydamage the bearings. To install the wind vane,grasp it about its lower body and press it with atwisting motion onto the mast. Align the 1/8"holes in the base of the wind vane with the holesin the “S” mast. Secure the vane to the mast bypassing the cotter pin through the holes and tighten-ing the set screw.

Slide the protective boot over the base of thewind vane after wiring is complete. Tape itsbase to the mast to secure it in place.

Wiring

Connect the end of the cable with the spade lugsto the sensor using a #4 nut driver. There arethree brass studs with 4-40 thread that extendfrom the bottom of the wind vane housing.Attach the sensor cable to these studs beingcareful to tighten only the outer #4 hex nut to 3inch-pounds torque. If the inner nut is loosenedor the nuts are tightened simultaneously the studmay rotate. This may result in a poor electricalconnection inside the wind vane. See Figure 9.

We recommend the system be assembled andtested on the ground before final installation.

1. Select a suitable mounting location for theTransmitter.

2. Mount the instrument to a wall or othersuitable panel using screws or bolts.

3. Refer to Figures 3 & 4. Connect the Red wireof the signal cable to the Direction Vane Positive“+” terminal. Tighten wind vane terminal to 3 inchpounds.

4. Connect the Green (or White) to the Direc-tion Vane Negative “-” terminal. Tighten windvane terminal to 3 inch pounds.

5. Connect the Black wire of the signal cable tothe Direction Vane Signal center terminal. Tightenwind vane terminal to 3 inch pounds.

6. Connect the Red wire from the wind vane toterminal #3 marked “WIND VANE +”.

7. Connect the Black lead from the wind vane tothe terminal #5 marked “WIND VANE SIG”.

8. Connect the Green (or White) lead from thewind vane to terminal #4, the remaining windvane terminal.

9. Connect the Wind Direction current loop toterminals 1 & 2 in the DIRECTION sectionmarked 4-20 ma. See Figures 5 & 6. Observepolarity as marked.

Should additional cable be required up to 1000 feetmay be carefully spliced into the existing cable.Take care to preserve the color code. AWG #18 -#22 stranded copper wire with shield is recom-mended.

Secure the sensor cable to the supporting struc-ture at intervals of four feet or less. If the cableis allowed to vibrate in the wind a broken cablemay result.

12

OPERATION

Operation of the system is fully automatic andcommences when loop power is supplied.

The wind direction vane has a 8 degree deadband centered about North. When in the deadband the output signal will be at its minimum.

360 Degree Wind Direction ScaleThe wind direction may be determined from theoutput current with the use of Formula # 2

D - Wind Azimuth in DegreesI - Loop Current in ma

D = (I - 4) X 360/16 Formula #2

Figure 11Graph of Wind Direction Transfer Function

360o Range

0 180 360

4

12

20

Loo

p C

urre

nt i n

mA

Wind Azimuth Degrees

N E S W N

540 Degree Wind Direction Scale

The wind direction may be determined from theoutput current with the use of Formula # 3

D - Wind Azimuth in DegreesI - Loop Current in ma

D = (I - 4) X 540/16 Formula 3

Figure 12Graph of Wind Direction Transfer Function

540o Range

N E S W N E S0 180 360 540

Loo

p C

urre

nt in

mA

4

12

20

Wind Azimuth Degrees

540 Degree Wind Range Conversion

To convert the 540 degree range to a 360 degreerange, subtract 360 degrees from any azimuthgreater than 360 degrees.

13

Voltage Across Sensing Resistor

I Loop Current in MilliamperesR Resistance in OhmsV Voltage in Volts

V = I X R / 1000 Formula 4

Figure 13Current to Voltage Transfer Function

for 100 Ohm Resistor

0 4 8 12 16 20

0.4

1.2

2.0

Vol

tage

Loop Currentmilliamperes

ICING

Under some conditions operation of the windvane will be degraded by the presence of ice.This most often occurs as the result of freezingrain. The condition quickly clears when sun-shine heats the wind vane causing the ice tomelt. The condition may persist for hours ordays in the absence of bright sunshine. Nopermanent damage is done to the wind vane .

14

MAINTENANCE

Transmitter

It is recommended that the Transmitter bechecked for calibration each year. Refer toCalibration section for details.

CALIBRATION

The instrument is fully calibrated at the factorybefore shipment. The following procedure isprovided should adjustment be necessary in thefuture.Gain & Zero Adjustments

Potentiometer R34 sets the wind direction zero.Potentiometer R40 sets the wind direction gain.

WIND DIRECTION TRANSMITTER

The adjustments may be sealed with electronicgrade silicon rubber to prevent tampering byunauthorized personnel.

1. Connect a jumper between terminals 4 & 5 ofthe terminal strip marked “WIND VANE”. Thissimulates a signal corresponding to zero degrees ofazimuth.

2. Adjust the potentiometer marked “DIR.ZERO” to produce a 4 ma loop current.

3. Connect a jumper between terminals 3 & 5of the terminal strip marked “WIND VANE”.This simulates a signal corresponding to 359degrees of azimuth.

4. Adjust the potentiometer marked “DIR.GAIN” to produce 20 ma of loop current.

15

Trouble Shooting Philosophy

Effective trouble shooting requires that problemlocations be systematically eliminated until theproblem is found.

There are four basic questions to answer whentrouble shooting (Ref. #1):

1. Did it ever work right?

2. What are the symptoms that tell you it’s notworking right?

3. When did it start working badly or stopworking?

4. What other symptoms showed up just before,just after, or at the same time as the failure?

It is best to write down any clues you mayobtain. Be sure to write down anything unusual.

The response to question #3 should probably notbe 3:04 P.M.. A useful response might be, “Justafter an electrical storm.” or, “Just after it fell offthe shelf.”

Double check all the simple solutions to theproblem before searching for complex ones. Ifthe problem occurs right after installation, itprobably has a simple solution.

If an automobile engine cranks, but doesn’t start,make sure there is fuel in the tank before replac-ing the engine. If the electronic equipmentdoesn’t function verify that it has power and isturned on.

Systems containing parts which can be quicklyinterchanged are easy to trouble shoot. Swapparts until the problem moves. The location hasthen been narrowed to the part that caused theproblem to move.

Sometimes there are multiple problems. Thesereveal themselves in layers much like peeling anonion.

It often helps to explain the problem to anotherperson, even if that person is not knowledgeableabout the particular piece of equipment.

This does two things. First it requires you toorganize the situation so it can be explained toanother. Secondly, it may turn out that you areso familiar with the situation that you haveoverlooked the obvious. Another person unfa-miliar with the equipment may be able to help.

If you are unable to solve the problem, put itaside until the next day. Some new thoughts willprobably occur while working on anotherproject.

References

1. “Troubleshooting is More Effective with theRight Philosophy”, Robert A. Pease, ElectronicDesign News, January 5, 1989.

16

TROUBLE SHOOTING

INCORRECT DIRECTION INDICATION

Check the response with wind vane orientationsof North, South, East and West. The Northernorientation is produced when the vane is alignedwith the mark on the edge of the housing.

If the output is correct for the Southern orienta-tion, but incorrect for East and West, then thepositive and negative excitation terminals areinterchanged.

If the output signal is active for only half of therange, then the signal terminal and one of theexcitation terminals are interchanged.

If the output constantly indicates just West ofNorth, then the negative excitation connection isopen or the signal terminal is short circuited tothe positive excitation terminal.

If the output is constantly just East of North thenthe positive excitation terminal is open or thesignal terminal is short-circuited to the negativeexcitation terminal.

Loop Current Failure Description

0 ma (constant): Current loop polarity re-versed Open circuit in cable Power supply failure

4 ma (constant): Open in Positive or Signal wire connecting wind vane to transmitter Wind vane potentiometer open

20 ma (constant): Open in Negative wire connecting wind vane to transmitter

Less than 4 ma: Low power supply voltage Loop resistance too high

Greater than 20: Short circuit in cable

Does Not Reach Low power supply voltage20 ma, otherwise Loop resistance too highoperates properly:

Output Jumpy: Input & output cables interchanged

17

DIRECTION VANE TESTING

The potentiometer in the direction vane has anominal resistance of 10000 (10K) ohms.

With the signal cable to the direction vanedisconnected from the transmitter an ohm metermay be used to measure approximately 10000(10K) ohms resistance between the (+) & (-)excitation terminals.

The resistance between the direction vane signallead and either of the excitation terminals shouldbe less than 10000 (10K) ohms.

If the resistance values differ radically from theabove then the vane or the signal cable likelycontains a fault.

The signal lead of the wind vane will indicate anopen circuit if the vane is positioned in the deadband which is centered about North.

DIRECTION VANE SIMULATION

The wind vane may be simulated using a potenti-ometer with a nominal resistance of 10000 (10K)ohms.

18

LIMITED WARRANTY

COMPTUS extends this warranty to the originalconsumer only. Any product manufactured byComptus is warranted against defect for a period ofONE YEAR beginning on the date of purchase bythe consumer or two years beginning on the date ofpurchase from Comptus by the authorized dealer,whichever expires sooner.

TO OBTAIN WARRANTY SERVICE, thepurchaser must contact Comptus and receivereturn authorization. Such correspondenceshould be addressed to: Comptus, 202 TamarackRd., Thornton, N.H. 03285. All warranty service isperformed at the factory. All incidental expenses,including shipment of products to Comptus by thepurchaser, shall be the sole responsibility of thepurchaser.WARRANTY SERVICE is at the sole discretionof Comptus and free of charge for parts andlabor. Under the above terms, Comptus willrepair or replace the defective component(s),provided that:

a) the product has not been subjected to abuse,neglect, accident, alteration, improper installa-tion or servicing, or used in violation of instruc-tions furnished by Comptus;

b) the product has not been repaired or alteredby anyone except Comptus or its authorizedservice agencies;

c) the serial number has not been defaced,removed, or otherwise changed;

d) the damage has not been caused by acts ofnature including windstorm and hail beyondthose specified as within the range of operatingconditions;

e) the damage has not been caused by shipping.

THIS WARRANTY IS IN PLACE OF ALLOBLIGATIONS OR LIABILITIES ON THEPART OF COMPTUS FOR DAMAGES. ITDOES NOT APPLY TO ANY COMPONENTOR EQUIPMENT RESOLD BY COMPTUSIN ITS ORIGINAL CONDITION AS RE-CEIVED BY COMPTUS FROM THEMANUFACTURER OR DISTRIBUTOR,AMONG THE DAMAGES EXCLUDEDFROM THIS WARRANTY ARE ANY INCI-DENTAL OR CONSEQUENTIAL DAM-AGES ARISING OUT OF OR IN CONNEC-TION WITH THE PRODUCT IN ANYWAY. Any implied warranties are limited induration to the duration of the written war-ranty. No representative or person is autho-rized to give any other warranty or assumefor Comptus any other liability in connectionwith the sale of its products.THIS WARRANTY GIVES YOU SPECIFICLEGAL RIGHTS, AND YOU MAY ALSO HAVEOTHER RIGHTS WHICH VARY FROM STATETO STATE. SOME STATES DO NOT ALLOWTHE EXCLUSION OR LIMITATION OF INCI-DENTAL OR CONSEQUENTIAL DAMAGESOR LIMITATIONS ON HOW LONG AN IM-PLIED WARRANTY LASTS, SO THE ABOVELIMITATIONS AND/OR EXCLUSIONS MAYNOT APPLY TO YOU. This warranty complieswith the Magnuson-Moss Consumer Warranty Act,and completely replaces any warranty printed onpromotional material describing products ofComptus Inc.HOW TO RETURN EQUIPMENT TO

19

COMPTUS

1. Contact the Comptus Service Department withthe model and serial number of the unit. Beprepared to provide the symptoms of the problemas many are solved without the need for returningthe equipment. Have a person with firsthandexperience of the trouble on hand to providespecific information.

2. Comptus will issue a Return Material Authori-zation Number (RMA #) if required. This willensure the fastest response and least cost for allparties. Please reference this number in all corre-spondence. This number should be printed on theshipping container.

3. Include a description of the service desiredwith the returned equipment. If the equipment isbeing returned for repair, please include a descrip-tion of the problem.

4. If the equipment is packaged in a plastic case,wrap it in aluminum foil or other conductivematerial. This will protect it from static electricity,as well as prevent the packing material fromjamming mechanical parts, such as switches.

Otherwise, place the equipment in a plastic bag,again to prevent contamination by packing mate-rial.

Place the equipment in a suitable shipping con-tainer and fill with packing material. There shouldbe at least one inch of packing material betweenthe equipment and the shipping container on allsides.

5. Equipment will be returned C.O.D. to sender ifany charges are incurred, unless other arrange-ments are made in advance.

SHIP THE EQUIPMENT TO:

Comptus202 Tamarack Rd.Thornton NH 03285 U.S.A.

Telephone: 603 726-7500Tax: 603 726-7502Email: [email protected]

NOTE: Please be sure to include the RMANumber, as described in Item 1, on the shippingcontainer.

WWW.COMPTUS.COM Phone: 603 726-7500 Fax: 603 726-7502

®

20WWW.COMPTUS.COM Phone: 603 726-7500 Fax: 603 726-7502

®

21

Model A70-DLComponent Packing List

Quantity Description Quantity Received

1 A70-DL Translator _______

1 Direction Vane _______

1 S Mast _______

1 60 ft., 3 Cond. Cable _______

1 Protective boot _______

1 Instruction Manual _______

2 Hose Clamps _______

1 Certificate of Calibration _______

IMPORTANT: Please check your order on receipt to be certain all listed accessories are includedbefore discarding shipping container or packing material. All shortages must be reported within 10days of receipt.

WWW.COMPTUS.COM Phone: 603 726-7500 Fax: 603 726-7502

®

22WWW.COMPTUS.COM Phone: 603 726-7500 Fax: 603 726-7502

®