Comptus A70-DL0 User manual

1
INSTRUCTION MANUAL
for
WIND DIRECTION TRANSMITTER
MODELA70-DL0
DOCUMENT #1147 , Version K
Model A70-DL
__XX____ 360oRange ______ 540oRange
A75-302 Wind Vane Track Mounted Transmitter
®

2
INTRODUCTION
The A70 Wind Direction Transmitter monitors
winddirectionandproducesaelectricaloutput
signalproportional towinddirection(azimuth). The
windvaneisbalancedtoprevent“parking”should
themountingnotbelevel.Thesignalmaybemoni-
toredby a computer,instrumentation or displayed
ona meter.
The Transmitter converts the information from
the sensor to a 4-20 ma signal proportional to
wind direction.
An external source of excitation in the range of
12 - 24 VDC is required. Both operating power
and output signal are provided by the same wire
pair.
Two wind direction ranges, 0 - 360oand 0 -
540oare available. The 540orange is recom-
mended if a mechanical chart recorder will
record wind direction. This range reduces
transitions from zero to full scale when the wind
is from the North, preventing the entire chart
from being “painted.” The 360orange is recom-
mended when wind direction is electronically
recorded. The 360orange provides the best
resolution and the least cost. The 540orange is
best when abrupt transitions from zero to full
scale are undesirable.
Figure 1
Recorder Trace with Predominate
North Wind
540oScale 360oScale
..
. .
..
. .
. .
. .
. .
N E S W N E S N E S W N
Figure 2
Recorder Trace with Predominate
South Wind
540oScale 360oScale
. .
. .
. .
. .
. .
. .
. .
. .
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/60oC standard.
-20o/70oC 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:Transmittercircuit board 1 ounce
Connectors:
Barrier Strip to Accept Awg #14 or smaller wire
Accessories: A96 Lightning Arrestor
recommended for sensor protection
A70-LPDD
Loop Powered Digital Display

4
DESCRIPTION
The A75-302 Wind Vane is injection molded of
black ultraviolet stabilized Lexan. The wind
vane shaft is supported by two shielded stainless
steel precision ball bearings. All materials are
corrosion 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 precision
conductive plastic potentiometer located in the
main body. An analog voltage linearly propor-
tional to wind direction is produced when a
constant excitation voltage is applied to the
potentiometer.
The Transmitter converts the output voltage from
the wind vane, which is proportional to azimuth,
to a dc current. The current varies linearly from
4 ma at zero degrees azimuth to 20 ma at 360
degrees azimuth. The Transmitter provides a
regulated dc voltage for excitation of the wind
direction potentiometer.
The Transmitter is loop powered and protected
from damage by reverse polarity. All circuits are
protected 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 in
an existing enclosure. It may be supplied in a
steel NEMA 12 JIC box for inside deployment
orin a fiberglas or steelNEMA 4X boxwhen a
weatherproofbox is required.
Figure 3
Transmitter Component Layout
Figure4
WindVaneTerminals

5
Figure5
DirectionVane MountingDiagram

6
Figure6
Transmitter Connection Diagram

7
Figure7
MultipleTransmitterswithOnePowerSupply

8
INSTALLATION
Wiring Considerations
The wire type is noncritical for most applica-
tions. If the wiring is located in an electrically
noisyenvironment,orlongerthan60feet atwisted
pairwith shield is recommended. Connect the shield
togroundat one endonly,see Figure 6.Theinsula-
tionshouldbesunlightresistant.Polyethyleneor
polyvinylchlorideinsulationisrecommended.
Before proceeding verify that the maximum
resistance of the current loop including the
wiring and sensing element does not exceed the
maximum given by Formula 1. If this resistance
is exceeded the loop current will not attain full
scale.
Formula 1
Maximum Loop Resistance
R - Maximum Loop Resistance in Ohms
V - DC Excitation Voltage
R = (V - 10 Vdc) X 50
The resistance of various gages of copper wire is
given in Table 1.
Table 1
Wire Gage Resistance in
AWG Ohms per foot
12 .0016
14 .0026
16 .0041
18 .0065
20 .0103
22 .0165
24 .0262
A70-DL POWER SUPPLY
Proper operation of the Transmitter requires that
the power supply provide a voltage in the range
of 12-24 VDC. Voltage ripple must be less than
100 volts per second for proper operation. The
Transmitter is designed so that the loop current
will not exceed approximately 30 ma under any
circumstances.
A 12 volt power supply can drive a current loop
with a total resistance of 150 ohms. A 16 volt
power supply can drive a current loop with a
total resistance of 450 ohms.
Figure8
Graphof MaximumLoop Resistance
voltage
Excitation
Minimum
Excitation Voltage
10 14 18 22 26
300
100
0
200
Resistance
Total Loop
600
400
500
Ohms
A96-100P Surge Arrestor

9
Location
Do not install this equipment in the same enclo-
sure with a liquid electrolyte battery unless
ventilation is provided. Various gasses emitted
from the battery will cause both premature and
intermittent circuit failure.
Choose a protected mounting location for the
Transmitter enclosure. Attach it to a back plane
or other supporting structure. Special consider-
ation must be given to installations where the
sensors or electronics will be exposed to strong
radio frequency radiation or strong magnetic
fields. Contact the factory for applications
assistance.
The wind vane should be mounted at the point at
which it is desired to sample the wind. Typi-
cally, it is located as high as feasible and well
clear of obstructions.
Do not mount the wind vane directly above a
vertical wall as this location often has turbulent
air flow.
It may be mounted on an existing structure, on a
natural formation, or on a mast or tower. It is
desirable to mount the vane so that the support-
ing structure will not influence the wind charac-
teristics in its immediate vicinity. If the sensor
is mounted above a roof top or similar building
structure, it should be high enough so that the
wind deflected off the structure will not affect it,
typically 5 to 10 feet or more.
If mounted to the side of a supporting structure it
should be mounted at least ten structure diam-
eters away from the structure in order to take the
sensor out of the disturbed air around the struc-
ture. It should be mounted toward the prevailing
wind, and be positioned so that the influence of
structural members is minimized.
A preferred mounting which is commonly used
is a telescopic tower for installations up to forty
or fifty feet high; a tower commonly used for TV
antenna support, consisting of concentric pieces
oftubing approximatelytenfeetlong,guyedat each
section,issuitable. Abovethisheightself-supporting
orguyed lightweight structural towerscanbeused.
If the “S” mast is to be mounted on a metallic
tower consideration must be given to galvanic
corrosion which occurs between dissimilar
metals. Attachment to galvanized steel towers
using stainless steel hose clamps is acceptable.
For other combinations of metals recommended
practice is to electrically insulate the “S” mast
from the tower with a plastic bushing or sheet.
Alternatively fabricate a “S” mast from the same
material as the tower. This consideration is
especially important in locations exposed to salt
spray and air.
Lightning Protection
The Transmitter electronics has integral metal
oxide varistors for protection from lightning
induced surges, electrostatic discharge and other
atmospheric discharges. Wind blown aerosols
such as sand and snow can generate electrostatic
charges with consequences similar to lightning
discharges. The A96 Series of gas tube surge
arrestors can safely dissipate much higher energy
discharges than the internal varistors.
Aconsequenceoftherapid rise time of electrostatic
dischargesis theinductanceofthe grounding
systemandinterconnectingwiringisgenerallyof
moreconcernthan resistance. Gas tube surge
arrestorsshould be placedas close tothe device
theyare intended to protect to minimize the induc-
tanceinthewiring.
In highly exposed systems the sensors should be
protected by gas tube surge arrestors located as
closely as possible to them, typically 12 inches
or less. The Transmitter electronics can benefit
from another set of gas tube surge arrestors
located where the sensor wiring enters the
controlbuilding. Gas tubesurgearrestorsare
recomended for any system with underground
wiring.

10
Figure9
Poor WindSensorPlacement OverVerticalWall
Figure10
NorthAlignmentMark

11
Orientation
It is usually desirable to relate the wind direction
readings to True North. If a magnetic compass is
used the deviation from True North must be
determined. A topographical map contains this
information. For example if the deviation is 15
degrees West, a magnetic compass will indicate
15 degrees when pointed at True North. If the
deviation is East, then subtract it from 360 to
obtain the reading for True North.
Thehousing ofthe wind vanehasaNorth alignment
markmoldedintoit.RefertoFigure10.Thismust
beoriented sothat it istoward the North. The
vane’smounting holesareorientedsuchthatthe“S”
mast ison a North- South linewith respect tothe
vane.Forinstallationsusinglarge,climbabletowers
thevane may be oriented by pivoting the “S” mastin
thehoseclamps. Forsmaller towers pivot theentire
toweruntil the“S”mastisproperly aligned.
Do not press on the top of the vane as it may
damage the bearings. To install the wind vane,
grasp it about its lower body and press it with a
twisting motion onto the mast. Align the 1/8"
holes in the base of the wind vane with the holes
in the “S” mast. Secure the vane to the mast by
passingthe cotter pin through theholesandtighten-
ingthesetscrew.
Slide the protective boot over the base of the
wind vane after wiring is complete. Tape its
base to the mast to secure it in place.
Wiring
Connect the end of the cable with the spade lugs
to the sensor using a #4 nut driver. There are
three brass studs with 4-40 thread that extend
from the bottom of the wind vane housing.
Attach the sensor cable to these studs being
careful to tighten only the outer #4 hex nut to 3
inch-pounds torque. If the inner nut is loosened
or the nuts are tightened simultaneously the stud
may rotate. This may result in a poor electrical
connectioninsidethewindvane. SeeFigure9.
We recommend the system be assembled and
testedon thegroundbefore finalinstallation.
1. Select a suitable mounting location for the
Transmitter.
2. Mount the instrument to a wall or other
suitable panel using screws or bolts.
3. Refer to Figures 3 & 4. Connect the Redwire
ofthe signalcable to theDirectionVane Positive
“+” terminal.Tighten windvaneterminalto 3inch
pounds.
4. Connect the Green (or White) to the Direc-
tionVaneNegative“-” terminal.Tightenwind
vaneterminal to 3 inchpounds.
5. Connect the Black wire of the signal cable to
theDirectionVaneSignal center terminal.Tighten
windvane terminal to3inchpounds.
6. Connect the Red wire from the wind vane to
terminal #3 marked “WIND VANE +”.
7. Connect the Black lead from the wind vane to
the terminal #5 marked “WIND VANE SIG”.
8. Connect the Green (or White) lead from the
wind vane to terminal #4, the remaining wind
vane terminal.
9. Connect the Wind Direction current loop to
terminals 1 & 2 in the DIRECTION section
marked 4-20 ma. See Figures 5 & 6. Observe
polarityasmarked.
Shouldadditionalcable be requiredup to1000feet
maybecarefullysplicedintotheexistingcable.
Take care to preserve the color code. AWG #18 -
#22stranded copper wirewithshield is recom-
mended.
Secure the sensor cable to the supporting struc-
ture at intervals of four feet or less. If the cable
is allowed to vibrate in the wind a broken cable
may result.

12
OPERATION
Operation of the system is fully automatic and
commences when loop power is supplied.
The wind direction vane has a 8 degree dead
band centered about North. When in the dead
band the output signal will be at its minimum.
360 Degree Wind Direction Scale
The wind direction may be determined from the
output current with the use of Formula # 2
D - Wind Azimuth in Degrees
I - Loop Current in ma
D = (I - 4) X 360/16 Formula #2
Figure11
GraphofWindDirectionTransferFunction
360oRange
0 180 360
4
12
20
LoopCurrentinmA
Wind Azimuth
Degrees
N E S W N
540 Degree Wind Direction Scale
The wind direction may be determined from the
output current with the use of Formula # 3
D - Wind Azimuth in Degrees
I - Loop Current in ma
D = (I - 4) X 540/16 Formula 3
Figure12
GraphofWindDirectionTransferFunction
540oRange
N E S W N E S
0 180 360 540
LoopCurrentinmA
4
12
20
Wind Azimuth
Degrees
540 Degree Wind Range Conversion
To convert the 540 degree range to a 360 degree
range, subtract 360 degrees from any azimuth
greater than 360 degrees.

13
Voltage Across Sensing Resistor
I Loop Current in Milliamperes
R Resistance in Ohms
V Voltage in Volts
V = I X R / 1000 Formula 4
Figure13
CurrenttoVoltageTransferFunction
for 100 Ohm Resistor
0 4 8 12 16 20
0.4
1.2
2.0
Voltage
Loop Current
milliamperes
ICING
Under some conditions operation of the wind
vane will be degraded by the presence of ice.
This most often occurs as the result of freezing
rain. The condition quickly clears when sun-
shine heats the wind vane causing the ice to
melt. The condition may persist for hours or
days in the absence of bright sunshine. No
permanentdamageis done to thewind vane.

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MAINTENANCE
Transmitter
It is recommended that the Transmitter be
checked for calibration each year. Refer to
Calibration section for details.
CALIBRATION
The instrument is fully calibrated at the factory
before shipment. The following procedure is
provided should adjustment be necessary in the
future.
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 electronic
grade silicon rubber to prevent tampering by
unauthorized personnel.
1. Connecta jumperbetween terminals 4& 5 of
theterminalstripmarked“WINDVANE”. This
simulatesa signal corresponding to zero degrees of
azimuth.
2. Adjust the potentiometer marked “DIR.
ZERO” to produce a 4 ma loop current.
3. Connect a jumper between terminals 3 & 5
of the terminal strip marked “WIND VANE”.
This simulates a signal corresponding to 359
degrees 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 problem
locations be systematically eliminated until the
problem is found.
There are four basic questions to answer when
trouble shooting (Ref. #1):
1. Did it ever work right?
2. What are the symptoms that tell you it’s not
working right?
3. When did it start working badly or stop
working?
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 may
obtain. Be sure to write down anything unusual.
The response to question #3 should probably not
be 3:04 P.M.. A useful response might be, “Just
after an electrical storm.” or, “Just after it fell off
the shelf.”
Double check all the simple solutions to the
problem before searching for complex ones. If
the problem occurs right after installation, it
probably 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 equipment
doesn’t function verify that it has power and is
turned on.
Systems containing parts which can be quickly
interchanged are easy to trouble shoot. Swap
parts until the problem moves. The location has
then been narrowed to the part that caused the
problem to move.
Sometimes there are multiple problems. These
reveal themselves in layers much like peeling an
onion.
It often helps to explain the problem to another
person, even if that person is not knowledgeable
about the particular piece of equipment.
This does two things. First it requires you to
organize the situation so it can be explained to
another. Secondly, it may turn out that you are
so familiar with the situation that you have
overlooked the obvious. Another person unfa-
miliar with the equipment may be able to help.
If you are unable to solve the problem, put it
aside until the next day. Some new thoughts will
probably occur while working on another
project.
References
1. “Troubleshooting is More Effective with the
Right Philosophy”, Robert A. Pease, Electronic
Design News, January 5, 1989.

16
TROUBLESHOOTING
INCORRECT DIRECTION INDICATION
Check the response with wind vane orientations
of North, South, East and West. The Northern
orientation is produced when the vane is aligned
with 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 the
positive and negative excitation terminals are
interchanged.
If the output signal is active for only half of the
range, then the signal terminal and one of the
excitation terminals are interchanged.
If the output constantly indicates just West of
North, then the negative excitation connection is
open or the signal terminal is short circuited to
the positive excitation terminal.
If the output is constantly just East of North then
the positive excitation terminal is open or the
signal terminal is short-circuited to the negative
excitation terminal.
LoopCurrent 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 voltage
20 ma, otherwise Loop resistance too high
operatesproperly:
OutputJumpy:Input &outputcablesinterchanged

17
DIRECTIONVANETESTING
The potentiometer in the direction vane has a
nominal resistance of 10000 (10K) ohms.
With the signal cable to the direction vane
disconnected from the transmitter an ohm meter
may be used to measure approximately 10000
(10K) ohms resistance between the (+) & (-)
excitation terminals.
The resistance between the direction vane signal
lead and either of the excitation terminals should
be less than 10000 (10K) ohms.
If the resistance values differ radically from the
above then the vane or the signal cable likely
contains a fault.
The signal lead of the wind vane will indicate an
open circuit if the vane is positioned in the dead
band 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
LIMITEDWARRANTY
COMPTUS extendsthiswarrantytotheoriginal
consumeronly.Anyproductmanufacturedby
Comptusiswarranted against defect fora periodof
ONEYEAR beginningon the date ofpurchase by
theconsumerortwoyearsbeginning on the date of
purchasefromComptusbytheauthorizeddealer,
whicheverexpiressooner.
TO OBTAIN WARRANTY SERVICE, the
purchaser must contact Comptus and receive
return authorization. Such correspondence
shouldbe addressed to:Comptus, 202 Tamarack
Rd.,Thornton, N.H. 03285.Allwarrantyservice is
performedat the factory.Allincidentalexpenses,
includingshipment ofproductstoComptusbythe
purchaser,shallbethesole responsibility ofthe
purchaser.
WARRANTY SERVICE is at the sole discretion
of Comptus and free of charge for parts and
labor. Under the above terms, Comptus will
repair 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 altered
by anyone except Comptus or its authorized
service agencies;
c) the serial number has not been defaced,
removed, or otherwise changed;
d) the damage has not been caused by acts of
nature including windstorm and hail beyond
those specified as within the range of operating
conditions;
e) the damage has not been caused by shipping.
THISWARRANTYISINPLACE OFALL
OBLIGATIONS OR LIABILITIES ON THE
PART OF COMPTUS FOR DAMAGES. IT
DOES NOT APPLY TO ANY COMPONENT
OR EQUIPMENT RESOLD BY COMPTUS
IN ITS ORIGINAL CONDITION AS RE-
CEIVED BY COMPTUS FROM THE
MANUFACTURER OR DISTRIBUTOR,
AMONG THE DAMAGES EXCLUDED
FROM THIS WARRANTY ARE ANY INCI-
DENTAL OR CONSEQUENTIAL DAM-
AGES ARISING OUT OF OR IN CONNEC-
TION WITH THE PRODUCT IN ANY
WAY. Any implied warranties are limited in
duration to the duration of the written war-
ranty. No representative or person is autho-
rized to give any other warranty or assume
for Comptus any other liability in connection
with the sale of its products.
THISWARRANTYGIVESYOUSPECIFIC
LEGALRIGHTS,ANDYOU MAYALSO HAVE
OTHERRIGHTSWHICH VARYFROMSTATE
TO STATE. SOME STATES DO NOTALLOW
THE EXCLUSION OR LIMITATION OF INCI-
DENTALORCONSEQUENTIALDAMAGES
OR LIMITATIONS ON HOW LONGAN IM-
PLIEDWARRANTYLASTS, SOTHEABOVE
LIMITATIONSAND/OREXCLUSIONS MAY
NOTAPPLYTOYOU.This warrantycomplies
withtheMagnuson-MossConsumerWarrantyAct,
andcompletelyreplaces any warranty printed on
promotional material describing products of
Comptus Inc.
HOWTORETURN EQUIPMENTTO

19
COMPTUS
1. ContacttheComptusServiceDepartmentwith
themodelandserialnumberoftheunit. Be
preparedtoprovide the symptoms oftheproblem
asmany are solved without the needforreturning
theequipment. Havea person with firsthand
experienceofthetrouble on hand toprovide
specificinformation.
2. Comptuswill issueaReturnMaterialAuthori-
zationNumber(RMA#)ifrequired.Thiswill
ensurethefastestresponse and least costforall
parties.Pleasereferencethisnumberinallcorre-
spondence.Thisnumbershouldbeprintedonthe
shippingcontainer.
3. Includeadescriptionofthe service desired
withthereturnedequipment.Ifthe equipmentis
beingreturnedforrepair, please include a descrip-
tionof the problem.
4. Iftheequipment is packaged inaplasticcase,
wrapitinaluminumfoilorotherconductive
material.Thiswillprotectitfromstaticelectricity,
aswell as prevent thepackingmaterialfrom
jammingmechanicalparts,suchasswitches.
Otherwise,placetheequipmentinaplasticbag,
againto preventcontaminationbypackingmate-
rial.
Placethe equipmentinasuitableshippingcon-
tainerandfillwithpackingmaterial.Thereshould
beatleastone inch of packing materialbetween
theequipmentandtheshippingcontaineronall
sides.
5. EquipmentwillbereturnedC.O.D.to sender if
anychargesareincurred,unlessotherarrange-
mentsaremadeinadvance.
SHIPTHEEQUIPMENTTO:
Comptus
202 Tamarack Rd.
Thornton NH 03285 U.S.A.
Telephone: [phone]
Tax: 603 726-7502
Email: [email protected]
NOTE: Please be sure to include the RMA
Number, as described in Item 1, on the shipping
container.
WWW.COMPTUS.COM Phone: [phone] Fax: [phone]
®

20
WWW.COMPTUS.COM Phone: [phone] Fax: [phone]
®