Model 6495 Freezing Rain Sensor User`s Manual
Contents
1. ECN DESCRIPTION DATE APPROVED A 5019 INITIAL RELEASE 4 2004 PK N MARK LABEI EM 4 P N M434026 WITH 4917027 AND CURRENT ECO AND REV LEVEL ATTACH TO CABLE ASSEMBLY WHERE SHOWN 2X a Em ee Uus Md 300 25 re 42 0 IN 6 FI 200 IN x ES BLK AN WHT V 6 GRN 1 APPEND THE FOLLOWING UNLESS OTHERWISE SPECIFIED RAWN BY TITLE DOCUMENTS WHEN CHANGING PK 4 6 04 L 8 THIS DOCUMENT aspe EEN 1 2 EVISED BY CABI ASS M BI pe XXX r 005 FRACTIONS 02 a DO NOT SCALE DRAWING im E N D R Al N MATL HECKED BY z allweatherinc EXCEPT AS MAY OTHERWISE BE SPECIFIED BY CONTRACT SEE BILL OF MATERIALS OWER AWOS THIS DOCUMENT AND THE DATA DISCLOSED HEREIN FINISH AN ENGINEER SE ENE AND HEREWITH IS NOT TO BE USED REPRODUCED OR AS ISSUED DISCLOSED IN WHOLE OR IN PART TO ANYONE WITHOUT NERONE AQ 1 A E THE WRITTEN PERMISSION OF ALL WEATHER INC APPROVALS DATE SME NONE RELEASE DATE SHEET 1 OF 1 allweatherinc All Weather Inc 1165 National Drive Sacramento CA 95818 Fax 916 928 1165 Phone 916 928 1000 Toll Free 800 824 5873 www allweatherinc com 6495 001 Rev C ECO 1526 August 20082. P Status P F D P Pass F Fail D Deice S Status Descriptor Okay blank 1 Probe Failure 2 Deicing Failure 3 Electronics Failure 40000 Calibration frequency Field Calibration F5 Page 6 Installation Installation Mechanical Mounting Power and Data Connections Model 6495 Freezing Rain Sensor User s Manual Mounting Bolts Access from back of sensor Mounting Plate Figure 2 Freezing Rain Sensor Mounting The Freezing Rain Sensor comes pre installed on a flat mounting plate which in turn attaches to a standard 2 pipe using U bolts l 2 3 4 Power Set the sensor into position on the mounting pole approximately 5 above ground level Install one U bolt from the back pole side of the mounting plate so that the pole sits in the U Feed the bolt ends through the plate s top two mounting holes and fasten with flat washers lock washers and Install the second U bolt through the bottom two mounting holes and fasten with flat washers lock washers and nuts Tighten all hardware The sensor utilizes 115vac 103 5 to 126 5 vrms 55 to 65 hertz input power The power cable connects to a standard three prong ac receptacle Normal operation continues for power interruptions of less than 10 milliseconds Power interruptions greater than 10 milliseconds cause the sensor to go into a reset condition Under this condition the sensor resumes op
3. for wear and damage repair or replace as needed 2 Visually inspect surface of probe for contaminants such as dirt oil fingerprints etc 3 Ifany contaminants are present clean probe using isopropyl alcohol and soft cotton cloth WARNING Freezing rain sensor probe assembly will be hot if sensor recently completed a deice cycle Ensure that probe assembly has cooled before cleaning probe While in the deice mode the probe will radiate a significant amount of heat This can be observed by placing hand close to but not on the sensor probe Always avoid direct contact of the probe with skin to avoid burn potential hazard CAUTION Do not touch the probe with bare hands as oil residue from skin will affect the performance of the sensor Annual Maintenance During quarterly maintenance of the 6495 Freezing Rain Sensor perform the following 1 Inspect all mounting hardware and cable assemblies for wear and damage repair or replace as needed 2 Clean probe using isopropyl alcohol and soft cotton cloth observing the warnings detailed above Page 11 Model 6495 Freezing Rain Sensor User s Manual Troubleshooting SYMPTOM POSSIBLE CAUSES ACTION Freezing rain data missing or Loose cable or connector Check all cables and F displayed for sensor connectors Repair or status replace if necessary No power to freezing rain sensor Check main power to the sensor is ON Freezing Rain Sensor software l
4. heaters deice the strut During deicing the maximum power drain is 400 watts The deicing system is capable of completely melting approximately 3 8mm of ice on the strut and probe within 30 seconds at 20 C Heat Sink The heat sink consists of a 4 5 pound 2 05 kilograms mass of anodized 6061 aluminum that separates the electronics and probe strut The heat sink provides heat dissipation for the probe and strut during deicing The purpose of the heat sink is to achieve a recovery time defined as the time required for the sensor to revert to ambient temperature after being deiced The heat sink thermally isolates the sensing element from the electronics heat which allows accurate measurement at temperatures at or close to 0 C Microcontroller The sensor uses an M80C51FB 8 bit microcontroller This chip contains an internal RS 232 interface The unit s firmware is contained on a separate ultraviolet erasable programmable read only memory UVEPROM chip mounted on a socket This permits the unit s software to be easily changed in the field by removing the UVEPROM chip from its socket and replacing it with a chip containing the new program An electrically erasable programmable read only memory EEPROM is used to store data and tables used in computation The unit also features a nonvolatile read and write memory RAM chip that permits any detected failure codes to be stored in the unit A failed unit can be brought back to a repair facility a
5. 019 INITIAL RELEASE 4 2004 PK B 1526 ADD ITEM 25 GROUND LUG TO TRAVEL W UNIT 8 15 08 BRG AO REF 2 AQT A TOP SE VIEW NUT INCLUDED WITH U BOLT REF xao 4 L aD aD E d 0 POLE REF EXISTING BOTTOM VIEW SCALE 1 2 APPEND THE FOLLOWING UNLESS OTHERWISE SPECIFIED DRAWN BY TITLE DOCUMENTS WHEN CHANGING E NE tai PK 4 06 04 o HEE A cos me EISE BY ASSEMBLY DRAWING e E 2 GALARPE 8 15 08 DO NOT SCALE DRAWING KEES F R rr IN G R Al N MATE allweatherinc SEE BILL OF MATERIALS SE SOR AWOS DESIGN ENGINEER FINISH SIZE DWG NO ASUESIEO PROJECT MANAGER 6 4 0 5 5 TREATMENT APPROVALS DATE SCALE 1 A RELEASE DATE SHEET 10F 1 ECIFIED SULAT DUCTO SHEATH 134026 ATTACH TO ON RS ENDS TIN ONLY F SHRINK TUBING IT M491740 AND CURRENT ECO NUMB LA em 4 ASSEMBLY WHERE SHOWN REVISIONS MO NO M491 740 003 REV ECN DESCRIPTION DAT
6. E APPROVED 5019 INTIAL RELEASE 4 2004 PK AN CA 4 M491740 DM e 25 e 25 E dt RED TX WHT RX BLK GND EXCEPT AS MAY OTHERWISE BE SPECIFIED BY CONTRACT THIS DOCUMENT AND THE DATA DISCLOSED HEREIN AND HEREWITH IS NOT TO DISCLOSED IN WHOLE OR THE WRITTEN PERMISSION 0 BE USED REPRODUCED OR PART TO ANYONE WITHOUT F ALL WEATHER INC APPEND THE FOLLOWING UNLESS OTHERWISE SPECIFIED DRAWN BY DOCUMENTS WHEN CHANGING eae PK 4 06 04 THIS DOCUMENT XX 010 ANGLES 1 2 REVISED BY CABI ASS BI Y 6 XXX 005 FRACTIONS 02 DO NOT SCALE DRAWING R ESE IN G RAI N MATL CHECKED BY ATA AWOS DH SEE BILL OF MATERIALS 7 allweatherinc FINISH DESIGN ENGINEER YEN AS ISSUED PROJECT MANAGER TREATMENT APPROVALS NONE RELEASE DATE M491 40 004 SHEET 1 1 DWG NO E REVISIONS M491741 003 NOTES UNLESS OTHERWISE SPECIFIED REV
7. Model 6495 Freezing Rain Sensor User s Manual allweatherinc All Weather Inc 1165 National Drive Sacramento CA 95834 USA 800 824 5873 www allweatherinc com Model 6495 Freezing Rain Sensor User s Manual Contents Technical SBecITICallOTiS E 1 Thi ory OF Opera or eter cett eret ni dre tre ia 2 Generali stc xt sere NIE EI C irc DM E ret et SML LR 2 F nctioral t ti ede hr tart iet eate e dte E 3 DISCO NR 3 5 Installation a A A EE 7 E A mM Mode Ee 7 Mechanical eelere 7 Power and Dala Connections uo et em Abs 7 7 7 8 nte Sm 9 MI 10 Standard ATI Te EE 10 ANOS Maintenance eee teen fete tu tee e nente te ee bris 11 usc tete eerte A ctu elus Nestea 11 Quartery Maintenant d o nod o gun a eae aaa se d ere due A OU ad 11 Ann alMaintenatnce came tada id 11 Troubleshooting 12 BICI Is ee E 14 Page iii Technical Specifications Output Range Output Format Input Power Power Consumption Size Weight Model 6495 Freezing Rain Sensor User s Manual Mass equivalent between 0 020 and 0 10 inches 0 5 mm and 2 5 mm RS 232 9600 2400 300 baud 115 vac 55 65 Hz 5 Watts in ice sensing mode 350 Watts in deicing mode 19 Hx 19 Wx 4 D 16 lbs 7 25 kg Page 1 Model 6495 Freezing Rain Sensor User s Manual Theory of Operation General Page 2 The AWI Model 6495 Freezing Rain Sensor uses an ult
8. cleaned if necessary every 90 days Clean the probe only when it is contaminated with foreign material such as dirt oil fingerprints etc Tools and Equipment Required e Soft cotton cloth lint free e Isopropyl alcohol WARNING Freezing rain sensor probe assembly will be hot if sensor recently completed a deice cycle Ensure that probe assembly has cooled before cleaning probe While in the deice mode the probe will radiate a significant amount of heat This can be observed by placing hand close to but not on the sensor probe Always avoid direct contact of the probe with skin to avoid burn potential hazard CAUTION Do not touch the probe with bare hands as oil residue from skin will affect the performance of the sensor 1 Inspect all mounting hardware and cable assemblies for wear and damage 2 Visually inspect surface of probe for contaminants such as dirt oil fingerprints etc 3 If any contaminants are present clean probe using isopropyl alcohol and soft cotton cloth AWOS Maintenance Model 6495 Freezing Rain Sensor User s Manual Monthly Maintenance During monthly maintenance of the 6495 Freezing Rain Sensor perform the following 1 Inspect all mounting hardware and cable assemblies for wear and damage repair or replace as needed Quarterly Maintenance During quarterly maintenance of the 6495 Freezing Rain Sensor perform the following 1 Inspect all mounting hardware and cable assemblies
9. e with the laws of classical mechanics A 0 02 inch 0 5mm thickness of ice on the probe causes the operating frequency of the probe to decrease by approximately 133 hertz The ice detector control circuitry utilizes a microprocessor to monitor probe frequency when instructed by the CDP The ice detector deices itself through internal heating elements in both the strut and probe After the ice detector is deiced the sensing probe cools quickly and is ready to sense ice formation again Electronics Housing ALL DIMENSIONS IN INCHES Figure 1 Freezing Rain Sensor Components Page 3 Model 6495 Freezing Rain Sensor User s Manual Page 4 Probe Assembly The probe assembly consists of the probe sensing element the strut and the deice collar The strut contains pickup and drive coils cartridge heaters a magnet and a retaining spring The probe assembly minimizes the flat area around the probe and contains radial grooves machined in the conical portion of the strut This design prevents water droplets from collecting around the probe nodal area in still air conditions The deice collar aids in breaking up ice that may form on the heat sink The sensor water shedding ability eliminates false signals due to water refreezing at the base when the atmosphere does not contain liquid water to actually form ice on the probe element Heaters Deicing is accomplished using a heater brazed in the interior of the probe A pair of cartridge
10. eration automatically after power is reapplied and the power up test sequence completes The internal power connections are shown below Terminals 1 and 2 and terminals 4 and 5 are on separate circuit breakers Page 7 Model 6495 Freezing Rain Sensor User s Manual Terminal Function 1 115 vac hot electronics 2 115 vac neutral electronics 3 Chassis ground model 0872C2 only 4 115 vac hot heater 5 115 vac neutral heater EI Chassis ground model 0872C3 only Dala The freezing rain sensor communicates with the DCP via an RS 232 interface daughter board mounted to the main PCB The data cable from the sensor is unterminated at the DCP end and connects to the RS 232 interface board at screw terminals on terminal block TB1 as shown in Figure 3 TB1 1 RS 232 TX 3 RS 232 GND M404806 5 RS 485 SERIAL FREEZING 2 RS 232 RX M491740 g RAIN 4 RS 485 1 SENSOR 6 GND Figure 3 DCP Data Connections Page8 Model 6495 Freezing Rain Sensor User s Manual Operation The Freezing Rain Sensor operates automatically receiving commands from and sending data packets to the DCP There are no controls or indicators on the sensor nor is there an internal power switch Page 9 Model 6495 Freezing Rain Sensor User s Manual Maintenance Standard Maintenance Page 10 Periodic maintenance should include the following The freezing rain sensor should be inspected and the probe
11. g of the probe which would have an adverse effect on freezing rain detection especially around 0 C ambient air temperature There is a feedback circuit to the microcontroller to ensure that the relay is operating properly The Freezing Rain Sensor communicates with the DCP via an RS 232 interface It transmits a data packet once per minute to the DCP The data packet contains the current probe frequency along with sensor status The CDP determines current freezing rain conditions using the reported frequency and the AWOS freezing rain algorithm Table 1 shows the commands sent by the DCP and the corresponding response from the sensor When a sensor failure is detected it is reported on the CDP main and diagnostic screens and is recorded in the maintenance log Page 5 Model 6495 Freezing Rain Sensor User s Manual Table 1 Freezing Rain Sensor Commands and Responses Command Description Command Response ZPS40000 Z Sensor ID P Status P F D P Pass F Fail D Deice S Status Descriptor Okay blank 1 Probe Failure 2 Deicing Failure 3 Electronics Failure 40000 frequency in Hz Send Routine Data Z1 Z3XX Perform Deice Cycle XX 60 ZDOK secs ZF2 Z Sensor ID F Status P F D P Pass F Fail Perform Extended Diagnostics Z4 D Deice 2 Status Descriptor Okay blank 1 Probe Failure 2 Deicing Failure 3 Electronics ZPS40000 Z Sensor ID
12. n is less than 0 002 in 15 minutes A system event is reported from the AWOS only after combining the sensor s output with data from the AWOS present weather sensor and temperature sensor Functional Description Model 6495 Freezing Rain Sensor User s Manual The Freezing Rain Sensor uses an ultrasonic axially vibrating probe to detect the presence of icing conditions This sensing probe is a nickel alloy tube mounted in the strut at its midpoint with 1 inch 25 4mm exposed to the atmosphere This tube exhibits magnetostrictive properties and expands and relaxes under the influence of a variable magnetic field A magnetic bias field is provided by a magnet mounted inside the strut and modulated by a drive coil surrounding the lower half of the tube A magnetostrictive oscillator MSO circuit is created by the addition of a pickup coil and operational amplifier The ultrasonic axial movement of the tube resulting from the activation of the drive coil causes a current to be induced in the pickup coil The current from the pickup coil drives the operational amplifier which provides the signal for the drive coil The oscillation frequency of the circuit is determined by the natural resonant frequency of the sensor tube which is tuned to approximately 40 000 hertz As the ice detector encounters an icing environment ice collects on the sensing probe The added mass of accreted ice causes the frequency of the sensing probe to decrease in accordanc
13. nd the failure code read to determine how the unit failed Watchdog Timer Reset Power Monitor A single chip combines the function of watchdog timer and power monitor The purpose of the watchdog timer is to monitor the operation of the microcontroller The microcontroller must output a pulse into the watchdog timer approximately every second or the watchdog timer causes the microcontroller to go into a reset condition which reinitializes the microcontroller The power monitor Communication Model 6495 Freezing Rain Sensor User s Manual circuit causes the microcontroller to reset any time that the voltage drops below 4 65 vdc which is the lower operational voltage for the memory circuits Any time that the voltage drops below 4 25 vdc it is possible for the memory circuits to lose memory The power monitor maintains the microcontroller in a reset condition until the supply voltage is above 4 65 vdc Heater Control The heater control circuit consists of a mechanical relay with a solid state interface circuit to the microcontroller When ice has accreted on the probe to a predetermined thickness typically 2 0mm the CDP instructs the heater circuit to furnish 115 vac to the heaters in the probe and strut causing the ice to melt A mechanical relay is used instead of a solid state relay to avoid any leakage current that might flow through the heater circuit when the relay is in a de energized state A leakage current would cause some heatin
14. ocked up Cycle power to sensor If no recovery cycle power to the FDCU If no recovery replace sensor Freezing Rain Sensor has failed Consult the SYSLOG for errors prior to the sensor going missing to confirm faulty operation before failure Replace sensor if necessary Freezing rain data Loose cables or connectors intermittent Check all cables and connectors Repair or replace if necessary Freezing Rain Sensor is faulty Consult the SYSLOG for errors and examine the freezing rain status word for possible causes of the problem Replace sensor if necessary Freezing Rain data inaccurate Freezing Rain Sensor requires maintenance Perform complete maintenance Freezing Rain Sensor has operational errors Cycle power to sensor If no recovery cycle power to the FDCU If no recovery replace sensor Freezing Rain Sensor software has locked up Cycle power to sensor If data still inaccurate replace sensor Probe frequency incorrect Check the probe frequency from the FDCU LCD display If out of tolerance replace the sensor Page 12 Model 6495 Freezing Rain Sensor User s Manual SYMPTOM POSSIBLE CAUSES ACTION Ice fails to melt from probe Freezing rain heater or processor has failed or software has locked up Cycle power to sensor If ice still fails to melt replace sensor Page 13 Model 6495 Freezing Rain Sensor U
15. rasonically vibrating probe to detect the presence of icing conditions The vibrating frequency of the probe nominally 40 000 hertz decreases with the accumulation of ice frost or wet snow After ice has accumulated on the probe to a predetermined thickness the AWOS DCP instructs the sensor to turn on its internal heaters to deice the probe During deicing maximum heater power is 400 watts The deicing system is capable of completely melting approximately 3 8 mm of ice on the probe and strut within 30 seconds at 20 degrees Celsius C The heat sink dissipates the heat from the probe assembly following a deice cycle The heat sink provides a recovery time 1 e the time required for the sensor to revert to ambient temperature of 10 minutes following a deice cycle The heat sink also thermally isolates the probe assembly from the electronics which allows accurate measurement at temperatures at or close to 0 C 32 F Frequency values and status are reported to the AWOS once each minute The system combines information from the freezing rain sensor with data from other AWOS sensors to generate the required reports of freezing rain A sensor event begins or continues following a de icing when the vibration frequency indicates 0 005 inches of ice accretion and the rate of frequency decrease exceeds 0 002 inches in 15 minutes The event ends whenever the frequency indicates less than 0 005 of ice or whenever the rate of ice accretio
16. ser s Manual Drawings The following pages contain drawings to help in the installation use and maintenance of this instrument Page 14 IQ m i J2 SEE DETAIL B EXCEPT AS MAY OTHERWISE BE SPECIFIED BY CONTRACT THIS DOCUMENT AND THE DATA DISCLOSED HEREIN AND HEREWITH IS NOT TO BE USED REPRODUCED OR DISCLOSED IN WHOLE OR IN PART TO ANYONE WITHOUT THE WRITTEN PERMISSION OF ALL WEATHER INC SEE DETAIL B SEE DETAIL C EM 25 GROUND LUG NOT SHOWN OTES UNLESS OTHERWISE SPECIFIED ZN remove OPTICAL CONVERTOR ASSEMBLY AND DISCARD A ARK LABEL ITEM 9 WITH MODEL 6495 ECO NUMBER REVISI N LEVEL AND SERIAL NUMBER PLACE ON SIDE OF UNIT AS SHOWN AAN spur CABLE BUSHING ITE 5 TO ALLOW SERTION OF POWER AND SIG AL CABLE ASSEMBLIES A Bac ITE 3 TEM Q9 mem 11 IT TO TRAVEL WITH UNIT 4X REVISIONS DWE NO 6495003 REV ECO DESCRIPTION DATE APPROVED 5
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