Biral SWS Series Operation And Maintenance Manual
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Biral SWS Series Operation And Maintenance Manual

Biral SWS Series Operation And Maintenance Manual

Present weather sensors
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SWS-050
SWS-100
SWS-200
SWS-250
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  • Page 1 SWS-050 SWS-100 SWS-200 SWS-250...
  • Page 3 The information contained in this manual (including all illustrations, drawings, schematics and parts lists) is proprietary to BIRAL. It is provided for the sole purpose of aiding the buyer or user in operating and maintaining the instrument. This information is not to be used for the manufacture or sale of similar items without written permission.

  • Page 4: Table Of Contents

    The sensors covered in this manual ................iv Features of the SWS sensors ..................v Customer satisfaction and After Sales Support ............vi Contacting Biral ....................... vi Two year warranty ....................vii If you need to return the sensor ................vii CE Certification –...
  • Page 5 Table 2-3 SWS-250 Operating data message format ..........38 Table 2-4 METAR Codes ..................40 Table 2-5 Message Extension for ALS-2 ..............41 Table 3-1 Commands for SWS series sensors ............44 Table 3-2 Command R? Response ................45 Table 3-3 Command T? Response ................46 Table 3-4 Sensor Responses ..................

  • Page 6: The Sensors Covered In This Manual

    General Information The sensors covered in this manual : Sensor Model Capability SWS-050 Visibility Obstruction to Vision SWS-100 Visibility Precipitation type identification 1 Fault relay switch 1 Relay for visibility 1 Relay for precipitation or visibility SWS-200 Visibility Precipitation type identification 1 Fault relay switch 1 Relay for visibility 1 Relay for precipitation or visibility...

  • Page 7: Features Of The Sws Sensors

    There are currently four sensors in the SWS sensor range. These are the SWS-050, the SW- 100, the SW-200 and the SWS-250. Any of these can be supplied to be used with the Biral Ambient Light Sensor, model ALS-2. Throughout this manual the term SWS Sensor is used...

  • Page 8: Contacting Biral

    Customer Satisfaction At Biral we set our standards high and only your complete satisfaction is acceptable to us. If you believe your experience has not met these standards we would be grateful if you would contact us so we can rectify any issues you may have (equally, if you have any positive experiences you would like to share).

  • Page 9: Two Year Warranty

    The customer is responsible for the shipping costs. CE Certification - Safety All Biral’s SWS sensors comply with the requirements for CE marking. Once installed, it is the user’s responsibility to ensure that all connections made to the sensor comply with all...

  • Page 11: Sensor Set-Up

    Section 1 Sensor Set-up SENSOR SET-UP The format of this section is such that it logically follows these recommended procedural steps: Step 1 - Unpack equipment and ensure that all required parts are supplied and identified. Step 2 - Make electrical connection as required for testing and configuration. Step 3 - Power up and test equipment on bench.

  • Page 12: Step 1 - Unpacking The Sensor

    Sensor Set-up Section 1 1.1 STEP 1 - Unpacking the sensor The sensor is packed in a foam filled shipping container and is fully assembled ready for use. The sensor is delivered with: U-bolts for pole mounting SWS sensor in 2 off ferrites for cable foam-filled EMC protection...

  • Page 13: Step 2 - Electrical Connections

    Section 1 Sensor set-up 1.2 STEP 2 - Electrical Connections ALL ELECTRICAL CONNECTIONS SHOULD BE COMPLETED BEFORE APPLYING POWER TO THE SENSOR 1.2.1 Cables Unless purchased as an option the sensor is not supplied with power and data cables. For the power and data cables we recommend you use screened, twisted pair cables in a suitable outdoor EMC and UV resistant sheath (this is particularly important for the data cables).

  • Page 14: Figure 1-3 Power And Signal Connections

    Sensor Set-up Section 1 To assist in this four cable glands are provided (see Figure 1-2): - the 2 small cable glands are for cables between 3.5 to 7.00mm diameter - the 2 larger glands are for cable between 4.5 to 10mm diameter Any or all of these glands can be used.

  • Page 15: Table 1-1 Pin Connections For Power Supply

    Section 1 Sensor set-up For ease of assembly it is recommended that 24AWG stranded (7/32) or solid wires are used, or equivalent. These are ideal for the low power requirements of the system. However the connectors can accommodate wires from 20AWG down to 26AWG (0.5 to 0.13 mm ), of solid or stranded construction.

  • Page 16: Figure 1-4 Location Of J7, Rs232/422/485 Select

    Sensor Set-up Section 1 Pin Connections for RS232 or RS422/RS485 Signal Interfaces The sensors can be operated with either RS232 OR RS422 OR RS485 communications. It is not possible to operate both the RS232 and the RS422/RS485 together. If there is to be a long distance between the sensor and its control computer (more than 40 metres), then the RS422 or RS485 configuration should be used and a RS422 communications port installed in the control computer.

  • Page 17: Figure 1-5 Relay Connections. Relay Contacts Are Rated 2A, 250V Ac

    Section 1 Sensor set-up 1.2.4 Connecting the relays The unique ability to switch equipment using a visibility (fog) relay and /or a precipitation (rain, snow) relay is a feature of the SWS-100 and SWS-200 sensors. For example you can set relays to automatically switch a speed reduction sign when visibility is below 100 m and then switch an additional ‘danger of aquaplaning’...

  • Page 18: Table 1-4 Connections For 0-10 V Analogue Output

    Sensor Set-up Section 1 1.2.5 Pin connections for 0-10 V analogue output An analogue output representing Meteorological Optical Range (MOR) as a signal between 0 and 10 V is standard on the SWS-100 and SWS-200 sensors. The connections are as follows, Table 1-4. Pin Number Designation J12/H...

  • Page 19: Figure 1-6 Als-2 Connecting System

    Section 1 Sensor set-up 1.2.8 Optional ALS-2 Connections Any of the SWS sensors can be supplied with an ambient light sensor, model ALS-2. This sensor will be connected directly to the SWS sensor, drawing its power from the sensor supply. If required, the ALS-2 will be fitted with hood heaters which will operate when the sensor hood heaters operate.

  • Page 20: Step 3 - Equipment Test

    Connect sensor earth lug to earth (this may not be necessary but can help prevent communication errors with certain PCs). 2. Connect the signal cable to a PC running the Biral Sensor Interface Software. If this is not available, use a terminal program - for example Windows® Hyper Terminal™. (For RS422/485 sensors a RS422 to RS232 converter must be used).
  • Page 21 Section 1 Sensor set-up 1. Turn the local power source "ON". If communications are working the sensor will respond with “Biral Sensor Startup” . 2. Check Data Transmission To Sensor: Send the command R? from the PC terminal to the sensor: The sensor will respond with its Remote Self-Test &...

  • Page 22: Step 4 - Configuration Options

    Two configuration bytes determine many of the configuration selections which are available for the SWS series of sensors. These two bytes are the lower bytes of the Options Word and of the Operating State Word. These are described below and their functions specified in the remainder of this section.
  • Page 23 Section 1 Sensor set-up To set this word, send command CO to enable changes and then command OPa0b0000c to set the Option Word as required. For example, send OP100000 to enable the checksum with no date and time stamp and not using RS485 (leading ‘0’s are not necessary in this command).

  • Page 24: Table 1-7 Operating State Word (Lower Byte)

    Sensor Set-up Section 1 Each bit of the lower byte of the Operating State word is defined as follows: b b b b b b b b Bit 1: 1 = Standard Mode: Data message sent automatically after calculation. 0 = Polled Mode: Data message sent only in response to "D?"' command.
  • Page 25 IN THE SENSOR FUNCTIONING INCORRECTLY Default setting for units WITH hood heaters Any combination of operating bits may be set but Biral strongly recommends that for all sensors the window demisters are always on (bits 7 and 8 set to 0).
  • Page 26 Sensor Set-up Section 1 1.4.4 Date and Time Stamp in data string By default the date and time stamp is not included at the start of the data string. This is controlled by the Options Word setting; see Table 1-6 Options Word (lower byte). To enable Date and Time stamp The sensor can be configured to generate messages with the date and time string by setting the least significant bit in the options word:...

  • Page 27: Table 1-8 Baud-Rate Configuration

    Section 1 Sensor set-up The sensor will respond with 'OK'. %ST sets the real time clock time. The format of the command is: %STHHMMSS where: - is the hours in 24 hour clock format (00..23). - is the minutes(00..59). - is the seconds (00..59). The sensor will respond with 'OK'.
  • Page 28 Sensor Set-up Section 1 1.4.6 Checksum to verify message A check sum byte can be included with messages sent by the sensor to verify that noise in the communications link has not changed the message. Generally noise is not a problem and checksum verification is not required.
  • Page 29 Section 1 Sensor set-up For Message: C1 ... Cm <cksum><crlf> The calculation is as follows:        cksum    IF <cksum> = 8 THEN <cksum> = 119 IF <cksum> = 10 THEN <cksum> = 117 IF <cksum>...
  • Page 30 Sensor Set-up Section 1 Start The ‘:’ (colon) symbol is used as a start flag which is 3A hex. Address The 2 character address is defined by the operator for the unit and programmed as specified in the set-up instructions. It can be any numeric value between 00 and 99. It is used by the unit to define the recipient of the message and by the slave to define the source of the message.
  • Page 31 Section 1 Sensor set-up the checksum is calculated as : ASCII string 42D? BYTE Values (in HEX) 34+32+44+3F Checksum is E9 One’s compliment (0xFF – 0xE9) = 0x16 Two’s compliment 0x16 + 1 = 0x17 Checksum is 0x17 (Hex) Checksum ASCII characters are “17” Transmitted string will therefore be: :42D?17<CRLF>...
  • Page 32 (see section 1.4.3, ) rather than transmitting a data message automatically. NOTE: When RS485 communications are enabled the sensor will not output the “Biral Sensor Startup” message on power up and reset. STEP 4 – Configuration Options...

  • Page 33: Table 1-9 Relay Configuration

    Section 1 Sensor set-up 1.4.9 Configuring the Relays To get the current relay configuration send the command JRO? The sensor will respond with a number which corresponds to: Value Description No Relays Configured. Fault Relay, Relay 1 triggered on visibility and Relay 2 triggered on precipitation.

  • Page 34: Step 5 - Installation

    Sensor Set-up Section 1 1.5 STEP 5 - Installation Please consider the following factors when installing the sensor: (1) Siting considerations. (2) Height of the sensor above ground. (3) Orientation of the sensor. (4) Mounting the sensor. (5) Electrical grounding. Each of these factors is covered in more detail below: 1.5.1 Siting Considerations Pollutants –...

  • Page 35: Table 1-10 Sensor Height Above Ground

    Section 1 Sensor set-up 1.5.2 Height Above Ground: The optimum height at which to mount the sensor depends on the application. The table below shows recommended heights. Application Typical height Comment Recommended height for the sensor sample volume is the 1.5 to 2 meters Highway fog-warning systems average distance of a vehicle...

  • Page 36: Figure 1-7 Sws-050 And Sws-100 Orientation

    Sensor Set-up Section 1 For sensors located in the Southern hemisphere, 180˚ should be added to the above directions. That is, for the SWS-200 and SWS-250 point the backscatter head 34˚West of South, and for the SWS-050 and SWS-100, point the forward scatter receiver directly due South.

  • Page 37: Figure 1-9 U-Bolt Mounting Method

    Section 1 Sensor set-up 1.5.4 Mounting the Sensor: On a pole Two stainless steel U-bolts and saddles are provided for securing the sensor to the top of a mast, see Figure 1-9 U-Bolt Mounting Method. The two V-block saddles oppose the U- bolt, thus providing a secure grip on the mast.
  • Page 38 Sensor Set-up Section 1 On a wall The sensor can be bolted directly to a flat surface using the four mounting holes provided. Every effort should be made to ensure that the mounting surface has minimal effect on the air flow and the precipitation flow through the sample volume. Even if mounted at the top of a wall, the airflow will be restricted, reducing the accuracy of the sensor in certain atmospheric conditions.

  • Page 39: Step 6 - Test And Commissioning

    1. Connect the power-input cable to a local power source (do not turn power source on). 2. Connect the signal wires to a PC running the Biral Sensor Interface Software. If this is not available, use a terminal program - for example Windows® Hyper Terminal™. For RS422/485 sensors a RS422 to RS232 converter must be used).

  • Page 40: Table 1-11 Remote Self-Test And Monitoring Check Fields

    Sensor Set-up Section 1 4. Turn the local power source "ON". If communications are working the sensor will respond with “Biral Sensor Startup”. 5. Check Data Transmission To Sensor: Send the command R? from the PC terminal to the sensor: The sensor will respond with its Remote Self-Test &...
  • Page 41 Sensor set-up 1.6.4 Calibration Check The sensor is fully calibrated before it leaves Biral. However, if you would like to carry out a user confidence calibration check please follow the calibration check procedure in section 5, page 54 to ensure that the MOR value changes ie the sensor responds to changes in visibility.

  • Page 42: Standard Operating Data

    Standard Operating Data Section 2 STANDARD OPERATING DATA When in standard mode a data message will be output from the sensor every measurement period (default 60 seconds). When in polled mode the same message is output only in response to the D? command. The operating mode is determined by Bit 1 of the Operating State Word.

  • Page 43: Standard Operating Data Message For The Sws-050

    Section 2 Standard Operating Data 2.1 Standard Operating Data Message for the SWS-050 The data message format for the SWS-050 is: <Date>,<Time>,SWS050,NNN,XXX,AA.AA KM,BB,CCC.CC,DDD, <cs><crlf> MESSAGE MEANING <Date> Optional Date string in the form DD/MM/YY. <Time> Optional Time string in the form HH:MM:SS. SWS050 SWS-050 message prefix.

  • Page 44: Standard Operating Data Message For The Sws-100 And Sws-200

    Standard Operating Data Section 2 2.2 Standard Operating Data Message for the SWS-100 and SWS-200 The data message format is: <Date>,<Time>,SWSz00,NNN,XXX,AA.AA KM,BB.BBB,CC,DD.D C,EE.EE KM,FFF<cs><crlf> MESSAGE MEANING <Date> Optional Date string in the form DD/MM/YY. <Time> Optional Time string in the form HH:MM:SS. SWSz00 Either SWS100 or SWS200 dependent on model.

  • Page 45: Table 2-2 Sws-100 And Sws-200 Operating Data Message Format

    Section 2 Standard Operating Data MESSAGE MEANING Present weather codes. From WMO Table 4680 (Automatic Weather Station). For SWS-200 Not Ready (first 5 measurement periods from restart) No Significant weather observed or sensor starting Haze or smoke Indeterminate precipitation type Light Drizzle Moderate Drizzle Heavy Drizzle...

  • Page 46: Standard Operating Data Message For The Sws-250

    Standard Operating Data Section 2 2.3 Standard Operating Data Message for the SWS-250 The data message format is: <Date>,<Time>,SWS250,NNN,XXXX,AA.AA KM,CC,W ,DD,EEEEE,FFF.FFF, GG.GG KM,HHH.HH,III.II,±JJJ.JJ,KKK.K C,±LLLL,MMM,NNNN,OO.OOOO, PPP<cs><crlf> MESSAGE MEANING <Date> Optional Date string in the form DD/MM/YY. <Time> Optional Time string in the form HH:MM:SS. SWS250 Model number.
  • Page 47 Section 2 Standard Operating Data MESSAGE MEANING Slight Snow Moderate Snow Heavy Snow Slight Ice Pellets Moderate Ice Pellets Heavy Ice Pellets Snow Grains Ice Crystals Slight Rain Showers Moderate Rain Showers Heavy Rain Showers Slight Snow Showers Moderate Snow Showers Heavy Snow Showers Hail or Small Hail (Graupel) Past Weather Type1 SYNOP Code:...

  • Page 48: Table 2-3 Sws-250 Operating Data Message Format

    Standard Operating Data Section 2 MESSAGE MEANING ALS signal, 1 minute average value (cd/m ). Optional, if not fitted set to ±LLLLL 99999. Self-Test and Monitoring (See section 4.2): O = Other self-test values OK. X = Other self-test fault exists. F = Forward Scatter Receiver Flooded with Light.
  • Page 49 Section 2 Standard Operating Data 2.3.1 METAR Codes CODE METAR MEANING NUMBER CODE Not Ready (first 5 minutes from restart) No significant weather observed, or sensor starting Haze, visibility greater than or equal to 1km Fog in last hour but not at time of observation Precipitation in last hour but not at time of observation Drizzle in last hour but not at time of observation Rain in last hour but not at time of observation...

  • Page 50: Table 2-4 Metar Codes

    Standard Operating Data Section 2 CODE METAR MEANING NUMBER CODE -RASN Rain (or Drizzle) and Snow, slight RASN / Rain (or Drizzle) and Snow, moderate or heavy +RASN Snow, slight Snow, moderate Snow, heavy Ice Pellets, slight Ice Pellets, moderate Ice Pellets, heavy Snow Grains Ice Crystals...

  • Page 51: Data Message Variations For Als-2

    Section 2 Standard Operating Data 2.4 Data Message Variations For ALS-2 For SWS sensors fitted with an Ambient Light Sensor, ALS-2, the data output strings are identical to the standard message with the following appended to the message, prior to the optional check sum<cs>...

  • Page 52: Commands And Responses

    Commands and Responses Section 3 COMMANDS AND RESPONSES 3.1 Sensor Commands NOTE: All commands should be terminated with <Carriage Return> and <Line Feed> (<crlf>, see paragraph 1.3). Command Function Response xxx.xx OR Send Accumulated Precipitation Message. xxxx.x (accumulated SWS-200 and SWS-250 only. precipitation in mm) Note: The accumulated Precipitation will reset to zero every 24 hours.
  • Page 53 Section 3 Commands and Responses Command Function Response Set instrument identification number displayed in Data Message. Range x = 1 to 999. (Default = 1). Note: if enter value > 999 only first 3 digits will be used. Send precipitation matrix, accumulated over the last five measurement periods.

  • Page 54: Table 3-1 Commands For Sws Series Sensors

    %STHHMMSS Set current time. See section 1.4.4 (page 16) Table 3-1 Commands for SWS series sensors 3.1.1 Command M? – Send Precipitation message This command is only available in the SWS-250 sensor. The sensor responds by sending a precipitation matrix accumulated over the last five measurement periods. This is a matrix of 16 rows with up to 21 readings, each being the number of precipitation particles of that specific size and velocity.

  • Page 55: Table 3-2 Command R? Response

    Section 3 Commands and Responses 3.1.2 Command R? - Send Remote Self-Test and Monitoring Message Example response: 100,2.509,24.1,12.3,5.01,12.5,00.00,00.00,100,105,107,00,00,00,+021.0,4063 The various fields in the response are as follows: Field 1: Space The message starts with a space. Field 2: ABC Heater state and error flags. A = 1 - Window heaters ON.

  • Page 56: Sensor Responses

    Commands and Responses Section 3 3.1.3 Command T? - Send Instrument Times Message Response: aaaa,bbbb,ccccc,dddd aaaa: Measurement interval for each operational data message (10 to 300 seconds) (default = 60). bbbb: Auxiliary measurement sample period - time between measurement of peripheral signals during measurement interval.

  • Page 57: Maintenance Procedures

    Maintenance Procedures 4 MAINTENANCE PROCEDURES The SWS series of sensors require very little maintenance. The following sections detail the checks that are advisable to ensure continued good operation of the sensor. The frequency of these checks depends upon the location and environmental conditions under which the sensor operates.

  • Page 58: Figure 4-1 Hood Heater

    When the temperature is above the switching temperature the heaters will be switched off but may be controlled using a PC running the Biral Sensor Interface Software. If this is not available, use a terminal program - for example Windows® Hyper Terminal™. The heaters may be switched on temporarily using the command DHO and off again using the command DHX, see section 3.1.

  • Page 59: Self-Test Codes

    Section 4 Maintenance Procedures The SWS-050 and SWS-250 sensors are additionally fitted with receiver window monitors. These monitor the forward scatter window and, if fitted, the back scatter window. This provides better accuracy if there is likely to be different contamination on each window.

  • Page 60: User Confidence Checks

    4.3 User Confidence Checks The following user confidence checks require bi-directional communications with a PC running the Biral Sensor Interface Software. If this is not available, use a terminal program - for example Windows Hyper Terminal. It is suggested that these should be carried out at least every year, to provide continuing confidence in the correct operation of the system.

  • Page 61: Figure 4-2 Transmitter Hood With White Card

    Section 4 Maintenance Procedures THIS PROCEDURE CAN ONLY BE COMPLETED IF A SUITABLE SWS CALIBRATION KIT AND PC ARE AVAILABLE 4.3.2 Window Monitor Checks All SWS sensors monitor the transmitter window for contamination. The values measured are used to adjust the MOR value, and are also used to determine when the windows should be cleaned.
  • Page 62 Maintenance Procedures Section 4 Step 7. Remove the white card. Receiver Window Monitor(s) This procedure is used for the forward scatter receivers on the SWS-050 sensor (optional on the SWS-100) and both the forward and back scatter receivers on the SWS-250 sensor (optional on the SWS-200).
  • Page 63 Section 4 Maintenance Procedures Step 2. Send the command: R? Step 3. Verify that the value in the 'Forward (Back) Scatter Receiver Background Brightness' field is less than 00.06. (forward scatter is field 8, backscatter is field 9, see section 3.1.2). Step 4.

  • Page 64: Calibration Procedures

    SWS-200, but the assembly is identical for all other models in this range. 5.1 Calibration Check The following instructions show how to check the calibration of a SWS series sensor. This procedure can only be completed with: A SWS Calibration Kit Connection to a PC running the Biral Sensor Interface Software, or, if this is not available, terminal emulation software (such as Windows ®...

  • Page 65: Figure 5-1 Assembly Of Calibration Reference Plaque

    Section 5 Calibration Procedures CALIBRATION CHECK NOTES PLEASE READ THESE NOTES BEFORE CONTINUING The MOR (Meteorological Optical Range or visibility) values depend heavily on the location and prevailing weather conditions and should only be carried out with the sensor: MOUNTED OUTSIDE AND ON A CLEAR DAY (VISIBILITY>10KM) POWERED FOR AT LEAST 1 HOUR NOT LOCATED NEAR A WALL OR OTHER OBSTRUCTION NOT RECEIVING OPTICAL REFLECTIONS (FROM SURFACES OR...
  • Page 66 Calibration Procedures Section 5 Note: All commands should be terminated with <Carriage Return> and <Line Feed> <crlf>, (see Paragraph 1.3). STEP 1: Clean all windows on the sensor using pure alcohol (propanol) and soft cloth or tissue, preferably lens tissue. Check the cleanliness using a portable light if possible.
  • Page 67 Section 5 Calibration Procedures If the sensor is operating in the polled mode, send “D?” command at 60 seconds STEP 10: intervals. (If the sensor is set to automatically output data then the sensor will output data every 60 seconds.) ) data message from the sensor.

  • Page 68: Sensor Re-Calibration

    Calibration Procedures Section 5 5.2 Sensor Re-calibration RE-CALIBRATING THE METEOROLOGICAL OPTICAL RANGE SHOULD ONLY BE CARRIED OUT IF THE SENSOR HAS FAILED A CORRECTLY PERFORMED USER CONFIDENCE CHECK WARNING ERRORS DURING THIS RE- CALIBRATION PROCEDURE WILL CAUSE THE SENSOR TO GIVE INCORRECT DATA BEFORE CONTINUING ENSURE THAT THE SENSOR: 1.
  • Page 69 Section 5 Calibration Procedures STEP 5. Enter the forward scatter calibration value from the calibration plaque. STEP 6. SWS-200 and SWS-250 Only Sensor replies: ENTER BACK SCAT VALUE FORM: XXX.XX Enter the back scatter calibration value from the calibration reference plaque. STEP 7.

  • Page 70: Precipitation Amount Calibration

    Calibration Procedures Section 5 5.3 Precipitation Amount Calibration Note: All commands should be terminated with <Carriage Return> and <Line Feed> <crlf>, (see Paragraph 1.3). This section is only applicable to models SWS-200 and SWS-250. This process provides for adjusting the calibration factor of the sensor precipitation measurement.

  • Page 71: Product Overview

    PRODUCT OVERVIEW 6.1 SWS-050, SWS-100, SWS-200 and SWS-250 Present Weather Sensors There are four models in the SWS series of present weather sensors, the SWS-050, SWS- 100, SWS-200 and SWS-250. They all use the same basic opto-mechanical and electronic components and have an optical transmitter and forward scatter receiver. The SWS-200 and SWS-250 also have a backscatter receiver to aid in precipitation identification.

  • Page 72: Figure 6-2 Sws-200 And Sws-250 Capabilities

    Product Overview Section 6 Sensor Model Capability SWS-200 Visibility Precipitation type identification 1 Fault relay switch 1 Relay for visibility 1 Relay for precipitation or visibility This model has an extra backscatter receiver for: Rain rate Snowfall rate Precipitation accumulation SWS-250 Visibility Precipitation type identification...
  • Page 73 Section 6 Product Overview 6.1.1 Instrument Components Each sensor has been engineered and manufactured with high-reliability components to provide accurate measurements under all weather conditions. Its rugged aluminium powder-coated construction is intended to serve you in the severest of environmental conditions throughout the long life of the instrument.

  • Page 74: Sensor Features

    These may be ordered if required. The length must be specified at time of order. Ambient Light Sensor The Biral ALS-2 ambient light sensor can be readily integrated with any SWS sensor. This provides an accurate measure of the prevailing apparent light intensity in any specific direction.

  • Page 75: Present Weather Measurements

    Section 6 Product Overview Ease of Maintenance and Calibration: Routine maintenance, including a check on calibrations, is performed in a matter of a few minutes. A re-calibration, if required takes only slightly longer and is easily performed by one person. 6.3 Present Weather Measurements 6.3.1 Present Weather Definition The term "Present Weather"...

  • Page 76: Precipitation Measurements

    Product Overview Section 6 MOR is less than 1 km, then fog (30) is indicated in the output message. If the MOR is between 1 and 10 km, then haze (04) is indicated in the output message. If MOR is greater than 10 km, no obstruction to vision is indicated.

  • Page 77: Table 6-2 Precipitation Measurement Limits

    Note: If a sensor is intended for installation in a country where the definitions of precipitation intensity differ from the U.S. definitions, it is possible for the sensor to be produced with the appropriate definitions installed. BIRAL must be informed of this requirement at the time of order.

  • Page 78: Table 6-3 Us Precipitation Intensity Definitions

    Product Overview Section 6 Snow Visibility equal to or greater than 5/8 statute miles, 0.55 nautical Slight miles, or 1,000 meters. Visibility 5/16 to 1/2 statute miles, 0.25 to 0.5 nautical miles, or Moderate 500 to 900 meters. Visibility equal to or less than 1/4 statute miles, 0.2 nautical miles, Heavy or 400 meters.

  • Page 79: Table 6-4 Sws-100 Wmo Codes

    Section 6 Product Overview Present Weather Codes – SWS-100 Code Description Not Ready (first 5 measurement periods from restart). No Significant weather observed or sensor starting. Haze or smoke. Fog. Indeterminate precipitation type. Drizzle. Rain. Snow. Table 6-5 SWS-100 WMO Codes Present Weather Codes –...
  • Page 80 Product Overview Section 6 Present Weather Codes – SWS-250 Code METAR Description Not Ready (first 5 minutes from restart). No significant weather observed, or sensor starting. Haze, visibility greater than or equal to 1km. Fog in last hour but not at time of observation. Precipitation in last hour but not at time of observation.

  • Page 81: Table 6-6 Sws-250 Wmo And Metar Codes

    Section 6 Product Overview Code METAR Description Snow, moderate. Snow, heavy. Ice Pellets, slight. Ice Pellets, moderate. Ice Pellets, heavy. Snow Grains . Ice Crystals. -SHRA Rain Showers, slight. SHRA Rain Showers, moderate. +SHRA Rain Showers, heavy . -SHSN Snow Showers, slight. SHSN Snow Showers, moderate.
  • Page 82 Section 6 6.5.4 Precipitation Recognition Matrix The SWS series of sensors measure the amplitude and duration of the light pulse created by each precipitation particle as it falls through the sample volume. From the amplitude and duration it then determines the particle size and velocity. The size and velocity...

  • Page 83: Figure 6-3 Precipitation Recognition Matrix

    Section 6 Product Overview Figure 6-3 Precipitation Recognition Matrix General size/velocity characteristics of various types of precipitation displayed on the precipitation recognition matrix. Precipitation Measurements...

  • Page 84: Sensor Specifications

    Product Overview Section 6 6.6 Sensor Specifications The specifications for all versions of the SWS sensor series are summarised in the following pages. Where certain specifications are only applicable to certain models within the range, this is stated within that table. Visibility Measurements (MOR) and Precipitation Measurements Function Details...

  • Page 85: Instrument Characteristics

    Section 6 Product Overview Maintenance Function Details MTBF (Calculated) 52,500 hrs (6 years). Calibration Check 6 months. Clean Windows 3 months. Remote Self-Test Monitoring Included. Table 6-8 Sensor Specifications 6.7 Instrument Characteristics Physical Function Details Scattering Angle 45 with ± 6 cone angle Sample Volume 400 cm Weight...

  • Page 86: Table 6-7 Instrument Characteristics

    Product Overview Section 6 Temperature Sensor Function Details Type Circuit mounted IC Range -60°C to 100°C Power Requirements Function Details Power Source Sensor (Voltage) 9V to 36V DC (24V typical) Power Source Sensor (Power) 3.5 W Power Source Hood Heaters (Voltage) 24V DC or AC SWS-050 and SWS-100 24W Power Source Hood Heater (Power)

  • Page 87: Digital Communication Interface

    Section 6 Product Overview 6.8 Digital Communication Interface Communication Protocol Function Details Interface Type RS232C, (Full Duplex) Optional RS422/RS485 Communication Parameters: Function Details Baud Rates 1200 Baud to 57K6 Baud Data Bits Parity None Stop Bits Flow Control None Message Termination <CR,LF>...

  • Page 88: Analog Outputs

    Product Overview Section 6 6.9 Analog Outputs These are available only on models SWS-100 and SWS-200. Function Details Voltage 0 to 10 Volts out. Equivalent to 0 to MOR MAX. 4 to 20 mA. Equivalent to 0 to MOR (option) Current 0 to 20 mA.

  • Page 89: Sensor Remote Self-Test Capabilities

    Section 6 Product Overview 6.11 Sensor Remote Self-Test Capabilities  Optical Source Power.  Forward Scatter Receiver Sensitivity.  Back Scatter Receiver Sensitivity (not SWS-050 or SWS-100).  Transmitter Window Contamination.  Forward Scatter Receiver Window Contamination (optional on SWS-100 and SWS- 200).

  • Page 90: Sws Sensors - External Dimensions

    Product Overview Section 6 6.12 SWS Sensors – external dimensions All SWS sensors have dimensions as shown below. The diagrams show the SWS-200 and SWS-250 versions. The SWS-050 and SWS100 versions do not have the back scatter hood and window. Backscatter receiver Figure 6-4 External Dimensions of SWS-sensors (Dimensions in mm) SWS Sensors External Dimensions...

  • Page 91: Index

    Section 7 Index INDEX CCESSORIES Ambient Light Sensor ..........................64 Calibration Kit ............................63 Mains Adapter ............................64 Power and Signal Cables ........................... 64 Transit Case ............................... 63 ............................. FTER ALES UPPORT ........................, 9, 41, 64 MBIENT IGHT ENSOR Data Message Extension ..........................
  • Page 92 Index Section 7 ..........................3 LECTRICAL ONNECTIONS EMC C ............................8 OMPLIANCE ........................74 NVIRONMENTAL PECIFICATION ............................. 10 QUIPMENT ................................47 EATERS Hood Heaters ............................47, 63 Changing Defaults ..........................15 Connecting Power Supply ........................5 Window heaters (de-misters) ........................47 ........................33, 34, 43 DENTIFICATION NUMBER ..............................
  • Page 93 Section 7 Index Connections for 0 / 4-20mA analogue output ....................8 Connections for Power Supply ........................5 Connections for Relay ..........................7 Connections for RS232 or RS422 ........................ 5 ............................ 74 OWER EQUIREMENTS ......................60 RECIPITATION MOUNT ALIBRATION ........................66 RECIPITATION EASUREMENTS .......................
  • Page 94 Notes:...

This manual is also suitable for:

Sws-200Sws-100Sws-250Sws-050

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