Hydrological Services Pty Ltd

Heater Model TB323LP

For Model TB3 Tipping Bucket Raingauge

Presented By

W.R. Barratt

CEOCopyright

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Introduction (TB323LP)

Latest innovation to measure snowfall Converts snow to liquid (water) Uses traditional tipping bucket raingauge Thermostatically controlled heating

element

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Principle Of Snow Formation

Large snowflakes can be formed by the collision of ice crystals within clouds (aggregation process)

Smaller snowflakes are formed by the Bergeron-Findeisen process

For snow to reach the ground the air temperature must be no more than 35.6oF (2°C)

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Principle Of Snow Formation Cont‘d

One would expect the falling snow to melt as soon as the temperature rises above freezing, but this is not so. As the melting process begins, the air around the snowflake is cooled.

The heaviest falls of snow tend to occur when the air temperature is between 32 and 35.6oF (2°C)

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Principle Of Snow Formation Cont‘d

Individual ice crystals and snowflakes can be the shape of prisms, plates or stars - but all have 6 sides

12 inches (304.8 mm) of fresh fallen snow, when melted, is equivalent to 1.2 inches (30.48mm) of rainfall

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Features Of The TB323 LP

More effective method of measuring snowfall

Increase accuracy of measuring snowfall ± 2% based on the principle of the tipping bucket raingauge.

Avoid freezing of gauge in cold climates. Hence, eliminates subsequent loss of precipitation records

Gauge can be used for rainfall and snowfall (2 in 1)

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Features Of The TB323 LP Cont’d

Immediate measure of snowfall. Hence, low volume of snowfall is detected and measured

Heater unit is ON only between +14oF (-10°C) and +40oF (+4.5°C)

DC powered for remote areas Real time data using

appropriate RTU’s and software

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Features Of The TB323 LP Cont’d

Snow sensor which activates the heating elements inside the raingauge only when snow events occur.

Duty cycle heating to reduce power after initial warm up.

Total power consumption is generally reduced by the combination of the above two features

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Snow Sensor

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Specifications

Ambient temperature range +158 to –40oF (+70 to –40oC) Preset ON temperature 39.2oF (+4oC) Preset OFF temperature 40oF (+4.5 oC) Preset DE-ACTIVATION temperature 14oF (-10oC)(cuts out below this

temperature) Heating elements are self limiting. Power generated 50 watts (100 watts at initial 90 minute

warm up) Voltage requirements 12 volts AC/DC nominal Heating Current requirements 4.2 amps average (40% duty cycle) (8.5 amps

at initial warm up) Average Current Requirements 1.44 Amps long term average.

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Typical Power Requirements

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Number of Events per Week 5 events (typical)Length of Event (6 to 18 hours) 10 hours (typical)Burst Time (initial warm-up) 1.5 hoursBurst Current (100%) 8.5 amperesDuty Cycle Time 8.5 hoursDuty Cycle % 40 %Duty Cycle On Current 10.5 amperes

Amp hours per week (Burst) 63.75 Ah/wkAmp hours per week (Cycling) 178.50 Ah/wk

Amp hours per week (Total) 242.25 Ah/wkAmp hours per Day 34.61 Ah/dayAverage current over one week 1.44 amperes

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Typical Power Requirements Cont’d

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Number of Events per Week 1 eventLength of Event (6 to 18 hours) 10 hours (typical)Burst Time (initial warm-up) 1.5 hoursBurst Current (100%) 8.5 amperesDuty Cycle Time 8.5 hoursDuty Cycle % 40 %Duty Cycle On Current 10.5 amperes

Amp hours per week (Burst) 12.75 Ah/wkAmp hours per week (Cycling) 35.70 Ah/wk

Amp hours per week (Total) 48.45 Ah/wkAmp hours per Day 6.92 Ah/dayAverage current over one week 0.29 amperes

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Principle Of Operation

Initial State Rainfall OnlyThe Hydrological Services Tipping Bucket Raingauge (TB3) is recognised as the standard for measuring rainfall and precipitation in remote and unattended locations. The TB3 raingauge operates on the tipping bucket principle. A receiver of 200mm diameter collects the rainfall, which is strained by a metal gauze before being passed through the syphon to the tipping bucket measuring system. Tips of the plastic bucket occur with each 0.2mm, 0.5mm or 0.01 inch of precipitation collected. A reed switch detects these events and produces a momentary contact closure signal for:

- logging in our Rainfall Data Logger- transmission by our Radio Reporting Raingauge, or - display on our Rainfall Counter

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Principle Of Operation Cont’d

Snowfall State:

The TB323LP kit is designed for use with the TB3 raingauge to accurately measure snowfall by converting snow into liquid.

The device is basically a thermostatically controlled heating element, that raises the temperature of the interior of the raingauge, funnel and catch to avoid the freezing of the gauge in cold climates with subsequent loss of precipitation records. When the ambient temperature drops below a preset value (+ 4oC), the snow sensor mode is activated. The heater elements remains “off” until snow is present in the catch area triggering the initial heating period (100% power) followed by 40% duty cycle until there is no snow remaining in the catch. At the completion of the heating cycle the unit will return to wait mode until triggered by a snow event. The system will be de-activated when temperature drops below (-10oC) or above (+4.5oC) nominal. This combination of duty cycle and snow sensor is designed to reduce power consumption.

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data

Experiment: The testing of the TB323LP was done in Hydrological Services

environmental chamber. The environmental chamber was set at a steady temperature of –10oC.

Three heating elements were used. Two elements were placed below the funnel and the third element was placed at the base of the gauge beneath the bucket.

To be more conservative in testing, Hydrological Services used shaved ice which is 3 times less dense than the water where snow is 10 times less dense than water . The raingauge funnel was loaded with shaved ice.

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

Two insulating sleeves were used one inside the enclosure and another outside the enclosure to reduce heat loss.

The tests were repeated for 2 weeks to ensure repeatability and calibration of the raingauge was maintained.

The bucket tips, funnel temperatures and ambient temperatures were recorded over the period to evaluate the effectiveness of the heating and melting processes.

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

Key to data table:

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Date 27/09/2004Test

Duration 140 minutes n/sNo Snow Detected

Cut Off Temp -8 s/d

Snow Detected

On Temp 4 off

Heating Element

Off

Cut Off Temp 11 f/p

Heating Element

On

Data in table

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

Test Data:

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TimeAmbient

TempFunnel Temp

Snow Sensor

90 Minutes

Warm Up

Heating Element Status

10:09:26 -11 -3.1 n/s 0 off 10:09:55 -10.4 -0.7 s/d 90 f/p 10:10:00 -10.3 -0.4 s/d 90 f/p 10:11:02 -9.9 0.5 s/d 89 f/p 10:12:04 -9.4 1.3 s/d 88 f/p 10:13:00 -9.6 1.7 s/d 87 f/p 10:14:01 -9.5 2.5 s/d 86 f/p 10:15:03 -10.1 3.4 s/d 85 f/p 10:16:05 -10.3 4.5 s/d 84 f/p 10:17:01 -10.5 5.3 s/d 83 f/p 10:18:02 -9.9 6.1 s/d 82 f/p

Heater Off initial state

Heater On 90 minutes initial warm up. Snow Detected "s/d". Funnel Temperature starts to increase at this point.

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

10:19:04 -10.1 6.9 s/d 81 f/p 10:20:00 -9.4 8.4 s/d 80 f/p 10:21:02 -9.7 9.7 s/d 79 f/p 10:22:04 -9.8 10.8 s/d 78 f/p 10:23:00 -10 11.5 s/d 77 f/p 10:24:02 -10.5 12.4 s/d 76 f/p 10:25:03 -10.3 12.4 s/d 75 f/p 10:26:05 -9.9 12.8 s/d 74 f/p 10:27:01 -9.5 13.6 s/d 73 f/p 10:28:03 -9.6 13.9 s/d 72 f/p 10:29:05 -9.1 13.5 s/d 71 f/p 10:29:10 -9.5 13.5 s/d 71 f/p 10:29:16 -9.9 13.6 s/d 71 f/p 10:29:21 -10.3 13.6 s/d 71 f/p 10:29:27 -10.2 13.6 s/d 71 f/p 10:29:33 -10.1 13.8 s/d 71 f/p 10:29:38 -9.7 13.9 s/d 71 f/p 10:29:44 -9.5 14 s/d 71 f/p 10:29:49 -9.6 14 s/d 71 f/p 10:29:55 -9.5 14 s/d 71 f/p

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

10:30:01 -10 14 s/d 70 f/p 10:31:02 -9.9 15 s/d 69 f/p 10:32:04 -9.7 16 s/d 68 f/p 10:33:00 -9.8 16.4 s/d 68 f/p 10:34:02 -9.7 13.9 s/d 67 f/p 10:35:04 -9.4 13.5 s/d 66 f/p 10:36:00 -9.7 14 s/d 65 f/p 10:37:02 -9.8 16 s/d 64 f/p 10:38:04 -10 16.4 s/d 63 f/p 10:39:00 -10.4 16.4 s/d 62 f/p 10:40:02 -10.5 16 s/d 61 f/p 10:41:03 -9.9 16 s/d 60 f/p 10:42:05 -9.9 15.9 s/d 59 f/p 10:43:01 -9.3 16.2 s/d 58 f/p 10:44:03 -9.6 16.3 s/d 57 f/p 10:45:04 -9.7 16 s/d 56 f/p 10:46:00 -9.7 15.9 s/d 55 f/p 10:47:02 -9.9 12 s/d 54 f/p 10:48:04 -10.3 11.9 s/d 53 f/p 10:49:00 -9.7 12.7 s/d 52 f/p 10:50:02 -9.9 12.9 s/d 51 f/p 10:51:03 -9.1 12.8 s/d 50 f/p 10:52:05 -9.1 13 s/d 49 f/p 10:53:01 -9.5 13.1 s/d 48 f/p 10:54:03 -9.8 12.8 s/d 47 f/p 10:55:05 -9.9 13.9 s/d 46 f/p 10:56:01 -10.2 14 s/d 45 f/p 10:57:02 -9.8 13.6 s/d 44 f/p 10:58:04 -9.6 13.5 s/d 43 f/p 10:59:00 -9.1 13.5 s/d 42 f/p

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

11:00:02 -9.1 13.7 s/d 41 f/p 11:01:04 -9.5 13.2 s/d 40 f/p 11:02:00 -10.1 13.4 s/d 39 f/p 11:03:01 -9.8 13.5 s/d 38 f/p 11:04:03 -9.9 12.8 s/d 37 f/p 11:05:05 -10 12.8 s/d 36 f/p 11:06:01 -9.8 12.4 s/d 35 f/p 11:07:03 -9.7 11.2 s/d 34 f/p 11:08:04 -9.5 10.3 s/d 33 f/p 11:09:00 -9.8 10.3 s/d 32 f/p 11:10:02 -10.3 13.1 s/d 31 f/p 11:11:04 -10.2 12.8 s/d 30 f/p 11:12:00 -10.4 14.8 s/d 29 f/p 11:13:02 -9.9 15.9 s/d 28 f/p 11:14:03 -9.9 17.2 s/d 27 f/p 11:15:05 -9.1 19.1 s/d 26 f/p 11:16:01 -9.1 8.8 s/d 25 f/p 11:17:03 -9.5 8.5 s/d 24 f/p 11:18:05 -10 8.9 s/d 23 f/p 11:19:01 -10.7 7.6 s/d 22 f/p 11:20:02 -9.9 8.5 s/d 21 f/p 11:21:04 -9.7 8.1 s/d 20 f/p 11:22:00 -9.5 6.8 s/d 20 f/p 11:23:02 -9.1 7.6 s/d 19 f/p 11:24:04 -9.1 10.2 s/d 18 f/p 11:25:00 -9.5 12.8 s/d 17 f/p 11:26:01 -10 14.5 s/d 16 f/p 11:27:03 -10.1 16.3 s/d 15 f/p 11:28:05 -10.3 20.5 s/d 14 f/p 11:29:01 -9.9 21.9 s/d 13 f/p 11:30:02 -9.9 23.6 s/d 12 f/p

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

11:30:02 -9.9 23.6 s/d 12 f/p 11:31:04 -9.1 18.8 s/d 11 f/p 11:32:00 -9.1 18.3 s/d 10 f/p 11:33:02 -9.7 16.9 s/d 9 f/p 11:34:04 -10 19.9 s/d 8 f/p 11:35:00 -9.8 23.7 s/d 7 f/p 11:36:02 -9.8 25.9 s/d 6 f/p 11:37:03 -9.7 29.4 s/d 5 f/p 11:38:05 -9.5 31.9 s/d 4 f/p 11:39:01 -9.1 32.7 s/d 3 f/p 11:40:03 -9.1 32.6 s/d 2 f/p 11:41:05 -9.6 32.3 s/d 1 f/p 11:42:01 -10 32.2 s/d 27 off 11:43:02 -10.9 31.1 s/d 26 off 11:44:04 -10.7 31.1 s/d 24 off11:44:38 -9.9 31.9 s/d 15 f/p11:44:43 -9.9 31.9 s/d 9 f/p11:44:49 -9.1 32 s/d 3 f/p11:44:55 -9.1 31.9 s/d 34 off11:45:00 -9.5 32.1 s/d 28 off11:45:06 -9.9 32.1 s/d 23 off11:45:11 -10.3 32.2 s/d 17 off11:45:17 -9.9 32.1 s/d 11 off

40% duty cycle start here. 90 minutes are over. Snow still available in funnel. Power Consumption is active

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Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Test Data Cont’d

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11:46:58 -9.7 30.3 s/d 31 off11:47:04 -9.5 30.3 s/d 25 off11:47:09 -9.3 30.2 s/d 20 off11:47:15 -9.4 30.2 s/d 14 off11:47:20 -10 30.2 s/d 9 off11:47:26 -10.3 29.9 s/d 3 off11:48:00 -10.8 29 n/s 0 off11:48:56 -9.4 27.2 n/s 0 off11:49:01 -9.3 27.1 n/s 0 off11:50:03 -9.1 25.5 n/s 0 off11:50:59 -9.5 24.4 n/s 0 off11:51:55 -10 25 n/s 0 off11:52:57 -10.2 24 n/s 0 off11:53:59 -10.9 22.3 n/s 0 off11:54:55 -9.4 20.6 n/s 0 off11:55:00 -9.3 20.4 n/s 0 off11:56:02 -9.1 18.8 n/s 0 off11:57:04 -10.2 17.2 n/s 0 off11:58:00 -10 17.5 n/s 0 off11:59:01 -10.1 17.6 n/s 0 off12:00:03 -10.2 16.4 n/s 0 off12:01:05 -9.7 17.6 n/s 0 off12:02:01 -10 15.9 n/s 0 off

40% duty cycle is overHeater Element is Off. Funnel start cooling down

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004 Copyright

Temperature Vs Time

-20

-10

0

10

20

30

40

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Minutes

Deg

ree

Cel

ciu

s

Ambient Temperature Funnel Temperature tips

End of 90 minutes warm up. Start of 40% duty cycle.Start of 90 minutes warm up.

End of 40% duty cycle. Heater element turned off.

The red line represents the bucket tips event vs. time

GRAPH 1

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Bucket Tips Vs Time

0.00

5.00

10.00

15.00

20.00

0 10 20 30 40 50 60 70 80 90

Time (minutes)

Tim

e D

iffe

ren

ce B

etw

een

T

ips

(min

ute

s)

Bucket Tips

Normal behaviour of bucket tips

GRAPH 2

Hydrological Services Pty Ltd, Sydney, AustraliaIssue1: 6/10/2004

Future Directions

All operating parameters used by the Micro-processor controlled TB323LP are factory set. However, they may be adjusted by the customer using a RS232 to RS485 converter with appropriate procedure.

SDI-12 comms will be shortly introduced to allow monitoring of the TB323LP heating unit as well as direct manual control or parameter modification in real-time.

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