Instrument Introduction
Tipping bucket rain sensor is a kind of hydrological, meteorological instruments, used to measure the natural rainfall, and at the same time the rainfall will be converted into digital information output expressed in the form of switching quantity to meet the needs of information transmission, processing, recording and display. Domestic first successfully developed 0.2, 0.5mm tipping bucket rain gauge, can be used for national hydrology, meteorological station network rainfall data long-term collection of rainfall sensors.The tipping bucket rain gauge is a primary instrument for precipitation measurement, and its performance meets the relevant requirements of the national standard GB/T11832-2002 "Tipping Bucket Rain Gauge" and the national standard GB/T11831-2002 "Hydrological Measuring and Reporting Device Telemetric Rain Gauge".
The instrument and the recording or display part of the matching, can be wired rainfall data transmission, display, self-record.It can be used with wireless automatic water condition measuring and reporting system as the sensor of rain condition telemetry and flood reporting in specialized stations. Widely used in the country's hydrological stations, and batch exported to the East and West countries, won the national utility model patent.This type of rainfall sensor by the China Meteorological Administration Industrial Development and Equipment Department of the selection test, assessment, proved that the stability of performance, performance has reached the international advanced level.
Background
Precipitation is an important meteorological element, and the observation of precipitation is of great significance both for meteorological, hydrological, oceanic and environmental observation and for the safety of aviation and railroad transportation.Rain gauge is an important instrument for observing precipitation, and its accuracy is directly related to the reliability of the measured data, especially in the test of the effect of artificial rainfall and meteorological research, the accuracy of its measurements is particularly important.To ensure the accuracy and reliability of the rain gauge, the rain gauge calibration is very necessary.At present, the calibration of the rain gauge is mainly the use of standard containers or high precision tipping bucket rain gauge, there are also manual methods of calibration through the measuring cup, the whole process is inefficient and prone to human error, so there is a need for a calibration instrument that can automatically generate the required rainfall.
Working Principle
The tipping bucket rain gauge is a telemetric rainfall instrument composed of a sensor and a signal recorder, which consists of a water bearer, an upper tipping bucket, a metering tipping bucket, a counting tipping bucket, a reed switch, etc.; and a recorder, which consists of a counter, a recording pen, a self-timer clock, and a control circuit board.
The working principle is: rainwater from the top of the water bearer into the water bearer, falling into the water funnel, through the funnel mouth into the hopper, when the amount of water reaches a certain height (for example, 0.01 millimeters), the hopper loses its balance and tumbles over.And every time the dumping bucket dumping, make the switch on the circuit, to the recorder to deliver a pulse signal, the recorder control from the pen to record the rainfall, and so on and so forth can be measured down the rainfall process.
Specificities
The tipping bucket rain gauge is widely used because of its high degree of automation, the timeliness of obtaining precipitation, and the ease of saving and transmitting rainfall data.In addition, mountain in the tipping bucket type rain gauge is suitable for digitization method, so it is especially convenient for automatic weather station, tipping bucket type rain gauge measuring rain intensity range is not more than 4.0 mm/min, the minimum resolution is 0.1 mm.
With strong anti-interference ability, all outdoor design, high measurement accuracy, large storage capacity, convenient networking, fully automatic unattended, stable operation and so on.
Effect
(1) The tipping bucket rainfall sensor is used to measure the natural rainfall, and at the same time the rainfall will be converted into digital information output in the form of switching quantity to meet the needs of information transmission, processing, recording and display.
(2) Tipping bucket rainfall sensor is suitable for meteorological stations (stations), hydrological stations, agriculture, forestry, national defense and other relevant departments to be used for remote measurement of liquid precipitation, precipitation intensity, precipitation start and end time.
(3) Used for flood control, water supply scheduling, power station reservoir water management for the purpose of hydrological automatic reporting system, automatic field station, for precipitation measurement sensor.
Precautions for use
(1) Use the special cleaning pen for the rain sensor to clean the rain catching port at regular intervals to prevent debris from blocking it.
(2) The instrument is placed indoors, or in the field work is sure that no rainy days, in order to prevent dust from falling into the rain catchers, the available tube cover will cover the mouth of the device.
(3) The axial working clearance of the supporting shaft of the tipping bucket part should be checked frequently, too big or too small will affect the normal work of the tipping bucket part.Two M3x10 cylindrical head set screws should be careful to tighten, so as to avoid malfunctioning of the instrument.
Error analysis
The main sources of error
As an instrument for measuring rainfall, the tipping bucket rain gauge, due to the degree of process and design defects itself, errors are inevitable, and what we have to do is to make it controlled within the acceptable range.There are two main reasons for the error of tipping bucket rain gauge, one is the measurement of the tipping angle of the tipping bucket is large due to; the second is the measurement of the tipping bucket and the upper tipping bucket rotation frequency.
These two are because of the rain in the measurement process, part of the outflow is not in the counting range, which leads to the cause of the measurement error.In addition, the splashing of water from raindrops hitting the rain gates and the evaporation of rainfall are also contributing factors to the error.
Distribution of Error
According to the design principle of the tipping bucket rain gauge, it can be seen that it mainly utilizes the fixed volume conversion, each time the tipping is U. 1 mm, and the counting is controlled through the balance to achieve the purpose of measuring the rainfall.
It is known from the study that the measurement results obtained in the case of the instrument commissioned accurately with 1 mm/min rain intensity as the tuning point, and then in the case of 2.5 mm/ mi n and 4 mm/min rain intensity have a large error, while the instrument commissioned accurately with 4 mm/ min rain intensity as the tuning point, and then in the case of the other two rain intensities have a certain degree of error but the difference is not very large, according to the previously mentionedGJB requirements, the maximum allowable error is divided into two classes: in the rainfall of 10 mm and below is 0.4 mm; in the rainfall of more than 10 mm is 4% of the GJB requirements, it can be learned that the former in the tuning point of the rain outside the intensity of the measurement results exceeded the maximum permissible range, so it is invalid; the latter to 4 mm/min for the tuning of the pilot, in different rainfall conditions to get the measurement results of error within the permissible value, so it can be used as a valid instrument.The latter, with 4 mm/min as the tuning point, can be used as valid data because the error in the measurement results obtained under different rainfall intensities is within the allowable value.
Analysis of the causes of error
In the tipping bucket rain gauge for rainfall measurement, the only change is the measurement of the range of the tipping bucket, but when we complete the commissioning of its range is fixed, in the measurement of the tipping bucket for a counting process, that is, it is in the process of turning over, if there is still rainfall in the hopper, a part of the rainfall will be lost along with the flip, and this part of the rainfall is regarded as invalid, and is not counted, which results in the final results of the measurement of the bias is small!This leads to a small measurement result, as evidenced by our experimental data.Then, to solve this problem must make the measurement of the tipping angle of the tipping bucket that tipping angle to reach the minimum or in the measurement of the tipping bucket tipping process, to ensure that there is no rain in the funnel, that is, to ensure that the upper tipping bucket and measurement of the tipping bucket of the four reservoirs of the same range.But the measurement of the tipping angle of the tipping bucket is unavoidable, so can only use the latter to reduce the error, and this process needs to be resolved in the commissioning, must make the upper tipping bucket turn over once through the rain only and make the measurement of the tipping bucket is just turned over, after the completion of this stage of debugging, then the measurement of the tipping bucket will not be ineffective in the process of turning over the loss of rainwater.
In a rain emphasizes the pilot, debugging is completed and ensure that the upper tipping bucket and measuring tipping bucket up and down the same, in the measurement process under different rainfall conditions, there will still be a measuring tipping bucket when the funnel is turned over a small amount of rainwater in the phenomenon, which in turn leads to the phenomenon of the measurement results are small.Tipping bucket rain gauge in the funnel to play a buffer role, that is, to ensure that the rain through the throttle tube flow rate is stable, so the flow rate of rain through the throttle tube to a certain extent is fixed, and the frequency of the upper tipping bucket with the size of the size of the rain intensity is directly proportional to the upper tipping bucket tipping frequency is higher than the measurement of the frequency of the tipping bucket tipping, i.e., the flow rate of rain through the throttle tube resulting in the measurement of the tipping bucket to achieve the frequency of frequency to keep pace with the frequency, there will be an invalid loss of rainwater.There will be ineffective loss of rainwater phenomenon.It can be seen that it is necessary to ensure that the turning frequency of the metering hopper is not lower than that of the upper hopper in order to obtain more effective measurement results.Therefore, in the case of low rain intensity commissioning of the instrument, in the high rain intensity will appear in the measurement results than the test measurement point is much smaller than the phenomenon, and even make the instrument calibration is unqualified; in the case of high rain intensity commissioning of the instrument, because it has been circumvented on the hopper turning frequency is higher than the measurement of the turning frequency of the bucket, because of the manual commissioning is not precise enough, although the results of the measurement will be inaccuracies, but can be guaranteed to be within the error, and its results will be bigger with the decrease of rain intensity, the reason is that the upper hopper turning frequency is not lower than the measurement of the flip frequency of the hopper.And the results will be with the rain intensity of the reduction and large, the reason is that the upper tipping bucket turning frequency is reduced, can fully ensure that the funnel does not appear in the water storage phenomenon.
Improved methodology
The reason for the error is that the turning frequency of the metering hopper is less than that of the upper hopper, which results in a part of the rainwater loss that is not included in the calculation.This can be avoided in two ways.One is in the commissioning phase, to high rain intensity for the tune pilot and ensure that the upper and lower turning frequency is the same, so that even if the measurement results of fluctuations up and down, but also will not exceed the permissible range of error; the second is to improve the design of the flip-bucket type rain gauge, add a stopper, so that it and the measurement of the funnel with the same axis of the same turn, to achieve the measurement of the funnel when the flip blocking the throttle tube, blocking the process than the loss of rainwater.This will not only improve the accuracy of the instrument, but also reduce the error brought about by manual adjustment to a certain extent, but the processing difficulty and cost will be increased.
Typology
JD-02 type tipping bucket rain gauge
(1) Function: The core component of this instrument, the tipping bucket, adopts three-dimensional streamlined design, which makes the tipping bucket turn over water more smoothly and has the function of self-washing dust and easy cleaning.
2) Structure and characteristics
The instrument consists of rain bearing mouth, screen, integrated bracket, water diversion funnel, integrated upper tipping bucket assembly, tipping bucket, tipping bucket support, tipping angle adjusting device, level adjusting device, constant magnet, reed switch, signal output terminal, drainage funnel, base, stainless steel cylinder body, base support feet and so on.
Unlike other double tipping bucket rain gauge, the upper tipping bucket of this rain gauge is an integrated component device installed in the water diversion funnel, and its lower tipping bucket is a measuring and counting bucket.There is no need to make any adjustment to the upper tipping bucket assembly when installing and using this instrument.This type of tipping bucket rain gauge on the lower tipping bucket increased a movable diversion plate and two for changing the direction of the movable diversion plate turn limit column, in the tipping bucket turning over the process of water, the instrument's movable diversion plate at the top of the diversion of the water blade can automatically turn to the edge of the precipitation drainage column of the critical point of the location of the edge of the water when the tipping bucket water is full of water to turn over the beginning of the water, the diversion of the edge of the water immediately across the drainage column of the completion of the precipitation switching task between the two buckets.When the bucket is full and starts to turn over the water, the water-splitting edge will immediately cross the drain column to complete the waterfall switching between the two water-bearing buckets, which shortens the time of waterfall switching and reduces the measurement error.
The bucket support of this instrument is an integrated rotary positioning structure, which makes it more convenient to install and dismantle the bucket, and there is no need to adjust the distance between the two bucket supports, which brings convenience to the user for installation.The tipping bucket of this instrument is three-dimensional streamlined design, and designed with a sagging curved surface deflector tip, which has a beautiful and smooth shape, better water turning performance and easy to clean and maintain.
This instrument is equipped with two constant magnets on the hopper, reed switch bracket is equipped with two reed switches, the instrument factory magnets and reed switches have been adjusted in the appropriate coupling distance, so that the instrument output signal and the number of times the hopper is turned over to determine the proportionality of the relationship.One of the two signal outputs of the instrument is used for on-site counting and measurement, and the other one is used for telemetry.When this instrument is connected with telemetry terminal, it should be equipped with matching interface circuit to prevent counting and reporting errors caused by reed switch jitter and hopper bounce.
When this instrument is shipped from the factory, the tilting angle adjustment screw of the tipper has been locked in the best tilting angle base position and the tilting angle screw has been sealed with red paint, so the user only needs to install the tipper in the 2 tipper supports on the tipper bracket according to the relevant requirements of this manual and level the tipper bracket so that the horizontal bubble is located in the center position to be put into operation, and there is no need to adjust the tipper tilting angle on the spot again.
(3) Main technical parameters
Bearing rain caliber: φ200;
edge acute angle: 40o ~ 45 o
resolution: 0.1mm, 0.2mm, 0.5mm, 1mm optional;
Measurement accuracy: ≤ ± 3% (indoor artificial precipitation, to the instrument's own drainage shall prevail)
rainfall range: 0.01mm ~ 4mm / min (allowed to pass through the maximum rainfall strength of 8mm / min)
Sends a signal mode: double-contact on-off signal output
Working environment:
ambient temperature: 0 ~ 50 ℃
relative humidity; <95% (40 ℃)
Size and weight: φ216 × 410 2.2Kg
XYL-2 type tipping bucket rain gauge
XYL-2 type tipping bucket rain gauge has the advantages of small size, low power consumption, high precision, high reliability, integration of rainfall detection, collection and transmission It is the most accurate rain gauge in China at present.If you need an independent rainfall data recording system you can install a data logger through the relevant PC software can be extracted and analyzed rainfall data.It can be widely used in meteorology, hydrology, marine, military, airport, environment, agriculture, forestry, scientific research and other fields.
1. Rain sensor technical indicators:
Resolution: 0.2mm
Bearing caliber: Ф200 + 0.6mm
Measurement of precipitation intensity: ≤ 4mm/min
Error: (± 4%) indoor static test, rain intensity of 2mm/min
Output Signal: switch on/off signal
Measurement Parameters: the current cumulative rainfall, 50 minutes does not rain the instrument is automatically cleared, and then raining again to re-cumulative.
Operating temperature: 0℃-+50℃
Storage temperature: -10℃-50℃.
Power consumption of the whole machine: not more than 4W
Relay contact capacity: AC250V/3A
Communication: RS485 (optoelectronic isolation), adopting MODBUS-RTU protocol Maximum load of the variable output: 750 ohms
Over-limit display: "EEEEEEEE"
Operating temperature: 0℃- +50 ℃ Humidity ≤ 85RH Suitable for non-corrosive gas and dust occasions
3. System components
This tipping bucket rain gauge is composed of tipping bucket sensor and rainfall data collection terminal.The rainfall data acquisition terminal can display the rainfall data in real time can be manually placed into the data, and the combination with the GPRS transmitter can be transmitted wirelessly to the monitoring center.Tipping bucket rain sensor consists of water bearing mouth, filter, upper cylinder, connecting screw, magnet, dry reed switch, lower cylinder, leveling bubble, leveling screw and so on.
4. Principle of operation
Tipping bucket rain sensor is a mechanical bistable structure, when a bucket room to receive water, the other bucket room is in a waiting state, when the received rainwater volume reaches a predetermined value, due to the effect of gravity itself toppled over, in a waiting state.The rainfall data collection terminal receives the signal and displays it.
