OPERATING INSTRUCTIONS Automatic Rain Gauge 1518-H3

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1 Features Rain gauge for automatic weather stations Tipping bucket acc. to Joss-Tognini Exchangable without calibration Low surface adhesion Reproducible intensity curve Full winter-usable with electronic heating device High service life Only weathering materials are used (anodized aluminium, stainless steel) Funnel according to the WMO Standard Function The automatic rain gauge 1518 H3 registers precipitation falling with a tipping bucket according to Joss-Tognini. This bucket has a reproducible intensity curve and can be exchanged without a new calibration of the rain gauge. The volume of the bucket is 2 cm³. Referring to the receiving surface of 200 cm² (WMO-Norm) a bucket capacity correspond to 0.1 mm precipitation per square meter. Each tip of the bucket closes the circuit of a reed switch for minimum 65 ms. This impulse can be registered electronically. The reed contact filled with mercury is shut hermetically. It has a high life time, a good reliability and a high reproducible contact velocity. The sensor 1518 H3 is equipped with a heating device and works at ambient temperatures down to -25 C. The heating has two heating circuits and is regulated electronically, that normally the rain gauge is free from snow and ice and the evaporations at the heating surfaces are minimized. The rain gauge is designed according to the standards of the WORLD METEOROLOGICAL ORGANIZATION (WMO). Technical Data Measuring system: Tipping bucket according to Joss-Tognini with reed-contact (closer) Reed-contact max. load: 50 V; 0,5 A; 12 VA Contact impulse: 60 to 85 ms Bucket capacity: 2 cm 3 Receiving surface: 200 cm 2 (WMO Standard) Resolution: 1 tip ~ 0,1 mm of precipitation Operating range: 0...7,5 mm of precipitation / min General Dimensions: Height: 494 mm; Outer-Ø: 224 mm; Ø of the mounting socket: 60 mm 7 kg Weight: Heating Heating type: Elektronical resistance heating 2 heating circuits Power supply: 42 V AC Heating capacity: Top ring 100 VA receiving funnel 100 VA drainpipe/bucket 35 VA Overall 235 VA Operating temp. range: down to -25 C OPERATING INSTRUCTIONS Automatic Rain Gauge 1518-H3

2 Overview ring heating funnel heating receiving funnel temperature sensor tipping bucket drain pipe drain pipe heating waterproof MIL connector 2

3 Installation The precipitation gauge is fixed on a base plate with pipe connections, which is set up simply onto a tube with an outer diameter of 60 mm. Fixing occurs via 2 x 3 hex-socket set screws, those are placed in the angle of 120 to each other. If a wood pile is used, we recommend to slip a metal pipe on at the end of at least 100 mm length and then to set up the precipitation gauge. Assembly of the sensor The rain gauge must be fitted so that the upper measuring edge D (see fig. 1) is aligned horizontally. This is essential to ensure a troublefree operation of the tipping bucket. When the rain gauge is mounted on the fastening tube up to the collar, carefully place a spirit level on the upper edge of the measuring ring to make adjustements. The precipitation gauge is aligned vertically by means of the three screws A. Then the screws B are uniformly tightened. With dismantled casing C it is possible to make the leveling with a circular spirit level which is mounted on the plane surface of the base plate. Assembly of the Tipping bucket To avoid damage to the tipping bucket during transport, it is separately packed and should be inserted in the rain gauge on site only after mounting the gauge on the steel tube. For the assembly first you must remove the protective jacket. Remove of the protective jacket Opened the two tension locks F and G. Then the protective jacket C can easily be bent asunder and removed over the measuring ring D. Then the interior of the sensor 1518 H3 is easily accessible. Inserting the tipping bucket When fitting the tipping bucket, proceed with utmost caution so that the sharp edges of the tipping bucket are not damaged and the middle wall is not bent! In operation the tipping bucket layed on the tipping bucket bearing. To reduce the frictional, which are produced at one tipping, the bearings A (fig. 2) are made off Teflon. Fig. 2 A Teflon bearing B Fixed locking plate C Slidable locking plate D Reed contact E Circular spirit level Fig. 1 To insert the tipping bucket, first the slidable locking plate C (fig. 2) must be pushed back. Now insert the tipping bucket. Make sure that the magnet attached to the middle wall of the tipping bucket rests under the bush with the embedded reed contact D. Finally the tipping bucket must be secured by pushing back the slidable locking plate. 3

4 Electrical connections Over a 7 pole plug connector at the bottom of the base plate the sensor will be electrical connected. We recommend the following cables: 1. Between precipitation gauge and heating transformator 1518 T: LiYY-LiYCY 2+2x0,5² cable. The shielded cores of this cable are used as signal lines, the unshielded cores are used for the power supply of the heating device. 2. Between the heating transformator 1518 T and the data aquisition system: 2 x AWG 20 CUL sw cable. Attention! The shield of the data line must be exist over the whole length. 3. For the connection of the 230 V AC power supply to the heating transformator, we recommend: NYY-J 3x1,5² cable. The sensor and the heating transformator must be connected according the circuit diagram. In the following table you find the maximum cable length in dependence of the cable cross-section. Electrical Wiring cable cross-section (Cu-Cores [mm²] max. length [m] TIP 1 When the cable is transferred inside the soil it is recommend to protect the cable with a protecting plastic tube. TIP 2 Generally, when registrating measured data, attention must be paid to the fact that the sensor pulses are not bounce-free. This means that a data acquisition system must be equipped with a debouncing circuit on the input-side. The limit data for contact loading must be observed. In cas of inductive loads (e.g. magnetic pulses) on the reed contact, it must be protected from induction voltages by fitting a diode or a resistor/capacitor network. It is recommended that a resistor of 50 to 100 ohms be soldered in series with the contact, if the data acquisition system brought in by the reed contact permits it. This protects the contact from current peaks which occur primarily as a result of capacitive loads (e.g. on long cables). Wiring diagram of the 1518hH H3 pin assignment (from the solder side) Wiring diagram of the heating transformator 1518 T 4

5 Putting into operation The precipitation gauge 1518-H3 is completely produced at the factory. After the assembly and the connection of the electrical, the sensor will be in operation immediately. Only a function check should be done. Function check The function check of the rain gauge can be carried out with artificial precipitation. The contents of a testing vessel with 200 cm³ water is to be run through a nozzle into the collecting funnel so that the drops fall into the funnel beside the drain. The diameter of the nozzle should be approximately 0.6 mm so that the amount of water can be drained off in 10 to 20 minutes. Due to the high intensity of this artificial rain, a desired value is given for the number of tipping bucket tilting operations depending upon the run times of the test fluid through the system. This desired value can be seen from the following diagram: y-axis: Desired value for the number of tipping bucket tilting operations Maintenance In order to ensure the function of the precipitation sensor 1518 H3, it should be checked and cleaned at regular intervals, since dirt can lead to measurement deviations. Cleaning Clinging particles of dirt in the collecting funnel or outlet pipe may be removed with a piece of wood. If unsatisfying measurement results occur after this cleaning procedure, the rocker should be disassembled for cleaning. Absolute care must be taken not to damage the rocker! The dismounted rocker can be cleaned by placing it in warm water with some scouring material and by carefully scraping off unwanted dirt using a small piece of wood. Dimensional Drawing x-axis: Run time in minutes Heating device The adjustment of the control range of the proportional position action to the nominal value 1 to 4 C is already done in the factory and no readjustment is required during operation. In case of ambient temperatures below 4 C it is possible to control the operation of both heating circuits with the two light emitting diodes (LED) in the opened controller housing. At ambient temperatures above 4 C the operation of the heating device can be only be controlled if the rain gauge is opened. By cooling the measuring sensors of the heating control system (measuring sensors are located at the measuring ring and at the collecting funnel) with a cold spray, it is possible to simulate temporarily low temperatures. 5

6 Ordering text Specification Ordering number Automatic Rain Gauge 1518-H3 Bucket-measuring system with Reed-contact (closer) and electronical heating; power supply: 42 V AC; WMO- Standard; with funnel spiral; operating temperature range: down to -25 C; for mast mounting with 60mm Ø; Mast for 1518-H3; needs a concrete foundation Heating transformer 1518 T for the power supply of the 1518-h3 heating with distributor; Power supply: 230 V AC; output voltage: 42 V AC, 250 VA Holder Mounting support for 1518 T Connection cable with connector Connection cable, 7 m LiYY-LiYCY 2+2x0,5² cable; 0,6 m long; for the connection of the 1518-H3 with the 1518 T 2xAWG 20 CUL sw (0,56²); 7 m long; connects 1518 T with the data acquisition system Connection cable, 11 m 2xAWG 20 CUL sw (0,56²); 11 m long; connects 1518 T with the data acquisition system Ring against birds prevent that birds are landing on the rain gauge Spare funnel spiral protects the tipping bucket against dirt Quality has tradition since Reg.No Vers Technical alterations reserved. WORLDWIDE TO BE PRECISE! Sensors Hand-held Instruments Stationary Equipment Telemetry Devices System Techniques for Meteorology, Industry and Environmental Protection Represented in 62 countries Wilh. Lambrecht GmbH Friedländer Weg D Göttingen P.O.Box 2654 D Göttingen Telephone +49-(0) Telefax +49-(0) sales@lambrecht-online.com