CCSCM
Czech Calibration Station of Current Meters

Equipment of CCSCM

Premises

Basic premises of CCSCM are the calibration tank, control room and a hinterland with switching station from where all sluice gates are controlled.

Big Experimental Tank

The big experimental tank was built in the framework of construction of the building of former State Research Institutes of Hydrology and Water Structures and it was put into operation in 1930. The tank is fed by water from the navigational canal of the Troja weir and it passes through the area of the T. G. Masaryk Water Research Institute (TGM WRI) in a north-south direction. It has total length of 248.9 m and bottom slope. It consists of intake, equalizing part with a double sided weir for keeping the water level constant, calibration tank proper, outflow part (measuring tank) and outlet into the canal.

Intake part of the tank is situated in front (southern) part of TGM WRI area and is determined by the intake construction situated in the bay of the navigational canal in the area of upper raids of double lane one-chamber lock Troja-Podbaba and by the sluice gate I.

Equalizing part of the tank is also situated in front (southern) part of TGM WRI area and is determined by the section between sluice gate I and sluice gate II. This part of tank is equipped with two fixed overflow edges (each 25 m long) providing a stable level in a calibration part of the tank. Excess water is diverted by a separate sewer to the bottom raids of the lock. Overflow channels are on top of the normal water level of 180.10 m above sea level (altitude compensation system Baltic = Adriatic - 40 cm). Upper level of water at an elevation of 180.20 m above sea level is maintained on the Troja weir, permitted tolerances are +20 cm and -10 cm.

Calibration part of the tank is situated on the ground floor of buildings A, C and E situated in TGM WRI area and is determined by the section between sluice gate II and sluice gate III.

Outflow part of the tank (measuring tank) is situated in the back (northern) part of TGM WRI area and is determined by the section between sluice gate III and sluice gate IV. Measuring tank has length of 29 m, width of 5 m and depth of 5 m, so the total volume is 725 cubic meters.

Outlet part of the tank leads into the lower raids of the lock and is determined by the section between sluice gate IV and the outlet construction situated on the bank of navigational canal in the area of bottom raids of the lock.

All sluice gates can be operated from the switching station of the tank as well as locally, in case of emergency even by hand.

Calibration Tank

Calibration part of the tank (calibration tank) is determined by the section between sluice gate II and sluice gate III, between which the mutual distance is of 164 m. It has vertical walls, constant width of 2.5 m, average depth of2.1 m and bottom in a slight slope of 0,4 per mille. In compliance with ISO 3455 the tank is the straight open tank with volume of cca 861 cubic meters.

Calibration Tank Premises

Hinterland with Switching Station

Working section of the calibration tank has the length of 138.6 m and water depth of 1.8 m. In compliance with ISO 3455, this part of experimental tank comprises accelerating, stabilizing, measuring and braking sections.

In this section the electric self-propelled rating carriage moves along the track in a speed range of 0.02 to 7 m/s. This space is an indoor one and can be heated. Along the tank, a rail track is laid for the rating carriage. The power to the carriage is fed by a three-phase trailing wire track system situated at the right side of the tank under its ceiling. A distance gauge is located at the same place. The working section of the flume is equipped by a CCTV for visual control of the carriage function during calibrations under remote control. At the beginning of the working section, a landing, used for carriage maintenance, current meters installation and other common activities, is situated. Within the framework of building adaptations after the 2002 flood, the tank was equipped by a device enabling evacuation of the carriage (which is the most valuable part of the equipment) to the Institute’s boiler room roof in a case of flood threat.

The control room was after the 2002 flood moved one floor above the tank from its original place beside the tank to the first floor.

Control Room

Images Captured and Transmitted by CCTV

In the control room, a central computer, used for fully automated operation as well as data acquisition, their evaluation and archiving, is located. The monitor of CCTV is also situated here – the activity in the tank surrounding is monitored by 4 cameras.

Rating Carriage

The contemporary rating carriage was made by the DICONT a.s., a small Czech joint-stock company, and put into regular operation in January 2005. The carriage has electric propulsion, the power is fed by a trailing wire track system of the tank and the carriage moves on a rail track which is laid along the working section of the tank. The carriage controlling unit enables to choose arbitrary speed of the carriage movement in an interval of 0.02 to 10 m/s (the maximum speed is currently limited to 7 m/s) at both directions. The carriage has three holders for calibration of current meters suspended on rods and a winch for calibration of current meters suspended on rope with sinker weights up to 100 kg. The holders automatically turn the meters around when the direction of the carriage movement is changed. The carriage can be operated either manually from the carriage console or remotely from the control room. It is possible to input all parameters of the fully automated operation from the control room. The fully automated operation is used only for rod suspended calibration, in case of cable suspended calibration there must be an operator on the carriage. The control computer is an industrial computer of the PC class and carriage movement control is based on a custom program which was supplied by the DICONT a.s. together with the carriage.

Rating Carriage

Trailing Wire Track System and Distance Gauge

Operating Console of Rating Carriage

The Part for Mounting the Calibrated Devices

After uniform movement of the carriage is reached, the control computer starts a data acquisition. The first impulse from every meter switches the appropriate distance, time and impulse counters on. When the predetermined impulse count from the meter is reached, the counters are switched off and the data are sent to the central computer for a consecutive processing. The time is derived from the computer crystal oscillator. The distance is determined from the number of impulses caused by optical-electronic system moving along the distance gauge – a metal strip with slits at mutual distance of 0.10 m. In between the slits, the distance is interpolated on a basis of optoelectronic sensing of angular division of shafts of the driving electric motors. Measurements of the distance and the time are metrologically traced to the main standards of accredited laboratories. Acquired data are transmitted from control unit of the carriage to central computer in the control room and then processed by calibration evaluation program.

The rating carriage can be used not only for current meters calibrations, but also for experiments with towing bodies in still water, e.g. for determination of hydrodynamic resistances of ship hulls etc.

Hardware and Sofrtware

Hardware and Software

Hardware

The control computer of the carriage as well as the central computer in the control room, they are both of the PC class. They are interconnected by a Wi-Fi LAN, have no access to Internet and are protected by antivirus.

Software

Software for operation control, data acquisition and their processing is a custom one on the MS Windows platform. The software is divided into two parts, which cooperate with each other.

The first one is rating carriage control program (VELÍN), which controls the carriage operation according to predetermined parameters and also controls data acquisition. This part was supplied by the DICONT a.s. as a part of the carriage delivery.

The second one is calibration evaluation program (VRTULE), which provides processing of the calibration data up to the form of the Calibration Certificate. This part was programmed according to our demands by the Roman Škára - Software & Hardware company. This one allows to enter and to edit the identification and calibration data, to monitor the status of the calibration process (speed and position of the carriage) and data processing.

CCSCMCzech Calibration Station of Current Meters

Equipment of CCSCM

Premises

Premises

Big Experimental Tank

Calibration Tank

CCSCM
Czech Calibration Station of Current Meters