Ammeter design dc metering circuits electronics textbook. How to measure current with an analogue multimeter. Valeports latest electronics architecture allows multiple additional sensors, and a variety of communications options, making it one of the few multiparameter current meters that allows real time operations over several thousand metres of cable, as well autonomous deployments. The ta will show you how to use a protoboard, also known as breadboard, and the dc power supplies. A metallic horizontal stick can be interlocked in the dipping bar to counterbalance the force of the flow. Use ofcurrent meters for continuous measurement offlows in.
In principle the working of the two types is based on the same theory and can be outlined as mentioned below. The dipping bar tauchstab can be used to measure the flow velocity based on the torque exerted on the bar by the streamflow. Adc ott acoustic digital current meter insruction manual. Most of these studies were published before 1960, prior to the. Total circuit current must then flow through the meter. The currentmeter with conical cups is more popular because of its accuracy and efficient working.
Float method for measuring flow rate with video iei. The velocity of flow at any point in the open channel can be most accurately and conveniently determined by means of a mechanical device named currentmeter. In general, mphase power can be measured by means of m 1 wattmeters. A meter designed to measure electrical current is popularly called an ammeter because the unit of measurement is amps.
Mechanical current meters are mostly based on counting the rotations of a propeller and are thus rotor current meters. First, methods making use of velocity measurements are applied. Power meters shall possess the following attributes 96 1 crest factor. The protoboard the protoboard allows you to assemble circuits by placing components into the. This power conversion is what provides the voltage signal. However, a variety of advanced equipment can also be used to sense stage and measure streamflow.
In contrast to a multimeter, the clamp meter does not need to be connected to the circuit in order to read current. The second method of damping used in most meter movements is an airtight chamber. Moving boat method discharge measurement of large alluvial rivers, such as the ganga by the standard current meter method is very time consuming even the flow is low or moderate. Pdf this paper presents a rapid method for propeller current meter calibration, enabling calibration of current meters in their actual working. Here, in the picture, observer is seen measuring the depth by wading rod. A record ice jam in the sl clair river occurred in april 1984 and provide4 an excellent opportunity for testing the current meter program. The ekman current meter is a mechanical flowmeter invented by vagn walfrid ekman, a swedish oceanographer, in 1903. Measuring discharge with acoustic doppler current profilers from a moving boat contains the most current information and guidance regarding acoustic doppler current profilers adcps used by the usgs at the time of publication.
In addition, the study also examined a key piece of equipment for the study, the tracerinjection pumps, to deter. When the meter is lowered in water and when it faces the current of water in the channel the wheel rotates. High accuracy is obtainable with this method, and its use is recommended. This paper presents a rapid method for propeller current meter calibration, enabling calibration of current meters in their actual working conditions using simpler equipment than what is currently. The midsection method measurement of velocity currentmeter measures velocity at a point discharge measurements require determination of the mean velocity in each of the selected verticals mean velocity in a vertical can be approximated by making velocity observations and using a known relation between those velocities and the mean in the vertical.
Before we go into indepth explanations on how you can measure dc amps with a clamp meter, we would begin by giving a summary of the dc amp and the clamp meter, so you have an understanding of how they relate talking about electricity without mentioning current would be difficult, current is the flow of electricity through a circuit or a conductor, and it is measured in ampere. The methods conventionally used for these measurements utilize an immersed current meter in different points of a river section, which acquires the mean flow. This induced current will act to damp oscillations. The most common method used by the usgs for measuring velocity is with a current meter. The method is commonly used in initial investigations of potential mini and. The method is commonly used in initial investigations of potential mini and small hydropower sites. The resistor is a direct method of current measurement that ha s the benefit of simplicity and linearity.
Interpreting the 50 microampere scale illustration on next page the black arc that is labeled dc second from top is used for taking all dc current measurements. The development of new and improved adcps is ongoing, as are the. Some measurements obtained in indiana during the floods using the adcp would not have been possible using the conventional current meter method. The techniques used are current meters, electromagnetic devices and a. It comprises a propeller with a mechanism to record the number of revolutions, a compass and a recorder with which to record the direction, and a vane that orients the instrument so the propeller faces the current.
One of the most common methods is the use of current meters. Points method, the 2point kreps measurement, the velocity distribution method multipoint. Typical current meter method divide stream cross section into transects 815 total measure velocity in each with meter at 60% depth in shallow water standards, and techniques volume 310 watthour meter maintenance and testing internet version of this manual created december 2000 facilities engineering branch denver office denver, colorado the appearance of the internet version of this manual may differ from the original, but the contents do not. Pdf the paper presents experiences gathered during many years of utilizing the currentmeter and pressuretime methods for flow rate measurements in. The current meter is set at a position such that it measures the average velocity in the vertical see section f. Performance for electromagnetic current meters depends on the probe shape, location of the electrodes on the probe, and the construction of the meter electronics. The current meter is used to measure water velocity at predetermined points subsections along a marked line, suspended cableway, or bridge across a river or stream.
Illuminance meter removed for power measurements, after target illuminance achieved 95 h power meter. Floatation method measured 20% more flow than the acoustic meter method flowtracker 8. Introduction of ammeter as we know a word meter is associated with the measurement system. Discharge is determined by summing discharge in these subsections using the midsection method conventional current metermethod the places where depth and velocity are measured. It gets rid of the unnecessary procedure of breaking the circuit to measure current. Keystone gulch near dillon, colorado, and brandon ditch near whitewater, colorado fig. Current measurement using multimeter electronics hub. This is known as the twowattmeter method of measuring threephase power. The midas ecm is a highly versatile point current meter, designed with durability and ease of deployment in mind. The ta will show you how to use the multimeter for measuring current, voltage and resistance.
Read this article to learn about the measurement of velocity by currentmeter. National environmental monitoring standards open channel. The roberts radio current meter is a device mounted on a moored buoy and transmits its findings via radio to a servicing vessel. Traceable technique to calibrate clamp meters in ac current from 100 to 1500 a article pdf available in ieee transactions on instrumentation and measurement 619 september 2012 with 3,656 reads. Measuring stream discharge using the usgs midsection method. Pdf a calibration method of current meters researchgate. There are two basic techniques for making low current measure ments. The sixtenthsdepth method consists of measuring the velocity at 0. Pdf the comparative analysis of the currentmeter method and the. Now you see it widespread use of the internet has encouraged innovative solutions to make stream flow data available. Pdf comparison of discharge measurement by current meter and. A mid20thcentury realization is the ekman current meter which drops balls into a container to count the number of rotations. Low current measurements basic current measurements in a typical circuit see figure 1a, a source causes a current i. The water current meter offers two unique methods for determining average water velocity.
Using the tracerdilution discharge method to develop. The principle of this method is the same as for the currentmeter. Introduction to measurement methods discharge computations by. However, the method should not be used where the depth is less than 2 ft. Measuring stream discharge using the usgs midsection.
The current sense resi stor is placed in line with the current being measured and the resultant current flow causes a small amount of power to be converted into heat. Conventional current metermethod the places where depth and velocity are measured verticals define subsections of the channel cross section. From there the total power of the lines, regardless of balance of current, voltage or load variations, can be accurately derived. The manual concentrates on the current meter streamflow measurement by wading. There are a few minor differences in way that current measurements are made, but the same basic principles are used. Measurement of threephase power with the 2wattmeter. Pdf traceable technique to calibrate clamp meters in ac.
Many studies of currentmeter performance have been conducted by researchers thibodeaux, 1992. A clamp meter is a tool for measuring current on a wire. Ammeter working principle and types of ammeter electrical4u. Currentmeter of common use may be classified in two categories according to the type of revolving. Water current meter velocity stream flow measuring. Most meter movements electrostatic movements excepted are quite sensitive, giving fullscale indication at only a small fraction of a volt or an amp. Direct heating kohlrausch method the disadvantages of steadystate thermal conductivity measurement methods are the long equilibration time. Current meters, single point meter, direct reading, self.
Both ac and dc currents can be measured with a multimeter by connecting the meter in series with the circuit, in which current being measured provided the current in that circuit is limited or controlled by a load or appropriate values of resistance. The two wattmeter method measures the current in two of the three lines and two voltages from the said lines with respect to the third line. This is impractical for most tasks of voltage and current. Although not as accurate as a measuring device such as a flume or a flow probe, the float method can provide an educated estimate. This paper presents a rapid method for propeller current meter calibration, enabling calibration of current meters in their actual working conditions using simpler equipment than what is currently used in traditional calibrations, and exploiting the uniform velocity profile present through submerged outflows e.
The method is valid for both balanced and unbalanced circuits with either the load or the source unbalanced. In addition to this method of damping, which comes from the movement itself, most meters use a second method of damping. Measurement of velocity by currentmeter with diagram. A fairly simple method for measuring flow rate through an open channel is the float method.
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