Presentation on the topic: Current Measuring Instruments
Find spiders with ammeters
To analyze energy consumption with ammeters, you must first measure all devices that work around the clock, for example, a refrigerator or freezer, where you must measure more than a day to get decent values. It may also make sense to measure the refrigerator once in the summer, and sometimes in the winter, because the outside temperature also plays a role.
In washing machines or dishwashers, you can measure in various programs: for example, it shows how many kilowatt hours you use if you wash clothes in a short program. A longer measurement is less important for devices that work so irregularly because consumption-per-use is actually interesting.
In devices such as televisions, computers, etc. It is worth measuring standby power consumption. So, you see how much energy is required here, even if the device is not working. Even if it may not seem very similar at first glance: with several devices and extrapolated for a whole year, it also adds!
Borrow or buy an electricity meter?
Electric meters can often be borrowed, sometimes even for free. Just ask your nearest consumer center or local electricity supplier. For a good average, you need to be careful not to measure too short, especially for multimedia devices. There should be a realistic combination of waiting time and usage over a period. Because if you keep the measurement in mind all the time, it is easy to change your usage habits unconsciously.
This is how you expose yourself to security forces
Detective work is required when you discover strong beasts. Saving energy works best when you know how much energy your own family consumes. Take a look at your last energy bill and compare it with similar households. Are you above average? Then it's time to find secret sources of energy. By the way: even if your consumption is below average, there are always ways to reduce it even more.
Using a power meter, you can control the energy consumption of almost all household electrical appliances: a refrigerator, washing machine, computer, TV or even an aquarium. However, only devices hanging on the network through a plug can be tested. You cannot check the boiler or electric stove.
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Presentation on the topic: Current Measuring Instruments
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Read the current counter, here is how it works
The actual measurement is very simple. You only need to unplug the power plug from the outlet. Connect the meter between the electrical outlet and the device under test so that the current flowing through it is measured as soon as you turn on the appliance. The display shows how much energy is currently being consumed. In watts, kilowatt hours, and amplifiers.
Depending on the device, you can also directly display your energy costs. Before measuring, set your price for electricity, it will recalculate the electricity used and show the amount you pay. Some gauges can even distinguish between day and night electricity rates and extrapolate them to annual consumption. Modern power meters can transmit this data by radio to a computer. To make the cost forecast realistic, you must be patient: let the measurement continue for at least a week.
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Electrical appliances - a class of devices used to measure various electrical quantities. The orienting effect of a magnetic field on a circuit with current is used in electrical measuring instruments of a magnetic-electric system - ammeters, voltmeters, etc.
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The bottom line: when is it an energy eater?
You will get a good comparison if you look at yourself. Maybe you found out that your 15-year-old refrigerator needs a little less than 600 kilowatt-hours of electricity per year? Modern, however, only 150 kilowatt hours per year? Due to its significantly lower energy consumption, the new device can pay for itself in a few years.
How to calculate electricity consumption
With a little math, you can calculate your hourly, daily or annual consumption for individual consumers. However, the following formula is not suitable for appliances that do not require full power. Their example heats water only occasionally. Product performance specifications can be found on the nameplate.
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Classification of electrical appliances Ammeter - for measuring the strength of electric current Voltmeter - for measuring electric voltage Frequency meter - for measuring the frequency of fluctuations of electric current Ohmmeter - for measuring Electrical resistance Wattmeter - for measuring electric current power Multimeters (aka testers, avometers) - combined instruments Electric meters - for measuring energy consumption
In addition, you should also check the standby consumption of your devices. Start with devices that frequently or constantly work. Quickly located over 100 euros. How to save these unnecessary expenses with a simple trick and get a small bonus in the household? One prevents standby losses.
You do not have to spend 40 euros on the top device. In addition, the results are evaluated by most lenders and thus expose your strong fans. Our listing is an ammeter that compares at least five models. A simple test of the current meter with the winner of the test of the ammeter you will not find us, because we approve of the comparison of the price of the ammeter. For example, here you can see the differences between expensive and cheap products.
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A voltmeter is a device for measuring voltage in a section of an electrical circuit. To reduce the effect of the included voltmeter on the circuit mode, it should have a large input resistance. Classification According to the principle of operation, voltmeters are divided into: electromechanical - magnetoelectric, electromagnetic, electrodynamic, electrostatic, rectifying, thermoelectric; electronic - analog and digital Intended use: DC; alternating current; impulse; phase sensitive; selective; universal By design and method of application: switchboards; portable; stationary Magnetoelectric, electromagnetic, electrodynamic and electrostatic voltmeters are measuring mechanisms of the corresponding types with indicating devices.
How to find out the real test of an ammeter?
The Internet is full of the obvious winner of the power meter test, so you can hardly tell the difference between true and false content. Anyone who has a product in their hands can, of course, choose a personal ampere counter and win a test and share their experience. However, a real test of a power meter should contain several subjective impressions, but prove priceless. Therefore, in the end, only a certified winner of these experts matters, especially since many people buy their results.
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Ammeter - a device for measuring amperage. In the electric circuit, the ammeter is connected in series with that section of the electric circuit in which the current is measured; to increase the measuring range - with a shunt or through a transformer. Ammeters are magnetoelectric, electromagnetic, electrodynamic, thermal, induction, detector, thermoelectric and photoelectric. Magnetoelectric ammeters measure the strength of direct current; induction and detector - AC power; ammeters of other systems measure the strength of any current. The most accurate and sensitive are magnetoelectric and electrodynamic ammeters.
Of course, other sources can also do a good ammeter test if there are some obvious evaluation criteria. Follow the winners of the tests of real power meters if you want to report about yourself. We recommend that you carefully read our product guides to find out all the pros and cons. Our power meter buying guide serves as the basis for buying the best power meter, depending on your taste. The more purchase criteria for quality control applied to the product you are aiming for, the sooner you will get the quality of a power meter test winner.
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Ohm tr is a direct reference measuring device for determining electrical active (ohmic) resistances. Typically, the measurement is made with direct current, however, in some electronic ohmmeters it is possible to use alternating current. Varieties of ohmmeters: megaohmmeters, gigaohmmeters, teraohmmeters, milliomometers, microohmmeters, differing in ranges of measured resistances. The magnetoelectric ohmmeter is based on measuring the current flowing through the measured resistance at a constant voltage of the power source. To measure resistances from hundreds of ohms to several megaohms, the meter and the measured resistance are connected in series.
For each product presented, we establish individual evaluation criteria. In the end, you even decide in practice to test the ampoule in place, whether you buy the winner of the power meter test! Electrical measurements are methods, devices, and calculations used to measure electrical quantities. The measurement of electrical quantities can be performed by measuring the electrical parameters of the system. Using transducers, physical properties such as temperature, pressure, flow, force, and many others can be converted into electrical signals that can be conveniently recorded and measured. Thus, they are called electricity meters for all devices that are used to measure electrical quantities and thus ensure the proper functioning of electrical installations and machines. Most of them are portable portable devices and are used for assembly; There are other tools that are measuring transducers and other methods for measuring, analyzing and analyzing. Data acquisition is becoming increasingly important in the industrial, professional and private fields. This is a tool used to detect and measure electric current. This is an electromechanical analog converter that deforms rotation with a needle or pointer in response to an electric current flowing through its coil. The term has been expanded to include the use of the same device in recording equipment, positioning and servomechanisms. This consists of a usually rectangular coil through which the measured current circulates; this coil is suspended inside the magnetic field associated with the permanent magnet in accordance with its vertical axis so that the angle of rotation of the coil is proportional to the current passing through it. This is a tool that is used to measure the intensity of current circulating in an electric circuit. In general, an ammeter is a simple galvanometer with parallel resistance, called “shunt resistance”. With a range of shunt resistors, an ammeter with several ranges or measurement intervals can be obtained. Ammeters have a very small internal resistance of less than 1 Ohm, so that their presence does not reduce the current that must be measured when connected to an electrical circuit. This is a tool used to measure the potential difference between two points of an electrical circuit. To measure the potential difference, the voltmeter should be located in parallel; those. when derivating at points between which we are trying to measure. This leads us to the fact that the voltmeter must have the highest possible internal resistance so that it does not cause a noticeable flow rate, which would lead to an erroneous voltage measurement. Currently, there are digital devices that perform the function of a voltmeter with fairly high insulation characteristics using complex insulation schemes. This is an electrodynamic device for measuring electrical power or the rate of supply of electricity in a given electrical circuit. The device consists of a pair of fixed coils called “current coils” and a mobile coil called “potential coil”. Fixed coils are connected in series with the circuit, and mobile coils are connected in parallel. In addition, in analogue wattmeters, the voice coil has a needle that moves on a scale to indicate the measured power. The current flowing through the fixed coils generates an electromagnetic field whose power is proportional to the current and is in phase with it. As a rule, a mobile coil has a large resistance connected in series in order to reduce the current flowing through it. This is a device for measuring power factor. It has an internal voltage and a current coil located in such a way that if there is no phase shift, then the needle has a zero value, which is measured by the Cosimeter - this is the phase shift that occurs between the current and the voltage product of inductive or capacitive loads. This is a hand tool designed for detecting the scope of three-phase systems. There are two types: one based on a very small three-phase motor that just rotates in one or the other direction, so you know if the sequence goes left or right, depending on how you connected the phases to it. Another type is based on neon bulbs and a passive circuit in which the phenomenon of capacitive components is used to advance or delay the phase angle and is thus known by igniting one or the other pilot sequence. Remember that each phase is a sine wave, which is 120 degrees out of phase with respect to the other two. This is a tool used to measure frequency, counting the number of wave repetitions in the same position over a period of time, using a counter that accumulates the number of periods. Since the frequency is defined as the number of events of a particular class occurring over a period, its measurement is usually simple. According to the international system, the result is measured in Hertz. The read value is displayed and the counter is set to zero to begin accumulating the next sampling period. This is an electronic measuring device for graphically presenting electrical signals that can change over time. It is widely used in signal electronics, often together with a spectrum analyzer. The image thus obtained is called an oscillogram. Also called the Wheatstone Bridge, it is used to measure unknown resistances by balancing the arms of the bridge. They consist of four resistors that form a closed loop, one of which is the resistance when measuring. In addition, they can be used to measure impedance, capacitance, and inductance. The location of the bridge is also widely used in electronic devices. To do this, one or more resistors are replaced by sensors, which, when their resistance changes, cause an output proportional to the change. Let the other always be ready to accept the sweet accents of the voice of your heavenly friend Andre-Marie Ampère. A measuring device is a device that is used to compare physical quantities through a measurement process.
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Wattme tr is a measuring device designed to determine the power of an electric current or an electromagnetic signal. By purpose and frequency range, wattmeters can be divided into three categories - low-frequency (and direct current), radio-frequency and optical. Wattmeters of the radio range for their intended purpose are divided into two types: transmitted power included in the break of the transmission line, and absorbed power connected to the end of the line as a coordinated load. Depending on the method of functional transformation of the measurement information and its output to the operator, the wattmeters are analog (showing and recording) and digital.
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Frequency meter - a measuring device for determining the frequency of a batch process or the frequencies of the harmonic components of the signal spectrum. Electronic counting frequency meters (ESCs) are the most common type of frequency meters due to their versatility, a wide range of frequencies (from fractions of a hertz to tens of megahertz) and high accuracy. To increase the range to hundreds of megahertz - tens of gigahertz, additional units are used - frequency dividers and frequency carriers. In addition to the frequency, most ESCs allow measuring the pulse repetition period, time intervals between pulses, the ratio of two frequencies, and can also be used as counters of the number of pulses.
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Multimer is a measuring device that combines several functions. In the minimum set, this is a voltmeter, ammeter and ohmmeter. There are digital and analog multimeters. Functions are also available in some multimeters: Calling - measurement of electrical resistance by sound (sometimes light) signaling of low circuit resistance. Generation of a test signal of the simplest form (harmonic or pulsed) - as a kind of dialing option. Diode test - checking the integrity of semiconductor diodes and finding their "forward voltage". Transistor Test - Testing Semiconductor Transistors Measuring Electrical Capacitance. Inductance Measurement. Temperature measurement using an external sensor. Measuring the frequency of a harmonic signal.
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Electric energy meter (electric meter) - a device for measuring the flow of electricity of alternating or direct current. By the type of connection, all the meters are divided into devices for direct connection to the power circuit and transformer devices connected to the power circuit through special measuring transformers. According to the measured values, electric meters are divided into single-phase (measuring AC 220V, 50Hz) and three-phase (380V, 50Hz). All modern electronic three-phase meters support single-phase metering. By design: An induction electric meter in which the magnetic field of the stationary conductive coils affects a movable element of conductive material. An electronic electric meter in which alternating current and voltage act on solid-state elements to create pulses at the output, the number of which is proportional to the measured active energy. . Hybrid electricity meters are a rarely used intermediate version with a digital interface, a measuring part of an induction or electronic type, and a mechanical computing device.
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The measuring device of the magnetoelectric system is arranged as follows. Take a lightweight aluminum frame 2 of a rectangular shape, wrap a coil of thin wire on it. The frame is mounted on two axes O and O ", to which the arrow of the device is also attached 4. The axis is held by two thin coil springs 3. The elastic forces of the springs, returning the frame to the equilibrium position in the absence of current, are selected so that they are proportional to the angle of the arrow from the position equilibrium: The coil is placed between the poles of the permanent magnet M with the tips of the shape of a hollow cylinder.The inside of the coil is a soft iron cylinder 1. This design provides a radial direction of the magnetic lines in the region of finding the coil turns (see figure). As a result, for any position of the coil, the forces acting on it from the side of the magnetic field are maximum and are constant at a constant current strength. Device devices of the magnetoelectric system
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As a result, for any position of the coil, the forces acting on it from the side of the magnetic field are maximum and are constant with a constant current strength. Vectors F and –F represent the forces acting on the coil from the side of the magnetic field and turning it. The coil with the current rotates until the elastic forces from the side of the spring balance the forces acting on the frame from the side of the magnetic field. Increasing the current strength in the frame by 2 times, the frame will rotate an angle twice as large. This is because Fm ~ I. The forces acting on the frame with the current are directly proportional to the current strength, that is, by calibrating the device, it is possible to measure the current strength in the frame. In the same way, the device can be configured to measure the voltage in the circuit if the scale is calibrated in volts, and the resistance of the frame with the current must be chosen very large compared to the resistance of the section of the circuit on which we measure the voltage.
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References Myakishev, G.Ya. Physics: Textbook. for 11 cl. general education. institutions / G.Ya. Myakishev, B.B. Bukhovtsev. - 12th ed. - M.: Enlightenment. 2004. - from 14 - 15 Measuring equipment. [Electronic resource] - Access mode: - http://www.electrovymir.com.ua Electrical meters. [Electronic resource] - Access mode: - http://ru.wikipedia.org/wiki
Current measurement. Instruments designed to measure current are called ammeters. Devices considered in Sec. 9, can serve both for measuring current and for measuring voltage. In this case, the methods of their inclusion in the electric circuit and the resistance values \u200b\u200bof the measuring circuit of the device differ. The ammeter is included in the circuit so that the entire measured current passes through it, i.e., in series. The resistance of the ammeter should be small so that there is no noticeable voltage drop in it.
Amperemeters of the magnetoelectric system and, less often, instruments of the electromagnetic system are used for measuring direct current, and ammeters of the electromagnetic system are mainly used for measuring alternating current with a frequency of 50 Hz.
The direct inclusion of an ammeter in the circuit of the measured current is not always possible, since in some cases the measured current is many times higher than that necessary for the complete deviation of the mobile system of the device. In these cases, when measuring direct current, a shunt is inserted parallel to the ammeter, through which a large part of the measured current passes (Fig. 10.1).
According to the first Kirchhoff law, the maximum value of the current measured by an ammeter in the presence of a shunt
where I max - the maximum value of the current in the circuit; I An - nominal (limit) value of the current of the ammeter in the absence of a shunt; I w - current passing through the shunt. Since the ammeter and the shunt are connected in parallel, the currents between the shunt and the ammeter are distributed inversely in proportion to their resistances:
where do we find the resistance of the shunt:
where r A - internal resistance of the ammeter; n \u003d I max / I An - coefficient showing how many times the measurement limits expand.
As 
then the current in the circuit at a given load
where I A - reading of the ammeter. If the ammeter scale is calibrated taking into account the shunt, then it is possible to determine the value of the measured current I directly from the readings of the device.
When measuring alternating currents, shunts are not used. This is because the distribution of currents between the shunt and the ammeter is determined not only by their active resistance, but also by the reactance of the device, which depends on the frequency. Therefore, to expand the limits of measurement of ammeters in AC circuits, measuring current transformers are used.
Voltage measurement. Electrical appliances designed to measure voltage are called voltmeters. Voltmeters include parallel to the section (element) of the electrical circuit, which measure the voltage. In this case, the voltmeter must have a very large resistance compared to the resistance of the circuit element on which the voltage is measured. This is necessary to reduce the measurement error and so that there is no change in the operating mode of the circuit. In fact, the greater the resistance of the voltmeter, the less current passes through it and the less energy is consumed in it, and therefore, the less influence the inclusion of the device has on the mode of operation of the circuit.
To expand the measurement range of voltmeters in DC circuits with voltages up to 1000-4500 V, additional resistors are used, connected in series with the device (Fig. 10.2). In AC circuits with voltages above 1000 V, voltage transformers are used to expand the limits of measurement.
When an additional resistor is connected in series with a voltmeter, the resistance of the latter is determined from the following considerations: for example, with a resistance voltmeter r V rated voltage U nom , it is necessary to measure the voltage U xmax which is n times larger U nom . In this case, it is necessary to observe the condition under which the current passing through the voltmeter would be the same at both voltages, i.e.
(10.3)
and actually measured voltage
where U V - voltmeter reading.
The scale of voltmeters in most cases is graduated taking into account the additional resistance r d . In this case, the voltmeter can be performed over several measurement limits, for which it is equipped with several additional resistances and the corresponding scale switch on the front side of the device.
To measure voltage in direct current circuits, magnetoelectric voltmeters are used, and in alternating current circuits, electromagnetic and electrodynamic voltmeters are used. When measuring small alternating voltages, rectifier and electronic millivoltmeters are used, and at higher frequencies, mainly electronic.