Why test the inductance of a transformer s primary coil?

1. About measuring the inductance of the primary coil of the transformer: it is a means to check the quality of the transformer, and it is the same as measuring the resistance, but the method is different. Because its resistance is very small, it is not very convenient to measure, so the method of measuring inductance is adopted.

Because the primary level is high-pressure, you have to be careful.

2、[primary

coil] primary coil, the coil through which the current caused by induction in the induction coil or transformer passes, is also called a primary winding. When the primary side of the transformer applies the alternating voltage U1, and the current flowing through the primary winding is i1, the current will produce alternating magnetic flux in the iron core, so that the primary winding and the secondary winding have electromagnetic contact, according to the principle of electromagnetic induction, the alternating magnetic flux will induce electromotive force through these two windings, and its magnitude is proportional to the maximum value of the winding turns and the main magnetic flux, the voltage on the side with more winding turns is high, and the voltage on the side with fewer winding turns is low, when the secondary side of the transformer is open, that is, when the transformer is no-load, The voltage of the primary and secondary terminals is proportional to the number of turns of the primary and secondary windings, and the transformer plays the purpose of transforming the voltage.

3. Inductance: Inductance, also known as self-inductance coefficient, is a physical quantity that represents the self-inductance ability of the inductor element. When the magnetic flux passing through one coil changes, an electric potential is generated in the coil, which is a phenomenon of electromagnetic induction.

The resulting electric potential is called induced electromotive force, and the magnitude of the electromotive force is proportional to the speed of the magnetic flux change and the number of turns of the coil. The basic unit of inductance is h (h), as well as milli h, and micro hyn (uh).

4. Measuring the DC resistance of the transformer winding is a very important test item, in the "Power Equipment Test Regulations", the second order is ranked second in the transformer test project, the "Regulations" stipulate that the DC resistance of the transformer winding must be measured in the transformer handover, overhaul, minor repair, change of tap position, fault inspection and pre-test, etc., aCheck the soldering quality of wires and leads inside the winding.

b.Check whether the contact between the various positions of the tap changer is good;

c.Check whether there are any breaks in the winding or lead wire;

d.Check the correctness of the parallel branch, whether there is one or several broken wires in the winding winding formed by several parallel wires;

e.Check whether there is a short circuit between the layers and turns.

Summary. The following methods can be taken to measure the inductance coil and inductance:1

Use LCR table for measurement: Using LCR meter, connect both ends of the inductance coil to the test head to obtain the inductance and other parameters of the inductance coil. 2.

Measuring with an oscilloscope: Using an oscilloscope, connect the inductance coil to the signal source, and calculate the amount of inductance using the waveform displayed by the oscilloscope. 3.

Measuring the inductance with a frequency meter: The inductance value can be calculated by measuring the upper and lower frequencies and the center frequency with a frequency meter. Hope the above can help you!

There is a way to solve it.

Can you add, I don't quite understand it.

The following methods can be taken to measure the inductance coil and inductance:1Measure using the LCR table:

Using the LCR meter, the two ends of the inductance coil are connected to the test head, and the inductance and other parameters of the inductance coil can be obtained. 2.Measurements with an oscilloscope:

Using an oscilloscope, connect the inductor coil to the signal source, and use the waveform displayed by the oscilloscope to calculate the inductance. 3.Measuring the inductance with a frequency meter:

The inductance value can be calculated by measuring the upper and lower limit frequencies and the center frequency using a frequency meter. I hope the above review can help you!

The amount of inductance loaded with it is calculated according to the following formula: coil dissipation formula;

Impedance (ohm) = 2 * operating frequency) * inductance (mh), 360 ohm impedance is required for setting, therefore: flushing is positive.

Inductance (MH) = Impedance (ohm) (2*Operating Frequency)=360 (2*.)

From this, the number of coils can be calculated:

Number of turns = [inductance *] Circle diameter ( ).

Number of laps = [Laps.]

An AC test method is required. The resistance and inductance source are connected in series, and the current and voltage are measured by a certain alternating current. Inductive reactance of the inductor = l=2*fAlternating current frequency.

Summary. The amount of inductance can be measured by an inductance coil inductance meter. An inductance meter is an instrument used to measure the inductance of an inductor coil, which can measure the inductance of an inductor coil, as well as the resistance and capacitance of an inductance coil.

The method of using the inductance meter is to connect the probe of the inductance meter to both ends of the inductance coil, then connect the power supply of the inductance meter to the power supply, press the measurement button of the inductance meter, and the inductance meter will display the inductance of the inductance coil.

The amount of inductance can be measured by an inductance coil inductance meter. An inductance meter is an instrument used to measure the inductance of an inductor coil, which can measure the inductance of an inductor coil, as well as the resistance and capacitance of an inductance coil. The use of inductance meters is to match the inductance meter

Connect the probes of the inductance meter to both ends of the inductance coil, then connect the power supply of the split finger inductance meter to the power supply, press the measurement button of the inductance meter, and the inductance meter will display the inductance of the inductance coil.

Can you tell us more about that?

The measurement of the inductance of the inductor coil can be achieved by means of an inductance meter. An inductance meter is an instrument used to measure inductance, which can measure the magnitude of the inductance, as well as the change in inductance. When measuring the inductance of an inductor coil, the first thing to do is to make sure that the power supply of the inductance meter is correct and that the power supply voltage of the inductance meter meets the requirements.

Secondly, it is necessary to ensure that the probe of the inductance meter is in good contact with the inductance coil to ensure the accuracy of the measurement results. Finally, make sure that the inductance meter is set up correctly in order to get accurate measurement results. If there is a problem when measuring the inductance of the inductor coil, it may be caused by the power supply voltage does not meet the requirements, the probe is in poor contact with the inductor dust coil, or the incorrect inductance meter is set.

The solution to these problems is: first, to ensure that the supply voltage meets the requirements; Second, make sure that the probe is in good contact with the inductance coil; Finally, make sure that the inductance meter is set up correctly. Personal Tips:

When measuring the inductance of the inductor coil, it is necessary to ensure that the power supply voltage meets the required base, the probe is in good contact with the inductance coil, and the inductance meter is set correctly to ensure the accuracy of the measurement results.

1. DC resistance measurement method: use the resistance of the multimeter to measure the DC resistance of the antenna coil, oscillation coil, mid-circumference, and input and output transformer coils, and you can judge the quality of the search group of these inductive components. When measuring the antenna coil and oscillation coil, the range should be set to r 10 gear; When measuring the middle cycle and the output and input Huai leakage balance transformer, the range should be placed in the R 10 or R 100 gear.

2. The measured resistance value is compared with the maintenance data and the experience data accumulated in daily life, if it is very close, it means that the measured component is normal. If the resistance value is much smaller than the empirical data, it indicates that there is a local short circuit in the coil; If the gauge hand indicates that the resistance is zero, the coil is short-circuited.

3. Energizing inspection method: the power transformer can be energized to check whether the voltage of the secondary electric lead is reduced, if the secondary voltage is reduced, it is suspected that the secondary (or primary) has a local short circuit. When the transformer is quickly hot or has a burning smell or smoke after being energized, it can be judged that the transformer must have a local short circuit.

4. Instrument inspection method: you can use a high-frequency Q meter to measure the inductance and its Q value, and you can also use an inductance short-circuit meter to judge the local short-circuit phenomenon of the low-frequency coil. With a megohmmeter, the insulation resistance between the primary and secondary stages of a power transformer can be measured.

The amount of inductance is proportional to the number of turns.

The inductance is proportional to the square of the number of turns, that is to say, the inductance is proportional to the square of the number of turns, and the inductance per turn is also related to the size and quality of the core. The calculation formula is: l=(, where the coil inductance l unit:

Micro Heng, coil diameter d unit: cm, coil turns n unit: turns, wire clear mountain coil length l unit:

cm。If the number of winding turns is increased under the condition that the core remains the same, it can provide greater inductance and more abundant electrical energy, and under the condition of the same winding, the thin core has less magnetic eddy current, lower loss, and can pass through higher frequencies. However, the number of footprints is large, and the magnetic circuit is also long. Many people are looking for low internal resistance for better high-frequency response and for large inductance.

Summary. If you are not a professional single piece measurement and only have simple equipment such as a multimeter at hand, it is recommended to use the following method for indirect measurement:

The inductive reactance of the inductance coil z = 2 fl ( - pi, f--- AC frequency, l --- inductance).

The DC resistance r of the inductor coil can be measured directly with a multimeter.

Then the total impedance z total = [r 2 + (2 fl) 2] under the root number

The coil is connected to the 220 volt 50 Hz mains, and the multimeter measures the circuit current i, which is totaled by i=u z.

The total impedance z = u i (u = mains voltage 220 volts, i is measured).

Bring the data into the formula z-total = [r 2 + (2 fl) 2] under the root number

The "inductance of the inductance coil l" can be obtained

If the coil inductance is too small to be directly connected to the 220-volt mains, a small transformer can be used to step down the mains and then connect it. The actual input voltage of the coil can still be measured with a multimeter.

The magnitude of the error of the obtained inductance mainly depends on the measurement accuracy of the multimeter, and there is no problem in principle.

Measure the inductance of an inductor coil, the difference between two-wire and four-wire measurement.

If it is a non-professional single-piece measurement, and you only have simple equipment at hand such as a multimeter, it is recommended to use the following method to measure indirectly: the inductive reactance of the inductor coil z=2 fl(-pi, f---AC frequency, l---inductance) The DC resistance r of the inductor coil can be directly measured with a multimeter. Then the total impedance z total = [r 2 + (2 fl) 2] connect the coil to 220 volts 50 Hz mains, the multimeter measures the circuit current i, and the total impedance z = u z total = u i (u = mains power shortage 220 volts, volt imitation i is measured) to bring the data into the formula z total = [r 2 + (2 fl) 2] can be obtained "inductance l of the inductance coil" if the inductance of the coil is too small, can not be directly connected to the 220 volt mains, A small transformer can be used to step down the mains power and then connect it.

The actual input voltage of the coil can still be measured with a multimeter. The size of the error of the inductance obtained by Xiaofan mainly depends on the measurement accuracy of the multimeter, and there is no problem in principle.

The two-wire method is simple, that is, the resistor is connected to the general circuit The four-wire method is a bridge method with high precision.

If it's convenient, can you give me a thumbs up, thank you

Transformer Inductance:

1) The no-load inductance of the winding, also called the excitation inductance, this inductance is not linear, it will generally decrease with the increase of voltage (core saturation), the voltage-current method can be measured near the rated voltage, the measured voltage divided by the current can get the impedance (x=u i), and then the inductance can be obtained according to l=x. The effects of the DC resistance of the windings and the loss of the core are ignored here.

2) Winding mutual inductance or leakage inductance, this inductance is generally made of linear disturbance, and Pai Wu can directly short circuit the winding on the original (pay) side with voltage and current method.

The above method is only applicable to power frequency transformers, and if it is a high-frequency transformer, an AC bridge should be used to measure near the working frequency of the transformer.