What principle is used to make a clamp ammeter?

Clamp meters work the same way as transformers. The primary coil is the wire that passes through the clamp core, which is equivalent to the primary coil of a 1-turn transformer, which is a step-up transformer. The secondary coil and the ammeter for measurement form a secondary circuit.

When the wire has an alternating current passing through, it is this turn coil that generates an alternating magnetic field, which generates an induced current in the secondary circuit, and the ratio of the current to the primary current is equivalent to the inverse ratio of the number of turns of the primary and secondary coils.

A clamp ammeter is used to measure large currents, and if the current is not large enough, the number of turns of the primary wire can be increased through the clamp meter, and the measured current can be divided by the number of turns. The secondary winding of the through-center current transformer of the clamp ammeter is wound around the iron core and connected to the AC ammeter, and its primary winding is the wire to be measured through the center of the transformer. The knob is actually a range selector switch, and the role of the wrench is to open and close the movable part of the core of the core of the core of the heart-piercing transformer so that it can be clamped into the wire under test.

Hioki's CM series clamp meter adopts the clamp type ammeter designed with the principle design, including CM3291, CM4371, CM4141 and other models, which can be tested without contact from small current to high current of 4200A.

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The basic principle of the clamp ammeter is equivalent to a current transformer, and the measured wire through the jaws is equivalent to the primary side of the transformer, when there is a current on the primary side, the secondary side will induce the voltage to produce a current, and then add a variety of circuits to measure the current to form a clamp ammeter. ”

Like transformers, they are manufactured using the principle of electromagnetic induction.

Because there is a magnetic field around the current and it is proportional to the magnitude of the current, the magnitude of the current can be known by detecting the magnitude of the magnetic field. The alternating magnetic field of the alternating current can be obtained by using a coil to induce the voltage, and the fixed magnetic field generated by the DC must be obtained by a magnetic sensor (Hall element).

Clamp ammeter: An ammeter that combines a current transformer and an ammeter.

Clamp ammeter section with cautionCurrent measurements can be performed without the circuit being turned on.

The reason why there is no need to disconnect the circuit is because the clamp ammeter utilizes a meter head.

Built-in current transformer.

Picking up the current in the wire generates a current induced by the alternating magnetic field, which causes the watch hand to rotate, and the index value of the watch hand is the current in the wire. This meter does not need to be connected to the circuit.

Clamp ammeter measures current:

1. Select the appropriate clamp gauge gear and use the AC current gear.

2. Then clamp the table.

The jaws connect the clamp meter with the circuit under test.

3. Correctly connect the circuit under test, then the actual current can be detected, if you want to measure the starting current, you need to press the "inrush" button on the basis of the previous step before starting the home appliance.

Can a clamp ammeter measure DC :

1. The clamp ammeter is a special instrument for measuring alternating current. The front end of the slow-burning bright is a current transformer, which realizes the measurement task by the principle of electromagnetic induction.

2. The clamp ammeter cannot test the DC current, because the DC current has no alternating magnetic field, so the secondary current will not be generated in the clamp transformer, so the clamp ammeter cannot measure the DC current.

Precautions for the use of clamp ammeter:

1. Before use, check whether the external disturbance insulation of the clamp meter is good, whether it is damaged, whether the pointer swing is sensitive, whether the jaws are rusty, etc., and estimate the current limiting current according to the motor power to determine the range of the clamp meter.

2. The voltage of the measured conductor shall not exceed the value indicated by the clamp meter, otherwise it is easy to cause grounding accidents or potential safety hazards.

Summary. 1. The clamp meter made of electromagnetic current transformer can only measure AC current, can only accurately measure sine wave current near 50Hz, and cannot measure DC current.

2. The clamp meter made by Hall current sensor can measure AC and DC currents, and has a high bandwidth, which can measure sine wave and distortion wave currents of different frequencies.

Can a clamp meter be used to measure DC current?

1. The clamp meter made of electromagnetic current transformer can only measure AC current, can only accurately measure sine wave current near 50Hz, and cannot measure DC current. 2. The clamp meter made by Hall current sensor can measure AC and DC currents, and has a high bandwidth, which can measure sine wave and distortion wave currents of different frequencies.

Can you recommend a flexible clamp meter that can measure DC current (measuring about 2000a) to love purchasing pro.

The use of clamp ammeter: usually when measuring current with an ordinary ammeter, the circuit needs to be cut off and shut down before the ammeter can be connected to the meter for measurement, at this time, the use of a clamp ammeter is much more convenient, and the current can be measured without cutting off the circuit.

The working principle of the clamp ammeter: the circuit wire under test passing through the core becomes the primary coil of the current mutual detector, in which the current is induced in the secondary coil. So that the ammeter connected to the secondary coil has a counter disorder

Measure the current of the line under test. The clamp meter can be changed to different ranges through the dial of the transfer switch, but the operation is not allowed to be live when dialing, in order to facilitate the use, there are also transfer switches of different ranges in the meter for measuring different levels of current and measuring the voltage of the power shield gear energy.

Clamp meter is an instrument that integrates current transformer and ammeter, and is an important branch of digital multimeter, which works on the same principle as current transformer current measurement. A clamp meter is a combination of a current transformer and an ammeter. The core of the current transformer can be opened when the wrench is pinched; The wire through which the measured current passes can pass through the gap where the core is open without being cut, and the core closes when the wrench is released.

The conductor of the circuit under test passing through the core becomes the primary coil of the residual current transformer, in which the passing current induces the current in the secondary coil. Thus, the ammeter connected to the secondary coil has an indication --- measures the current of the line under test.

The clamp meter can be switched by a switch. Dial the base macro file to change to a different range. However, live operation is not allowed when dialing.

Clamp tables are generally not very accurate and are usually graded. For ease of use, there are also transfer switches of different ranges for measuring different levels of current and voltage.

Clamp meters were originally used to measure AC current, but now multimeters have the function to measure AC and DC voltage, current, capacitance capacity, diode, transistor, resistance, temperature, frequency, etc.

The clamp ammeter can measure the photovoltaic DC current and the output AC current of the inverter, it should be noted that some clamp ammeters do not have DC function, and the jaws should be closed tightly and cannot be charged to change the range.

The function and function of the clamp ammeter

1. First of all, correctly select the voltage level of the clamp ammeter, check whether its appearance insulation is good, whether there is damage, whether the pointer swings flexibly, and whether the jaws are corroded. The rated current is estimated based on the power of the motor to select the range of the meter.

2. Before using the clamp ammeter, you should read the manual carefully to find out whether it is an AC or AC or DC clamp meter.

3. Due to the low accuracy of the clamp ammeter itself, the following methods can be used when measuring small currents: first wrap the wire of the tested circuit around a few times, and then put it into the jaws of the clamp meter for measurement. In this case, the current value indicated by the clamp meter is not the actual value being measured, and the actual current should be the reading of the clamp meter divided by the number of turns of the wire winding.

4. The jaws of the clamp meter should be closed tightly during measurement, if there is noise after closing, the jaws can be opened and re-completed once, if the noise can not be eliminated, the joint surface on the magnetic circuit should be checked whether it is smooth and clean, and it should be wiped clean when there is dust.

5. The clamp meter can only measure the current of one phase wire at a time, and the measured wire should be placed in the clamp window**, and the multi-phase wire cannot be clamped into the window for measurement.

6. The voltage of the tested circuit should not exceed the value indicated on the clamp meter, otherwise it is easy to cause grounding accidents or cause electric shock hazards.

7. Measure the working current of the cage asynchronous motor in operation. According to the size of the current, you can check and judge whether the motor is working normally, so as to ensure the safe operation of the motor and prolong the service life.

8. When measuring, you can measure once per phase, or once in three phases, the number on the table should be zero, (because the three-phase current phasor sum is zero), when there are two phase wires in the jaw, the value displayed on the table is the current value of the third phase, by measuring the current of each phase, you can judge whether the motor has an overload phenomenon (the measured current exceeds the rated current value), whether there is a problem with the power supply voltage inside the motor or (the device that can convert other forms of energy into electrical energy is called the power supply), That is, whether the three-phase current unbalance exceeds the limit of 10 parts of the package.

9. Before measuring the clamp meter, the size of the measured current should be estimated first, and then decide which range to use. If it is not possible to estimate, you can use the maximum range first and then change it to a smaller one to get an accurate reading. It is not possible to use a small current to measure a large current. In case of damage to the meter.

<>2.Open the jaws of the clamp meter and connect the clamp meter to the circuit under test.

The access method shown in the figure below is wrong, so that the current consumption of the circuit cannot be measured, but the leakage current of the circuit, which is normally zero.

3.Open the jaws of the clamp meter and correctly connect the clamp meter to the circuit under test, and then the actual current of household appliances can be measured.

The access method shown in the figure below is correct, only a single power cord of the circuit under test can pass through the jaws, and two wires can be tested separately in two times, and the measured values of the two times should be equal in theory, no 4The line is abnormal, and the leakage current is large. The measured current value of the test circuit shown in the figure is.

<>6.After starting the household appliance, the measured starting current is shown in the figure below.

1.Before measuring, check whether the rubber insulation of the clamp core is intact. The jaws should be clean, rust-free, and closed with no visible gaps.

2.When measuring, the current to be measured should be estimated first, and the appropriate range should be selected. If it is not possible, you can choose a larger range first, and then reduce it step by step to switch to the appropriate gear.

When changing the range gear, it must be done without electricity or with the jaws open to avoid damaging the instrument to the nucleus.

3.When measuring, the measured wire should be placed in the middle of the jaw as far as possible, if there is noise on the joint surface of the jaw, it should be reopened and closed once, and if there is still noise, the joint surface should be treated to make the reading accurate. In addition, it is not possible to clamp two wires at the same time.

4.When measuring the current below 5A, in order to get a more accurate reading, when conditions permit, the wire can be wound several times and put into the jaw for measurement, and the actual current value should be the meter reading divided by the number of wires put into the jaw.

5.Before and after each measurement, put the switch to adjust the current range on the highest gear, so as not to damage the instrument due to the disadvantage of measuring without selecting the range during the next use.