Can the meter underload be solved with a transformer? 50

The maximum load current of a 10(40A) 220V single-phase watt-hour meter is 40A, while the total load of the meter is.

Original load (new load (7kw) =

The load current has exceeded 70A, so the meter refuses to work.

If you don't want to replace a meter with a larger current, the solution is to add a current transformer.

Connect the secondary line of the transformer to the input of the original meter. The choice of transformer ratio depends on your expansion needs, and its ratio is a multiple of increasing capacity.

In principle, if the current capacity of the watt-hour meter is insufficient, it can be expanded by adding a transformer. In practical applications, the transformer and the watt-hour meter should be used together, and the current transformer used in the watt-hour meter is 5 amperes or 1 amperere for the second time, so it must be replaced in sets. The prepaid meter you use can't directly add a transformer, because you can't control the power with the transformer.

In addition, changing the meter is also the business of the power supply department, and it is not allowed to change it yourself.

The transformer can not be used, the transformer is generally used for the measurement of three-phase four-wire high current generally more than 100A circuit, according to the number of turns through the center, the ratio of the primary current to the secondary electricity is multiplied by the reading of the meter, that is, the degree kWh. The transformer is only used for metering, and it has no effect on insufficient load, either to replace the meter and wire with large current, or to turn on the three-phase four-wire electricity.

It is normal for the meter to be overloaded, the wiring is firm, and the wire diameter is enough. If you want to change the transformer, then the original line is not a bottleneck, and there is still room to open. Electric vehicle charging at home is slow charging, if charging, the line to avoid using other high-power equipment, should be fine.

If it is equipped with a current transformer, then the current of your meter 10 (40) is too large and inappropriate. Because current transformers are generally 5**. The measurement is not very accurate.

Another thing to note is, is it appropriate to lay out the wires before? Can you afford it?

You are not very good in Fenghai, because the load of the meter is caused by the pressure that is expanding, such as feelings only play the role of Danzao, Liang Zhao called for not being able to solve the problem in this intertextual way, and the safety of electricity brings hidden dangers.

Consider replacing it with a 10*40A three-phase prepaid meter.

The size of the transformation ratio of the current transformer selected from the meter is selected according to the load capacity of the line or user.

For example, if the line current is 150A, a current transformer of 200 5A should be selected, which will affect the metering if it is too large or too small. The meter used to measure and charge is generally calibrated by the power supply service company and configured with a suitable transformer, which is practical and does not concern the user.

Precautions for using current transformers:

Precautions for the use of current transformerWhen the current transformer is running, the secondary side is not allowed to open the circuit. Because once the circuit is opened, the primary current becomes the excitation current, so that the magnetic flux and secondary side voltage greatly exceed the normal value and endanger the safety of personnel and equipment. The fuse is not allowed to be connected to the secondary side circuit of the current transformer, and it is not allowed to remove the ammeter, relay and other equipment without bypassing during operation.

The accuracy of the current transformer is determined, and the uncertainty of the transformer is within the range of the national standard. (Accuracy of current transformer 1000 5A uncertainty 2A, accuracy of current transformer 100 5A uncertain.) It is better to choose a current transformer with a rated load current that is close to it.

Answer: The selection of transformer and energy meter should be comprehensively considered according to the accuracy requirements of the measurement, the size to be measured, and the use environment. Workshop load, calculated by 2 amperes per kilowatt current, optional transformer and energy meter are as follows:

1. 60kw:

1. Transformer : low-voltage cast current transformer with a variable ratio of 150 5, an accuracy not lower than the grade, and a capacity of not less than 20VA should be selected;

2. Electric energy meter: it is advisable to choose 3 220 380V3, and the accuracy is not lower than that of the electronic three-phase four-wire electric energy meter; It can also be replaced by a single-phase table of three;

2. 120kw:

1. Transformer : A low-voltage castable current transformer with a variable ratio of 250 5, an accuracy of not less than the next grade, and a capacity of not less than 20VA should be selected;

2. Electric energy meter: the same as the requirements of 60kw.

Because the general accuracy of single-phase meters is, and the three single-phase meters need to be used together according to the error characteristic curve, and their synthesis error is higher than that of three-phase electric energy meters, three-phase four-wire electric energy should be selected for measurement. The accuracy of the current transformer and the electronic energy meter can meet the requirements whether it is used to calculate the unit consumption of the product or the electricity fee.

Above, I hope it will be helpful to you.

The current transformer is too large, and whether the meter is too large, whether it will affect the following two situations: 1. When the conversion ratio of the current transformer is too large, that is, when the excitation current is more than 120% of the rated current, due to the saturation of the internal core, the excitation current is large, which will produce serious negative errors, so as to reduce the electric energy. If it is operated under overload for a long time, it will burn out the windings or shorten the service life of the current transformer, and in severe cases, it may burn the current transformer.

2. The conversion ratio of the current transformer is too small, that is, when the excitation current works below 5% of the rated current, its accuracy will be reduced, and a large negative error will also be generated. The Technical Management Regulations for Electric Energy Metering Devices (DL T448-2000) stipulates: "The determination of the rated primary current of the current transformer shall ensure that the actual load current in normal operation reaches about 60% of the rated value, and shall not be less than 30%.

In actual use, the current change range should be guaranteed to be between 5% and 120%, because the excitation current of the current transformer accounts for a small proportion and the measurement is more accurate. When the rated current is less than 5%, the accuracy level of the current transformer is not ***, and when it is greater than 120% of the rated current, the current transformer may be burned. Hope it helps.

Hello, dear <>

1. The meter wiring of the transformer is correct, and if it does not go, it may be that the mechanical energy meter turntable is rotating, the pulse light of the electronic meter is flashing, the reading does not go out, the integrator is faulty, and the integrator needs to be replaced. 2. The turntable of the loaded mechanical electric energy meter does not rotate, and the pulse light of the electronic meter does not flash, which may lose voltage or the voltage coil burns out the open circuit or the voltage sampling board fails, and the voltage coil or voltage sampling board needs to be replaced. Notes:

When the current transformer is connected to the circuit, it is necessary to pay attention to the terminal symbol and its polarity of the current transformer. The letters L1 and L2 are usually used to indicate the terminals of the primary winding, and the terminals of the secondary winding are represented by K1 and K2. Generally, when the primary current flows in from L1 and L2 out, the secondary current flows out from K1 to K2 through the measuring instrument (at this time, it is positive), that is, L1 and K1, L2 and K2 are of the same polarity.

The secondary side of the current transformer must have one end grounded in order to prevent it.

When the insulation of the primary and secondary windings breaks down, the high-voltage electricity on the primary side is connected to the secondary side, endangering the safety of personnel and equipment. I hope my answer is helpful to you, and finally I wish you good health and a happy mood again! <>

Hello dear! Glad for your question! Is it okay to install a transformer without a load in a three-phase meter? No, the purpose of the current transformer is to convert the large current on the line into hundreds or thousands, convert it into a current of 1A or 5A, and use it for measurement and use in the power supply meter.

There is a range of requirements for the current of the three-phase meter, not that the three-phase meter must be connected to the current transformer, and the current transformer that exceeds the current range of the meter must be equipped with a current transformer, and the ratio size and accuracy level of the mutual inductance or respect device, and the rated load are required. There is also a difference between a meter with a current transformer and a meter without a current transformer. If the current of the meter is exceeded and the current transformer is not connected, the measurement accuracy will be inaccurate, the meter will burn out, and even a fire will occur.

It is to ask if the watt-hour meter will go when the load is small. The current is very small, and the watt-hour meter will not go. For example, the energy meter with an accuracy level 1 requires that its starting current is not more than a multiple of the rated current, that is, the energy meter with a rated current of 5A is qualified without the following words.

If the transformer ratio is 200 5, when the load current is below, the electric meter may not go. If the transformer ratio is 50 5, the load current is below when the meter may not go. Therefore, the transformer can not choose too big, and the Huai will greatly reduce the sensitivity of the meter and reduce the number of words when the load is small.

Meters can have built-in transformers. In fact, many modern meters have built-in transformers, which are known as "electronic transformer built-in energy meters" or "transformer energy meters". The transformer of this type of meter is usually installed inside the meter and connected to the circuit board of the meter to measure the current.

This reduces the cost of installation and maintenance of transformers, and improves the accuracy and reliability of the meter. Meter ridges with built-in transformers are commonly used in low-voltage power grids and are suitable for industrial, commercial and domestic electricity metering.