Every month, people pay for electricity, the consumption of which is taken into account by an electric meter. However, often the amount of electricity consumed is significantly higher than the actual energy consumption. This casts doubt on the quality of the meter. Let's look at how to check an electric meter at home.
Why do electric meters lie?
During periods of changing seasons, electricity meters often overestimate their readings. These appliances are lying. In various forums you can find many discussions of such cases.
Some people claim that over one night of the refrigerator’s operation, the energy meter calculated as much as 4 kW - that's a lot. At an enterprise that supplies electricity to apartments, residents are told that the meter is working accurately. But engineers from the same enterprises openly declare that they are lying counters, and even how they are lying. This is especially true for budget systems, such as the Mercury counter. He is often complained about.
The real picture is that the metering device can produce inflated indicators even with quite correct operation. The first reason is a decrease in voltage in the network due to the mass use of air conditioners or heating equipment. Household appliances change the efficiency downward if the voltage is below 220 V.
So, to achieve an objective, an electric appliance needs, for example, not 0.19 kV / h in the passport, but from 0.25 and higher. This picture can be observed with all household appliances. It turns out that the same consumer of electricity at a different time on the meter will spend different amounts of energy, although it seems that everything is fine.
In this case, it is necessary to test metering devices in order not to pay energy companies what they themselves have to pay for. The fact is that the electricity supplier is required to maintain the required parameters in the network. If the parameters are violated, then in Europe the supply company pays for it.
When should I check my electricity meter ?
The meter should be checked in cases where there are irregularities in its operation, namely, a strong increase in consumption or, on the contrary, a sharp decline. With an emergency check, do not delay, a quick reaction in this case will avoid serious fines and problems. Also, the check should be carried out when connecting any new equipment, if the energy consumption at the same time remained the same as it was. And another situation is a decrease in real consumption, if the meter has not changed its indicators in any way.
Also, the electric meter is checked once every year. Such timely checks can also help to avoid serious problems.
Are you familiar with the described situations? Then it’s worth using simple tips on how to check the meter yourself. During testing, the device will be checked for self-propelled and error. You will need a stopwatch, a multimeter, a 100 W bulb and a calculator.
Checking the connection
This is a very important point. It is important that the metering device is correctly connected to the mains. It can be a 220 V network or an industrial standard of 380 V.
Single phase meter
In apartments, single-phase meters are used, the network for such apartments is also single-phase. In this case, four terminals are used for connection. The correct circuit is where the phase wire goes from the electrical line to the first terminal of the meter. Through the second terminal, the line usually goes to the apartment. It is also considered correct when the neutral wire goes to terminal 3 and goes through terminal 4. How to check the electricity meter at home for a correct connection? Just count the terminals and see where and what goes.
Three phase meter
For residents of private houses, a slightly different connection scheme is used, since in this case, most likely, a three-phase electric energy metering device is installed there.
Only the number of cables and terminals changes in the circuit. In general, the connection principle is the same - the phase from the electric line is connected to terminal 1, and exits terminal 2. The second phase enters terminal 3 and exits terminal 4. The third phase approaches terminal 5, and exits the sixth. Zero is connected to terminal 7 and goes to the 8th.
That's all you need to know before checking the operation of the meter.
Testing the meter for self-propelled
What is a self-propelled gun? Everything is very simple - it is energy accounting, if at the current moment any consumption is absent. That is, the meter can read the readings on its own, without the use of electrical appliances.
To check that the device’s disk does not rotate on its own, you must completely turn off all the machines that are located in the electrical panel at the bottom of the device and serve sockets, switches. It is also necessary to turn off all electrical appliances.
How to check a home electric meter for self-propelled devices, if there are no automatic machines in the electric network? It also happens - this test is even easier. All electrical appliances, as well as switches are disconnected from the network. In this case, there should be no electricity consumption.
After disconnecting, it is recommended to wait about 10-15 minutes. Then a visual test is performed: if the LED on the front panel blinks or the disk turns, then this device did not pass the test. The owner has no choice but to check the correctness of the electricity meter in the management or service company.
If the device is working, then nothing will either flash or rotate. The LED may flash once in 10 minutes, the disk should make one revolution within the same 10 minutes.
We consider the measurement error
So, during this test, it is necessary to calculate the error of the accounting system. For this, an incandescent lamp, a multimeter, a stopwatch, and also a calculator are useful. An electronic device is best used as a multimeter.
As a load, the most ordinary incandescent lamp is recommended - the whole problem is that modern household appliances can adjust their power depending on the situation. As a result, the nameplate capacity will not correspond to the actual values. If there is an error already at this stage, then the result of the check will not be accurate.
How to check the accuracy of the meter
First of all, you need to measure the mains voltage, here you will need a multimeter. How to use this device, you must know in advance. The number on the display of this measuring device is best written on a piece of paper.
Then measure the current strength of the bulb. The tester is put into current measurement mode and connected to the lamp. Together with the current strength, the power of the bulb is also needed for calculations. This can be found using a simple formula from the school physics course - voltage is multiplied by power. In addition, the bulb resistance should also be calculated - the voltage is divided by the power.
Now it's time to move on to verification. Let's see how to check the electric meter at home for accuracy. To do this, when a light bulb is on, they measure how long it will take for the accounting device 10 blinks with an LED or 10 revolutions of the disk. At the same time, it is necessary to control the voltage in the network. For example, a device can make 10 revolutions in 2 minutes, and the voltage can be 223 V.
Further, on the counter case, it is required to find the value of its constant - it is indicated in pulses per kW / h. Also, the value may be different. For example, an electronic Mercury counter has this data on the front panel.
We use the formulas
Using the formula P = U * U / R, the actual electricity consumption is calculated. This is done in order to find out how much the lamp is actually consuming at the moment.
For verification, it is still necessary to find out how much power was consumed during the verification period, for example, let it be 2 minutes. To find out, the real consumption must be divided by the time of the test, in this case 120 s.
You can check the error by the following formula: 1000 is multiplied by the number of revolutions divided by a constant from the front panel of the device. For example: 1000 * 10/3200. The error is determined by subtracting the figures from the last step from real consumption. Further, all this must be multiplied by 100. If it turned out about 5%, then this is a slight error.
E = (P * T * A / constant number of pulses - 1) * 100%,
where E is the percentage error, P is the lamp power, T is the time it takes for the meter to make one full revolution, and A is the gear ratio of the meter.
Often on the Web they ask questions regarding the counters of the brand "Mercury", as well as "Neva" on the level of magnetization. The thing is that these devices are equipped with a special anti-magnetic seal. If you tried to stop this device using a powerful magnet, then this very seal will change its color. As a result, when checking equipment from service and management companies, serious problems can be obtained.
If the device is not new and its model is simple, then the magnetization is checked with a needle. If it is attracted to the instrument panel, then it is magnetized. The level of magnetization decreases if you remove the magnet from the panel in two to three days. If the device doesn’t even want to demagnetize like that, then special demagnetizers are sold for this.
That's all you need to know about how to check an electric meter at home. This information will help to avoid unnecessary bills and serious problems.