As the power system and people’s relationship is getting closer and closer, more and more people realize that in today’s time to master a certain electrical knowledge has become a life must, from the daily maintenance of small household appliances to the size of the home solar energy system selection, design. In fact, regardless of the size of the power system, its design to the basic knowledge is the same. In order to better understand the workings of an electrical system, we need to learn about various physical quantities and the conversion relationships between them, and today we need to learn about the conversion from watts to amperes.
1. What is a watt (w)?
A watt is a unit of power. It is often used to describe how much energy an appliance requires to do its job. the higher the wattage, the more energy it requires to operate, and conversely, the lower the wattage, the less energy it requires to operate. 1w is defined as 1Wh of energy per hour of operation. e.g., a refrigerator with a wattage of 2,000w requires 2,000Wh of energy per hour of operation.
2. What is an ampere (A)?
An ampere is a unit of current. It is often used to describe how fast a charge moves in a circuit. From a microscopic point of view, it indicates how much charge passes through a section of a circuit in an instant.
3. What is the volt (v)?
The volt is a unit of voltage, which is often used to describe the amount of charge carried by a current through a section of a circuit, i.e., the magnitude of the current force. The greater the value of the volt in a circuit, the greater the force of the current in that circuit, and conversely, the smaller the value of the volt, the less the force of the current in that circuit.
From a microscopic point of view, it is a unit used to measure a unit of electrons in the electric field due to different TV produced by the energy difference between the number of units, the size of its value is equal to a unit of positive charge due to the action of the electric field force from one end of the circuit to the other end of the amount of work to be done, and therefore can be said that the volt is the potential energy potential.
4. How is the conversion of watts to amperes achieved?
Although the watt and the ampere are both units used to measure forms of electrical power, there are significant differences: the watt is a unit of electrical power, while the ampere is a unit of current within a circuit. Therefore, watts cannot be directly converted to amperes, and in order to do so, we must introduce an intermediate physical quantity, namely: the volt. The volt is the unit of voltage and according to Watt’s law has:
P (w) = V (v) x I (A)
The formula for converting watts to amperes can be obtained by morphing the above equation:
I (A) = P (w) ÷ V (v)
In order to help you better understand and grasp the formula, we will illustrate the specific use of the formula with an example below. When you buy a household refrigerator with a power of 3300w, and the voltage of the household power supply is known to be 110v, then the operating current of the refrigerator is 3300w ÷ 110v = 30A.
5. Is there a difference in the conversion of watts to amperes between DC and AC? Where is the difference in the way they are calculated?
First of all, we need to know that there are two different types of current in a circuit, alternating current (AC) and direct current (DC). In the case of DC, the current flows in one direction only, while the current in AC changes its direction according to a certain time frequency. Generally, all currents in homes are AC.
The formula we have studied above are only for DC current, but for AC current, which is more widely used, the operation of the circuit is more complex, and therefore the formula for calculating it are also more complicated.
First of all, alternating current is mainly divided into single-phase alternating current and three-phase alternating current.
Single-phase alternating current
Single-phase alternating current is alternating current that has only one AC voltage in the circuit.
The formula for converting single-phase AC watts to amps is:
I(A) = P(w) ÷ {PF x V(v)}
Where PF is the power factor, a value used to measure the phase difference between voltage and current in a circuit. The greater the phase difference between voltage and current in a circuit, the lower the power factor, the lower the efficiency of the circuit, and the less stable the entire system. It is worth noting that the formula V refers to the RMS voltage, that is, the circuit and can produce the same heating effect of the DC voltage value, the main reason for its existence is because the voltage in the AC circuit will change with time, the calculation of the RMS value to facilitate the calculation.
Three-phase alternating current
Three-phase alternating current (AC) is a power system consisting of three alternating current potentials with the same frequency, the same potential amplitude, and a phase difference of 120° from each other, and is the most commonly used type of alternating current.
There are two formulas for calculating the conversion of watts to amperes for three-phase alternating current, which are:
Calculate the RMS voltage by changing it to the line-to-line voltage (V L-L)
I(A) = P(w) ÷ {√ 3 × PF × v L-L (v)}
and, changing the RMS voltage to line-to-neutral voltage (V L-N) calculates
I(A) = P(w) ÷ {3 × PF × v L-N (v)}
6. Calculations about your solar system
When you know the rated generating power of your solar system, you can derive the total current of operation by using the above formula. Since household appliances are now connected in parallel to ensure that they operate independently of each other, the total current that your solar system is able to supply can help you determine how much it can supply to the appliances that are running. In turn, if you know the total current of the appliances in your home, the above formula can also help you choose the size of your solar system. The data required for this calculation can be obtained by looking at the outer packaging of the solar panels.
