The power parameter is very important in the electrician, since the rated value of the circuit breakers and the cross-section of the conductors are determined based on it. But this value is not always indicated on the packages or technical documentation of consumers, therefore, the power has to be determined in slightly different ways.
Power, voltage, current
To determine the power, an old formula is used:
P = U * I
From which it can be seen that power is represented as the product of voltage and current. Based on these indicators, you can determine any component of the formula if 2 other values are known. For example, to find out the rated current of an electrical appliance, it is enough to divide the power by the voltage. The voltage in the network is most often 220 or 380 V. And almost every manufacturer of electrical appliances indicates the power on its packaging.
How to Determine Power Using Meters
In order to determine the power of the consumer (electrical appliance), you must have:
- Multimeter.
- Clamp meter. If the consumer current exceeds 10 A.
It is best to have a universal current clamp on hand, among the functionality of which there is also a voltage measurement. But such a device is preferred to buy for themselves by people who are closely related to electricians, and not ordinary average users.
How to determine power using measuring instruments:
1. Measure the current with a clamp or multimeter.
Important! The multimeter is not designed to measure too high current readings. The rated value of these devices usually does not exceed 10 A. At higher values, in the best case, the fuse in the device will blow, in the worst case, the device itself will burn out.
2. Measure the voltage in the network. 380 V is measured between "phases", 220 V - between phase and neutral conductors.
3. Substitute the values into the formula: multiply voltage by current.
The main disadvantage of this method is the availability of the necessary measuring instruments, which not every owner has.
Why do you need to know the power of the consumer?
- Firstly, only knowing the approximate power consumption of electrical appliances can you correctly calculate the cross-section of the conductors to be laid. This has already been mentioned earlier. The rating of the circuit breakers is also selected based on the parameter of the total power of the consumers on the line.
- Secondly, the power of each electrical appliance is a certain electricity consumption over a period of time. Accordingly, planning the funds required to pay for it, which is practically the main factor in such an important area as energy.
I took a closer look at this topic in my new video: