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What are rated voltage, rated power and rated current?

Many people have heard of rated voltage, rated power, and rated current.What do those three words mean? From the word “rating”, we can learn this is a standard.

Rated voltage:

The rated voltage of the product will be marked on the nameplate on all electrical equipment or materials.

In China, the rated voltage of electrical appliances is usually 220V, and the rated voltage of industrial equipment is 380V. This is because the grid here only supports these two voltages.Therefore, the electric rice cooker and toilet lid bought in Japan cannot be directly connected to the socket, which requires to use a special equipment to reduce the pressure.

Rated voltage, is the ideal working voltage of the equipment. But the fact that the voltage in our lives is just stable at 220V is very rare. It depends on the size of the local transformer and the amount of electricity used at the same time. If the voltage is too low, so low as to be less than 200V, it may cause the appliance to be out of use.Such as incandescent lamp brightness reduction, engine speed reduction and so on. But if the voltage is too high, it will have more serious consequences.

Careful users may find 250V ~ on the nameplate, which means the highest voltage.If the voltage is higher than 250V, it will affect the safety of products, including fire, leakage of electricity and other accidents, which are very easy to happen. Generally, new residential areas, because the voltage device did not debug normal, prone to the situation of high voltage, need to be particularly careful. The size of voltage, directly affect the power of electrical appliances.

Rated power

What is the power?  It is the amount of work done by an electrical appliance.

Here, the rated power, refers to work efficienty under the rated voltage of electrical appliances. The rated power of electrical appliances is also in the factory design, but in actual use, there are two factors can make it change –

  • Voltage. Voltage level, can directly change the actual power.Power is proportional to voltage.
  • The environment.The external environment such as temperature and humidity can change the resistance value of the conductor inside the electrical appliance and indirectly change the actual power of the electrical appliance.The power is inversely proportional to the resistance value.
  • Rated power, is the design power of the product, such as a fan, its design speed is 2000 RPM.When the voltage or external environment changes, the actual speed of the fan may be faster or slower.

Rated current

A fire or an electrical appliance, it’s all about the current.When an electric current passes through, it heats up, and heat accumulates, causing a fire or burning down an electrical appliance.

Rated current = rated power/rated voltage (I=P/U).

In addition to the rated current, the nameplate is usually marked with the maximum current. The maximum current here refers to the maximum instantaneous current that the appliance can withstand. Always exceed rated current to run for a long time, it is harmful to electrical appliances. When the maximum current is exceeded, the appliance will burn down instantly.


Post time: May-31-2019
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