What are the standards for voltage and frequency for electricity use in Vietnam?

What are the standards for voltage and frequency for electricity use in Vietnam? (Internet image) 

According to Article 15 of Decree 137/2013/ND-CP, the Ministry of Industry and Trade of Vietnam is responsible for promulgating regulations on voltage and frequency for electricity use as follows:

• About voltage: In normal conditions, the permitted difference of voltage is about ± 5% in comparison with nominal voltage of power grid and defined at position where equipment for electricity meter is laid or other positions as agreed by two parties. For power grid which has not yet been stable after incidents, the permitted difference of voltage is from +5% to -10%;

• About frequency: In normal conditions, the permitted frequency difference of electrical system is about ± 0,2Hz in comparison with nominal frequency of 50Hz. For power grid which has not yet been stable after incidents, the permitted frequency difference is ± 0,5Hz.

Note: The electricity purchaser for production, business, service with separate substation or without separate substation, provided that the maximum use capacity is 40 kW or more shall:

• Register chart of sub loading and technical and technology characteristics of electric equipment with the electricity seller;

• Ensure coefficient cos φ ≥ 0.9 at points laying equipment of electricity measure in condition of electrical system ensuring quality of electric energy as prescribed at Clause 1 of this Article;

• Install equipment for reactive power compensation in case of coefficient cos φ < 0.9 to increase coefficient cos φ ≥ 0.9 or buy additionally reactive power on electrical system of the electricity seller.

• Within 01 year, after this Decree takes effect, the electricity purchaser must not buy reactive power upon implementing coefficient power cos φ at 0.85 or more;

• Ensure technical standards about harmonics, voltage oscillator, and voltage flicker in accordance with regulations.

If the electricity purchaser is able to generate the reactive power on electrical system and the electricity seller has demand to buy the reactive power, two parties may agree on purchase and sale of the reactive power via contract.

Note: In special case, parties may agree on electric energy quality other than standards

More details can be found in Decree 137/2013/ND-CP, which comes into force from December 10, 2013.

Ty Na

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