Power Quality

Supply of Electricity under the stipulated standards is a responsibility of the relevant licensees and it has been defined as a Right of an Electricity Consumer.


Public Utilities Commission of Sri Lanka (PUCSL) has issued a regulation (Electricity (Distribution) Performance Standard (Regulation) ) to maintain the quality of electricity supply in Sri Lanka
the license holders should provide the electricity supply services and report the data to the PUCSL as per this regulation
Access reliable and safe electric power to commensurate with the quality standards licensee has agreed to provide is a right of an electricity consumer – ( Consumer Rights and Obligations code)

Reliability of Electrical Supply

1. System Average interruption frequency index – Number of Breakdowns of electricity to one consumer per year
2. System Average interruption duration index – Cumulative duration of Electricity loss (minutes) to one consumer due to breakdown of electricity per year
3. Unserved estimated energy – Unserved estimated energy per year due to the breakdown of electricity
4. An instant normal breakdown indicator
These values are being processed by the Commission. A penalty system will be introduced for the licensees who do not comply with these values. The Commission encourages licensees to provide a continuous qualitative supply of electricity complying to the indexes.

Quality of Electricity

The quality of Electricity involves voltage, frequency, and waveform. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady a.c. frequency close to the rated value, and smooth voltage curve waveform (resembles a sine wave). The lifetime of electrical appliances directly affects from the quality of electricity it gets also the quality of electricity is a very important factor for various industries, self-employed, and public.
As per the regulation, licensees should provide electricity as follows;

Rated (nominal) voltage


    Voltage Variation ( variation during the stability mode)
400V/ 230V + /- 6


11,000 V and above +/ – 6



The licensees report to the Commission on the voltage variation throughout the country as per the regulation. The Commission also monitors and verify the data presents by the licensees.
The electricity consumers will also be compensated for the damages of equipment due to abnormal voltages and phase reversals in the distribution systems from 13th of January 2017.