THE ENERGY Regulatory Commission (ERC) detailed on Wednesday the inspection process for meters and instrument transformers to be used in the power system in a package of rules on device certification issued last week.
In a resolution, the ERC said the standards will cover distribution utilities (DUs), customers connected to the distribution system, redistributors, generators and the transmission network provider (TNP). The resolution, posted on its website, is known as the Rules Governing Accuracy Limits, Accuracy Testing and Standards, and Other Requirements for the Certification and Testing of Meters and Instrument Transformers.
In its resolution, the ERC said that all watt-hour meters or devices that measure electricity must first be tested, certified and sealed by the commission before they are used commercially.
Under the new rules, watt-hour meters with a minimum of 600 volts, below 69,000 volts and 69,000 volts and above are now assigned accuracy limits. The voltage levels of instrument transformers will be used in determining their accuracy limits.
Similar to watt-hour meters, all instrument transformers in DUs must be tested and certified by the ERC prior to installation in the customers’ premises. An instrument transformer reproduces the current of its primary circuit.
“ERC stickers shall be attached to the instrument transformers by the ERC as a warranty that they are compliant with the standards and requirements under existing rules and regulations, and may, therefore be used,” the commission said.
Instrument transformers of the generators and the TNP will be tested in accordance with the Philippine Grid Code.
The ERC added that instrument transformers have varying accuracy classes depending on whether they conform to IEC (International Electrotechnical Commission) and ANSI (American National Standards Institute) requirements.
The rules state that generators, TNPs and DUs must ensure the proper installation of instrument transformers. “All instrument transformers shall remain accurate at all times, while in service,” the ERC said.
Transformers that are believed to be defective will undergo accuracy testing by the ERC.
Based on the fees and charges for instrument transformer testing, laboratory testing of instrument transformers costs P290 per tap and on-site spot testing P1,160 per tap.
The resolution was signed by ERC Chairperson Agnes VST Devanadera and three commissioners on Feb. 18, and was posted on the ERC’s website on March 31. — Angelica Y. Yang