The Namibian Grid Code The Metering Code 1 of 6 Code Documents Final May 2005 Enquiries: Electricity Control Board, +264-61-374 300, Namibia Table of Contents 1. Introduction... 3
2. Application of the Metering Code... 3 3. Principles of the Metering Code... 3 4. Responsibility for Metering Installations... 4 5. Metering Installation components... 4 6. Data validation and verification... 5 6.1 Data validation... 5 6.2 Meter verification... 6 7. Metering database... 6 8. Testing of Metering Installations... 6 9. Metering data base inconsistencies... 6 10. Access to Metering data... 6 11. Confidentiality... 7 1. The Namibian Grid Code Metering Code (final 100505) Page 2 of 7
Introduction (1) This code ensures a Metering standard for all current and future Participants. It specifies Metering requirements to be adhered to, and clarifies levels of responsibility. (2) The NRS 057:2001 Metering specification shall be used as the Metering requirements for the Grid Code. The Electricity Control Board (ECB) however reserves the right to override some sections of the NRS specifications should it find them inadequate or divergent from the principles of the Grid Code. (3) This code covers some aspects not fully or clearly addressed within the NRS 057 specification. All areas written into this code will therefore take precedence over the NRS 057 specification. 2. Application of the Metering Code (1) This code shall apply to all Participants in respect of any Metering point at the boundary of the Transmission System (TS). (2) This code sets out provisions relating to - (a) Main Metering Installations and check Metering Installations used for the measurement of active and reactive energy; (b) The collection of Metering data; (c) The provision, installation and maintenance of equipment; (d) The accuracy of all equipment used in the process of electricity Metering; (e) Testing procedures to be adhered to; (f) Storage requirements for Metering data; (g) Competencies and standards of performance; and (h) The relationship of entities involved in the electricity Metering industry. 3. Principles of the Metering Code (1) The following points shall have a Metering Installation: (a) Each Point of Supply connecting a distributor or end-use customer to the TS. (b) Each Point of Connection between a unit and a distributor or the TS. (c) Each point connecting Namibia s networks to a neighbouring country. (2) The type of Metering Installation at each Metering point shall comply with NRS 057 Metering specifications. (3) Each Metering point shall be installed with main and check Metering where practical and economical. Customers with a maximum demand of at least 5 MVA shall have main and check Metering. There shall be separate main and check CT cores but one dedicated VT shall be allowed. (4) A Metering point may be located at a point other than the Point of Connection or the Point of Supply by mutual agreement between the Participants. The Namibian Grid Code Metering Code (final 100505) Page 3 of 7
(5) Customers may request the installation of their own separate check meters. Any extra costs shall be borne by the requesting Party. The Transmission Metering Administrator (TMA) shall install and control such meters. 4. Responsibility for Metering Installations (1) For the purposes of this code, the Transco shall fulfil the role of the Transmission Metering Administrator (TMA) and is the owner of the meter. (2) The Transmission Supply Business (TSB) shall be responsible for ensuring that all points identified as Metering points in accordance with the principles of the previous section s have Metering Installations. (3) The TMA shall be responsible for managing and collecting Metering information. (4) Participants connected to or wanting to connect to the TS shall provide the TMA with all information deemed necessary to enable performance of its Metering duties. (5) In the event of a Metering Installation being positioned between two distributors, the following shall apply: (a) Both distributors shall be responsible for installing and maintaining the Metering Installation in accordance with the requirements of this section. (b) All costs related to this Metering Installation shall be borne by both distributors. (c) The distributors shall ensure that the TMA is given remote/electronic access to the Metering Installation. Should access to the Metering Installation compromise the Security of the installation, then Metering data shall be supplied to the TMA on a daily basis in an appropriate format. 5. Metering Installation components (1) The following principles shall apply to all Metering Installations: (a) The meter(s) or recorder(s) shall be able to store data in memory for 35 days or more. (b) Data stored in either a meter or a recorder shall be remotely (where possible) and locally retrievable. (c) A meter shall be remotely interrogated on a daily basis where possible or as mutually agreed by the affected Participants. (d) A meter shall be visible and accessible, but such access shall be restricted to authorised access only. Data for customers shall be historical data situated on a secure server. As and when required, Metering impulses shall be provided. (e) A telecommunications medium shall be connected to the meter/recorder where possible. (f) The meter data retrieval process shall be a secure process whereby meters or recorders are directly interrogated to retrieve billing information from their memories. (g) The accuracy of meters and recorders shall be in accordance with the minimum requirements of NRS 057-2. (h) Commissioning of the Metering Installation and Metering data supporting systems shall take place in accordance with the requirements of NRS 057. The Namibian Grid Code Metering Code (final 100505) Page 4 of 7
(i) Both active and reactive energy shall be measurable without compromising any requirements of this code. (j) The meters shall measure both active and reactive energy flow in both directions. (k) The meters shall be configured to store/record Metering data in half-hourly integration periods. (2) In the event of a Metering Installation being used for purposes other than Metering data (a) Such use shall not in any way obstruct Metering data collection and accuracy requirements; (b) The secondary use shall be communicated to all Participants who may be affected by the secondary use of the installation; (c) No secondary user shall interfere with VT/CT circuitry. (3) Metering Installations shall be audited in accordance with NRS 057 or equivalent. 6. Data validation and verification 6.1 Data validation (1) Data validation shall be carried out in accordance with NRS 057. (2) In the event of (a) Electronic access to the meters not being possible; (b) An emergency bypass or other scheme having no Metering system; or (c) Metering data not being available (3) Any of the following may be resorted to by the TMA: (a) Manual meter data downloading (b) Estimation or substitution subject to mutual agreement between the affected parties (c) Profiling (d) Reading of the meter at scheduled intervals (4) In the event of an estimation having to be made, the following shall apply: (a) A monthly report shall be produced for all estimations made. (b) No estimation shall be made on three or more consecutive time slots, and if such estimation had to be made, the TMA shall ensure that the meters are downloaded for the billing cycle. (5) Not more than ten (10) slots may be estimated per meter point per Month. If such estimation had to be made, the TMA shall ensure that the meters are downloaded for the billing cycle. The Namibian Grid Code Metering Code (final 100505) Page 5 of 7
6.2 Meter verification (1) In addition to the NRS057 verification requirements, meter readings shall be compared with the Metering data base at least once a year. 7. Metering database (1) The TMA shall create, maintain and administer a Metering database containing the following information: (a) Name and unique identifier of the Metering Installation (b) The date on which the Metering Installation was commissioned (c) The connecting parties at the Metering Installation (d) Maintenance history schedules for each Metering Installation (e) Telephone numbers used to retrieve information from the Metering Installation (f) Type and form of the meter at the Metering Installation (g) Fault history of a Metering Installation (h) Commissioning documents for all Metering Installations (2) Information relating to raw and official values as indicated in NRS 057-4 section 4.2 shall form part of the Metering database and shall be retained for at least five years for audit trail purposes. 8. Testing of Metering Installations (1) Commissioning, auditing and testing of Metering Installations shall be done in accordance with the NRS 057-4 specification. (2) Any Participant may request the ECB or an agency acting on its behalf that testing of a Metering Installation be performed. Such a request shall not be unreasonably refused. The costs of such test shall be for the account of the requesting Participant if the meter is found to be accurate and to the account of the TMA if the meter is found to be inaccurate. 9. Metering data base inconsistencies (1) In the event of testing revealing that data in the Metering database is inconsistent with the data in the meter, the TMA shall inform all affected Participants and corrections shall be made to the official Metering data. 10. Access to Metering data (1) Metering data shall be accessed through a central database that shall store all customer information. (2) The TMA shall control access to all Metering Installations. (3) No electronic access to the meters shall be granted to the customer or any other Party unless special permission has been granted by the ECB. The Namibian Grid Code Metering Code (final 100505) Page 6 of 7
(4) Schedules for accessing Metering data from the central database shall be administered by the TMA in line with NRS 057-4 section 4.2.3. (5) All Security requirements for Metering data shall be as specified in NRS 057. 11. Confidentiality (1) Metering data and passwords are confidential information and shall be treated as such at all times. The Namibian Grid Code Metering Code (final 100505) Page 7 of 7