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Guidance Notes

CONTENTS

Technical Assurance of Half Hourly Metering: Categories of common non-compliance for Inspection Visits

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Technical Assurance of Half Hourly Metering: Categories of common non-compliance for Inspection Visits

Guidance Note

Summary

Technical Assurance of Half Hourly Metering Systems (TAM) is a Perfomance Assurance Technique (PAT) described in Section L of the Balancing and Settlement Code (BSC) and in BSC Procedure 27 (BSCP27)1 . The PAT involves inspecting a sample of Half Hourly Metering Systems by the Technical Assurance Agent (TAA) through Inspection Visits and Desktop Audits.

The TAA audits Metering Systems against a set of checks prescribed in BSCP27 Appendix 4. Checks may differ according to Metering Equipment and version of the applicable Code of Practice (CoP). Where the Metering Equipment or the related documentation does not comply at the time of the inspection, the TAA will raise a non-compliance.

This guidance note covers examples of common types2 of Inspection Visit non-compliances that the TAA may identify. For information on Desktop Audit non-compliances please refer to the Technical Assurance of Metering – Desktop Audit guidance, or the Technical Assurance Agent Local Working Instruction –Desktop Audits.

Inspection Visit non-compliances fall under one of these categories:

Consumption Data Comparison Check (CDCC) Failure

    • NC: Consumption Data Comparison Check identified inconsistent data and is deemed to affect the quality of data for Settlement Purposes;

    • NP: Consumption Data Comparison Check not performed. It is deemed to have the potential to affect the quality of data for Settlement purposes

Category 1: A non-compliance has been identified which is deemed to be currently affecting the quality of data for Settlement purposes;

Category 2: A non-compliance has been identified which is deemed to potentially affect the quality of data for Settlement purposes; and

Observation: A non-compliance has been identified which is deemed neither to affect nor to have the potential to affect the quality of data for Settlement purposes.

Details of the planned Inspection Visits, information relating to the Metering Systems inspected and non-compliances raised by the TAA are all available on the Technical Assurance Agents Management Tool (TAAMT) – the TAA’s online system3.

The appropriate party (e.g. the Registrant, the Meter Operator Agent (MOA) or the Data Collector) is expected to provide information on the rectification/rectification plan to the TAA. Once provided by the party, rectification details are also available on the TAAMT.

Non-compliance categories previously removed from the non-compliance list are marked as such. Existing non-compliances relating to removed categories remain open and rectification is still required.

Non-compliances and Observations

Consumption Data Comparison Check

The TAA carries out a Consumption Data Comparison Check (CDCC), which compares the energy recorded by the Metering System during the inspection visit with the consumption data held at the Half-Hourly Data Collector (HHDC) or Central Data Collection Agent (CDCA) for the same Half-Hour. This provides greater assurance of the quality of data entering Settlement by ensuring that it is consistent with the energy recorded by the Metering System. If the values differ by more than the agreed tolerance, currently ±5%, the TAA raises a non-compliance; as an ‘NC’. If the TAA cannot carry out the check for any reason, it records this as an ‘NP’ (‘not performed’) as shown in the table below.

Consumption Data Comparison Check (CDCC)

NC

Comparison identified inconsistent data

Consumption data held by Data Collector outside tolerance when compared with metered energy data

NP

Comparison not performed

Check not performed

The following tables contain the common non-compliances, listed by non-compliance reference number

Table 1

Category 1 Non-Compliances

1.01

Inaccuracy of Standing Data (Key MTD fields) held by Data Collector4

Outstation serial number

Meter ID (serial number)

Outstation number of channels

Measurement Quantity ID

Pulse multiplier

Channel configuration

Outstation multiplier/Outstation channel multiplier

Complex Site Supplementary Information Form (SVA only)

1.02

Metering Equipment Incorrect or Unsatisfactory

Metering Equipment not functioning correctly

Metering Equipment not programmed correctly

Overall accuracy of Metering System not maintained

Summation CTs used5

Correct Energy Measurement Check (Primary/Secondary conductor prevailing load test) indicates an error in the metered volume Measurement Transformers not located at Defined Metering Point

1.03

Timing Error (Major)

Outstation clock outside agreed tolerance6

1.04

Measurement Transformer Ratios Physically Incorrect

Measurement transformer rations different from those set up in Meter (except for any difference being consistent with a measurement error compensation applied within the Metering Equipment)

1.05

Compensation Calculations Incorrect

Meter compensation for Measurement Transformers Incorrectly applied or not applied

Meter compensation for Power Transformers incorrectly applied or not applied

1.06

Miscellaneous

Other non-compliance not covered elsewhere

Table 2

Category 2 Non-Compliances

2.01

Inaccuracy of Standing Data held by Meter Operator Agent4

Outstation serial number

Meter ID (serial number)

Outstation number of channels

Measurement Quantity ID

Meter Register Multiplier

Pulse multiplier

Channel configuration

Outstation multiplier/Outstation channel multiplier

Measurement Transformer Ratios

Complex Site Supplementary Information Form (SVA only)

2.02

Inaccuracy of Standing Data (non-Key MTD fields) held by Data Collector4

Data Collector’s Meter Technical Details do not match on site equipment due to recent Meter Exchange

Other non-Key fields (e.g. Measurement Transformer Ratios, Meter Register Multiplier)

2.03

Non-provision of Standing Data

Meter Technical Details not provided4 – Meter Operator Agent and Data Collector

Complex Site Supplementary Information Form not provided (SVA only)

2.047

Not used

2.058

Not used

2.06

Metering Equipment Incorrect or Unsatisfactory

Incorrect CoP applied

Check Meter missing

Main Meter missing, Check Meter present and accurate

Voltage selection relay not installed/working when Summation CTs used5

Meter Accuracy class incorrect

CT accuracy class incorrect

VT accuracy class incorrect

Unapproved data format and protocol in use

Possibility that overall accuracy of Metering System not maintained

2.079

Measurement Transformer and/or Meter Certificates

Certificates not provided

Certificates do not match on-site equipment

2.08

Unsuitable Environment

Environmental conditions likely to cause Metering Equipment failure

2.09

Inadequate Over-current Protection

Insufficient discrimination between source and local fusing

No local isolation

Main and check Meters not separately fused

Other Metering Equipment not separately fused

Non-settlement Meters not separately fused

2.10

Separate Phase Failure Alarms not Installed or Inadequate/Failed – Local and Remote

Alarm not fitted where required

Alarm not functioning

2.11

Inadequate Metering Equipment Integrity

Settlement Metering Equipment not sealed

Password functionality not included in Outstation10

2.1211

Metering Equipment Test Facilities

Lack of adequate Metering Equipment test facilities

2.13

Miscellaneous

Other non-compliance not covered elsewhere

2.14

Timing Error (Minor)

Outstation clock outside agreed tolerance12

2.15

Commissioning Records

Commissioning records not provided

Commissioning records incorrect

Commissioning records incomplete

2.16

Measurement Transformer Certificates not provided or incorrect

Measurement Transformer Certificates not provided

Measurement Transformer Certificates do not match site equipment

2.17

Meter Certificates not provided or incorrect

Meter Certificates not provided

Meter Certificates do not match site equipment

Table 3

Observations

0.01-0.1413

Not used

0.1514

Suitable Environment (minor)

Environmental conditions not likely to cause immediate Metering Equipment failure

0.16

Labelling Inconsistency

Main/Check/Import/Export

Circuits (feeders)

Measurement Transformer ratio and/or polarity

Test Terminal Block connections

0.17

Standing Data (excluding Key MTD fields) (see ‘Meter Technical Detail non-compliance’)

Inaccuracy in any fields other than those in 1.01 and 2.01 or incorrect site contact name

Miscellaneous

0.18

Other inconsistency not covered elsewhere

0.19

Test Terminal Block

Test Terminal Block not fitted/inappropriate

0.20

Unauthorised Access

Possible unauthorised access to Meter location which could lead to interference with Metering Equipment

Use of ‘Notes’ by the TAA

Occasionally, the TAA Inspector will record additional information about a visit, to provide more information to a party about that inspection or any non-compliance found. The TAA use a ‘Note’ for this function; they are visible in TAAMT with the non-compliances.

More information about non-compliances

This section provides more information on the category of non-compliance considered when a failure is identified for clock timing errors and Meter Technical Details (MTDs).

Outstation clock timing errors (NC 1.03 and 2.14)

The relevant CoP for a Metering System defines the tolerance levels of Outstation clock timing errors. Any error outside these tolerances is a non-compliance. The table below defines when a timing error against Co-ordinated Universal Time (UTC) is categorised as either a Category 1 or Category 2 non-compliance based on the extent of the error:

Code of Practice15

Category 1 Non-Compliance

Category 2 Non-Compliance

CoP 1

>± 30 seconds

± 20 - 30 seconds

CoP 2

>± 30 seconds

± 20 - 30 seconds

CoP 3

>± 1 minute

± 20 seconds to 1 minute

CoP 5

>± 2 minutes

± 20 seconds to 2 minutes

Meter Technical Detail non-compliances (NCs 1.01, 2.01, 2.02 and 2.03)

This section details the process that the TAA follows when reviewing the accuracy of MTDs and determining the category of non-compliances. The workflow diagrams in Appendix 1 outline this process.

Only the MOA and HHDC16 need to provide MTDs to the TAA17. However, the Registrant may want to seek assurance that the MTDs it holds are correct and may want to submit its own data to the TAA for validation. If the HHDC or MOA does not provide MTDs, a Category 2 non-compliance (NC 2.03) is raised against each agent that does not provide these.

If the TAA finds a non-compliance in the MTDs held by the DC, it determines whether the inconsistency is against those items in the Key MTD Fields. If this is the case, the TAA raises a Category 1 non-compliance (NC 1.01). This is because the DC’s MTDs are used in Settlement and affect the quality of Settlement data. If the TAA determines that the inconsistency is not against Key MTD Fields, the TAA raises a Category 2 (NC 2.02). The DC needs the assistance of the MOA to rectify the non-compliance, but it is likely to be the DC who provides rectification details to the TAA.

Any non-compliance found in the MTDs held by the MOA may potentially impact Settlement and therefore a Category 2 non-compliance (NC 2.01) is raised.

If the TAA finds the Registrant’s MTDs to be non-compliant, the TAA only ‘Notes’ that the Registrant’s MTDs are incorrect, as these MTDs are not used directly in Settlement.

Recent Meter Exchanges

Where there is evidence of a recent Metering Equipment exchange, the TAA follows a slightly different process when reviewing the DC’s MTDs.

Where the HHDC has provided incorrect MTDs and there is evidence they are incorrect because of a recent change, the TAA initially raises a Category 2 non-compliance (NC 2.02) and requests that the DC provides a new set of MTDs.

If the new MTDs submitted are correct, the Category 2 non-compliance (NC 2.02) is closed. If the new MTDs are still incorrect, the TAA retains the non-compliance (NC 2.02).

Meter Technical Details – Non-compliances applied by party type:

CDCC - NC

Category 1

Category 2

Registrant

None

None

None

HHDC

If the consumption Data Comparison Check identifies inconsistent data

If Key MTD Fields are incorrect (NC 1.01)

If MTDs are not provided (NC 2.03) or if non-Key MTD Fields are incorrect (2.02)

MOA

None

None

If MTDs not provided (NC 2.03) or if MOA MTDs are incorrect (NC 2.01)

Definition of Key Terms

Term

Definition

Recent Meter Exchange

An exchange of Metering Equipment between notification of inspection visit and date of inspection visit

Key MTD fields

Those data items in the Meter Technical Details (MTDs) used by the MOA to request a proving test

Measurement Transformers

Means Current Transformers (CT) and Voltage Transformers (VT) in the context of this document

Summation CTs

The Metering and Data Collector Sub-Committee ruled on 2 April 1998 (MDC 86/1972) that Summation CTs were no longer acceptable for Settlement use and no retrospective action was required. Metering Systems installed prior to this with Summation CTs shall not have a non-compliance applied for the use of such CTs.

Metering definitions

Metering Equipment is a BSC defined term and refers to all equipment associated with the metering installation. Such as Meters, Outstation. CTs, VTs and any communication equipment. When this Metering Equipment is commissioned by the MOA is comprises the Metering System

Consumption

In the case of the CDCC, the check can be applied to either or both import and export quantities as determined by the TAA

Contact Us

If you have any queries on this document, or if you’d like to know more about the Technical Assurance of Metering process, please contact us at tametering@elexon.co.uk

You can also find out more from the Technical Assurance of Metering Systems pages of our website.

Need more information?

For more information please contact the BSC Service Desk or call 0370 010 6950.

All other terms used and their definitions are in the BSC, BSCP27, the Codes of Practice and the Glossary on the BSC Website:

Intellectual Property Rights, Copyright and Disclaimer

The copyright and other intellectual property rights in this document are vested in Elexon or appear with the consent of the copyright owner. These materials are made available for you for the purposes of your participation in the electricity industry. If you have an interest in the electricity industry, you may view, download, copy, distribute, modify, transmit, publish, sell or create derivative works (in whatever format) from this document or in other cases use for personal academic or other non-commercial purposes. All copyright and other proprietary notices contained in the document must be retained on any copy you make.

All other rights of the copyright owner not expressly dealt with above are reserved.

No representation, warranty or guarantee is made that the information in this document is accurate or complete. While care is taken in the collection and provision of this information, Elexon Limited shall not be liable for any errors, omissions, misstatements or mistakes in any information or damages resulting from the use of this information or action taken in reliance on it.

2 This guidance does not provide an exhaustive list of non-compliances that the TAA identifies.

3 The TAAMT is accessed via www.elexon-assurance.co.uk. If you want to register for access, please contact the TAA at taa_service@candc-uk.com

4 More information about Meter Technical Detail non-compliance is in section 3.2.

5 Metering and Data Collector Sub-Committee ruling 2 April 1998 (MDC 86/1972). See ‘Summation CTs’ in the section 4 glossary.

6 More information about Outstation clock timing errors is in section 3.1.

7 2.04 has never been used

8 2.05 has never been used

9 2.07 was removed in February 2009 (PAB93/08) and replaced with 2.16 and 2.17

10 Password functionality in Outstation is not required in some earlier issues of CoPs

11 12 removed in February 2007

12 More information on Outstation Clock Timing Errors is in section 3.1.

13 0.01 to 0.14 have never been used.

14 0.15 was removed in February 2009 (PAB93/08).

15 All CoPs, including Scottish and historical CoPs (e.g. A to K2) are available on the BSC Website

16 This includes Half Hourly Data Collectors (HHDCs) and the Central Data Collection Agent (CDCA).

17 Responsibilities and timescales for submission of MTDs are detailed in BSCP27