Market Wide Half Hourly Settlement (MHHS)

Securing site access for a TAA Inspection Visit

Can the Appointed MOA work on the metering system before the Inspection Visit takes Place?

Information required from audit participants before a TAA Inspection Visit

MOA, LDSO or NETSO attendance at a TAA Inspection Visit

TAA Working Instructions

Information required from the DC or CDCA following a TAA Inspection Visit

Reference 001 – CoP Determination

Reference 002 – Approved Protocols

Reference 003 – Current Transformers and Open Bars (Appropriate Seals)

Reference 004 – Metering Dispensations

Reference 005 – Complex and Non-Complex Sites

Reference 006 – Measurement Uncertainty

Reference 007 – Onshore and Offshore CVA Inspections/Audits (including Aggregation Rules)

Reference 008 – No Access, Supplier, MOA and LDSO

Reference 009 – Passwords

Reference 010 – Phase Rotation

Reference 011 – Resolution of Metering

Reference 012 – Sealing

Reference 013 – Prevailing Load Test

0.0.1 In co-operation with the HHMOA the potential of the Meter cabinet is checked with a reference earth ensuring the Metering cabinet is not live. Any voltage detected is reported to the HHMOA. The visit is aborted where the fault cannot be immediately and safely rectified by the HHMOA. The TAAMT will be updated to record and report the condition, including what action the HHMOA has taken to ensure public safety from the equipment.

0.0.2 The Meter test facility is accessed (appropriate seals removed) and inspected for serviceability, (see figure 6). A visual inspection of the test facility and associated conductors is made to ensure measurement current transformers are not open circuited or short circuited. In accordance with TAA Working Instruction 010 – Phase Rotation the Metering System phase rotation is checked.

0.0.3 Using the handheld energy analyser the TAA measures and records the phase/line voltages. The voltage range will vary depending on the system arrangement – typically 110v line voltage for high voltage installations and 240V phase to neutral and 415v phase to phase for low voltage installations. (It should be noted that on the National Grid and some high voltage sites, it is possible that the voltage measurement could be 63.5v phase to neutral with metering arranged 3ph 4w).

0.0.4 In conjunction with step 2 whilst the recording voltage measurements, following a risk assessment and determination of system arrangement, the TAA will apply the handheld energy analyser’s clip-on CT either on the primary or secondary conductor(s). The corresponding measurements are recorded including system power factor (multiple reads maybe necessary because of variations of load / generation in the primary circuit at the time the measurements are being taken.

0.0.5 All measurement parameters are entered into the prevailing load database in the TAAMT.

0.0.6 Over the measurement period a timed interval is monitored and Meter readings taken depending on the Meter display programming. Preferably the Meter will have a demand register displaying either kW and/or kVA. Start and end readings are taken over a time period, typically ten minutes, however this can be adjusted in reflection of site load/generation. The TAA will ensure that the test period does not cross a half hour boundary, as the demand register resets. Alternatively, if no demand registers are available the cumulative reading can be used noting the value of the Meter Register Multiplier.

0.0.7 For those sites where the load is considered too low to obtain a valid test result (typically less than 5% of the circuit capacity) independent values can be referenced ensuring instant values at meter are matched.

0.0.8 To complete end-to-end checks the cumulative kWh Meter register is recorded at the start and end of a half hour demand period. The advance is compared to the results obtained by local interrogation of the Metering System. Local interrogation results utilising propriety software are recorded and are used as evidence not only for checking the Meter advance but also to perform a CDCC check upon receipt of data made available by the HHDC. Performing a local Meter interrogation validates Meter password security arrangements.

0.0.9 Category 1 or 2 non-compliances will be raised where the test results indicate either that Settlement Data Quality is, or there is a potential that Settlement Data Quality is, affected.

0.0.10 A “Note for Elexon” is recorded in TAAMT to confirm if Measurement Transformer Ratio was established

Reference 014 – Commissioning for Metering Equipment installed before 6th November 2018 or where the Metering Equipment is owned by the Customer

Reference 014(A) – Commissioning for Metering Equipment installed on or after 6^th November 2018 where the Metering Equipment is owned by the Licenced Distribution System Operator (LDSO) or Transmission Company

Reference 014(B) – Pre-June 1993 Commissioning

Reference 015 – CoP4 Records

Reference 016 – Measurement Transformer Certificates

Reference 017 – Fusing and Links

Reference 018 – Outstation Time Keeping

Reference 019 – Overall Accuracy

Reference 020 – Meter Compensation

Reference 021 – Duty of Care

Reference 022 – Checking that Main and Check Meters are correctly identified

Reference 023– Defined Metering Point