Domestic Smart Meter Installation – ANSI 12.20 Electricity Meters

This article is about Domestic Smart Meter, Smart Meter Connectivity, Smart Meter Installation as per International Standard ANSI 12.20 Electricity Meters.

Domestic Smart Meter, Smart Meter Connectivity

Domestic Smart Meter

1. Basic Technical Specifications of Domestic Smart Meter

1.1 Voltage Level Specification

All Domestic Smart Meters shall be specified for 3-Phase, 4-wire, wye-connected operation under the System Frequency and Voltage Design Basis set out in SAES-P-100, specifically Table 1.

1.2 Labelling

Each Smart Meter shall be furnished with the following labeled information:

● Smart Meter Serial Number
● Manufacturer, Type, Model Number
● Connection Diagram
● Current Rating
● Voltage Rating
● Frequency Rating
● Current Transformer (CT) and Potential Transformer (PT) ratios applied (if applicable).

● Number of phases and connection type
● Year of manufacture
● Accuracy Class
● Protective Class
● Ingress Protection Class
● Protocols supported
● Standards complied with (both International10 and Saudi Aramco)

1.3 Measurement Specifications

A. Measured Quantities

Each Smart Meter shall be capable of measuring the following quantities:

● Voltage
● Current
● Power (Active and Reactive), of which the following parameters are included:

o Instantaneous Import/Export values (W, VArs)
o Maximum Import (W, VArs demanded) over a given period (daily or monthly option)
o Maximum Export (W, VArs demanded) over a given period (daily or monthly option)

● Energy (Active and Reactive) , of which the following parameters are included:

o Current Daily Consumption/Production values (kWh, kVArh)
o Historical Daily Consumption/Production values (kWh, kVArh), for the previous week
o Total Consumption/Production values (kWh, kVArh) for entire operating duration

B. Active and Reactive Power & Energy Quantities

The Smart Meter shall be capable of measuring Active and Reactive Power Quantities with the following stipulations:

● Instantaneous power measurements (active and reactive) shall be Class 1.0 accurate (as per ANSI 12.20).
● Energy measurements shall adhere to the following Accuracy Classes:

o IEC 62053-21 (Class 1 for Active Energy Readings)
o IEC 62053-23 (Class 2 for Reactive Energy Readings)

C. Import and Export Power and Energy Quantities

For the avoidance of doubt, the direction of power and energy flows shall follow IEC conventions (Figure 7, Appendix B). Meters shall retain separate registers on which to measure import and export power and energy:

● Energy and Demand/Micro-Generation Values shall be measured and stored according to their actual values (i.e., based on the primary side value of the CTs and PTs)

● At least 4 registers shall be reserved for the provision of pulsed energy readings for pulse/kWh and pulse/kVArh monitoring, import and export

● Import and export power and energy measurements will be stored in such a way that a customer may be billed/reimbursed separately for their import and export contributions.12

1.4 Time-of-Use (ToU) Pricing Function

● The first three paragraphs of §6.2.1.2 apply here.
● The functionality specified in §6.2.1.2 may be shared across the IHD and MECM, or be present within both devices.
● Smart Meters shall be capable of transmitting price related information across the HAN, e.g., different tariff rates, for use by the IHD (§6.1.1) and Smart Appliances within the End-Customer Devices Application Layer (Figure 5).
● There is a need to align current price/kWh with current tariff rate (e.g., via auto-configuration of data tables).

● Domestic Smart Meter shall facilitate the introduction of a Distributed Generation market through which households can be rewarded for their use of Micro-Generation (if applicable), e.g., apply ToU tariffs to metered exports13.

1.5 CT, PT Specifications

● CT and PT ratios shall be calibrated as part of an on-site survey.
● No auxiliary CT or PT shall separate the main CT/PT from the energy meter.
● Accuracy class of CTs/PTs shall be equal to or exceed that of the energy meter.
● All CTs shall be configured with own dedicated path to ground (as per IEEE STD C57.13.2).

2. Operational Requirements of Domestic Smart Meter

2.1 Grid Connection

The Domestic Smart Meter shall:

● Be capable of sustaining a continuous current of 100 A applied simultaneously to all 3 phases for long periods for Bachelor House Units and 200 A for Family House Units.

● Have an internal main three phase, 3 wire Load Switch, which is:

o Suitable for Pre-payment purposes
o Suitable for Load Limiting purposes
o Rated to make on fault current and break up to 100 A for Bachelor Housing Units and 200 A for Family Housing Units, applied to all three phases simultaneously.

● Have an internal main three phase Load Switch wherein all contacts operate simultaneously on making and breaking operations.

● Have three separate phase indicators which indicate and identify any one or more disconnected supply lines (e.g., service fuse ruptured, etc.).

2.2 Device Reliability

A. Standard Requirements

The Smart Meter shall be:
● Manufacturer guaranteed for a usage period of at least 10 years.
● Able to continuously operate in extremely hot (up to 70°C) and humid (up to 95 % non-condensing humidity) environments.

● Able to operate on a contingent basis in such a way that it temporarily mitigates the adverse effects of one of the following scenarios:
o Loss of NAN communications
o Loss of HAN communications
o Loss of mains power supply
o Assertion of corrupt firmware

B. Diagnostics

The Smart Meter shall:

● Be capable of performing a self-test (initiated either remotely or via secure, direct, physical interaction).

C. Isolated Operation Requirements (Network Connectivity) e.g., As experienced during a loss of NAN communications.

The Domestic Smart Meter shall:

● Have (at minimum) the capacity to store readings locally, in the absence of utility communications, whilst operating with full monitoring capability, on non-volatile memory for a continuous 24 hour period (over which readings are taken at 15 minute intervals).

D. Isolated Operation Requirements (Power Supply)

e.g., Smart Meter is mandated to operate from battery source during a loss of mains power supply.

The Smart Meter shall:

● Have a battery which will keep the internal clock functioning for a minimum of 24 months when the meter is not on supply.
● Send a “last-gasp” message to the Utility in the event that its battery is about to expire.
● Communicate within the NAN via non-default, back-up communications, if required.

E. Firmware Requirements

The Smart Meter shall:
● Be capable of receiving and installing a firmware update (initiated either remotely or via direct local access) without having to power down.
● Retain one previous version of firmware (non-active) as a local back-up.
● Autonomously revert from the default firmware version to the back-up in the event that the default version is corrupted (e.g., just after a new version has been uploaded).

F. Hardware Resets

The Smart Meter shall:
● Feature restoration capability designed to overcome surge induced micro-processor freezing events.
● Retain any static data indefinitely whilst off supply.

2.3 Remote Utility Access

The Domestic Smart Meter will:
● Be responsive to remote Enabling/Disabling (of Load and/or connected Micro-Generation Modules) upon receiving relevant encrypted instruction from Utility.
● Trigger main load switch upon receiving relevant encrypted instruction from Utility.
● Trigger software reset upon receiving relevant encrypted instruction from Utility.

● Upgrade device firmware upon receiving relevant encrypted instruction from Utility.
● Roll-back device firmware (to previous stable version) upon receiving relevant encrypted instruction from Utility.
● Perform self-test upon receiving relevant encrypted instruction from Utility.

2.4 Local Memory

The Smart Meter shall:
● Have data retention capability to store data locally within the AMI.
● Clear the internal memory allocated to a batch of metered data only (at least) 24 hours after a positive acknowledgement has been received from the DCU.
● Have a non-volatile memory resource to render it effective during power outages.

2.5 Time-Synchronization

The Smart Meter shall:
● Possess an internal clock, synchronized with the AMI’s GPS-based, central timestamp.

3. Smart Meter Installation

Wiring Connections

As per §6.5.1.2, the final wiring connection shall be displayed on a diagram on the label.

The Smart Meter shall:
● Be capable of operating accurately when connected to 2 phases of a 3 phase 4 wire supply (i.e., 2 phases, 120° apart).
● Be capable of operating accurately when connected to a single phase of a 4-wire supply (i.e., 2 or 3 live lines derived from the same phase source)15.

4. Robustness and Physical Security

4.1 Incorrect Wiring

The Smart Meter shall:
● Be specified to withstand any inadvertent or ill-advised connection of phase-to-phase voltages between phase and neutral terminals.

4.2 Electromagnetic Interference (EMI) Mitigation

● Meter components shall be mounted on a non-metallic plate to avoid EMI from the backside.
● Meter operation shall be resilient to local magnetic fields and near-field EMI radiation from in-home electronic devices and local environmental sources.
● EMI immunity shall be tested as part of the installation process.

4.3 Tamper Proof Protection

The Smart Meter shall:
● Have seals and a covering shall be applied such that the terminal and front covers cannot be opened, except by authorized maintenance personnel.
● Possess different levels of password access. These should be provided within the AMI for electronic downloads of software/firmware updates, device resets, etc.

4.4 Environmental Exposure

The Smart Meter shall:
● Be guaranteed for continuous operation within air temperatures of up to 70°C.
● Be guaranteed for continuous operation within humidity of up to 95 %.
● Be designed with a minimum IP 54 Rating, as per IEC 60529, to protect against dust and water ingress.

● For implementations that are housed externally to the building, the device shall be furnished with a Weatherproof Metering Box.
● For implementations that leverage GSM/GPRS communications (§6.5.8, §6.5.9) the SIM card holder will be protected with a sealable cover.

5. Customer Interface and Display

It is expected that the Display functionality shall be shared between a technical, operational data view (displayed at the MECM device) and a customer-facing data view (pricing, consumption history, etc.) at a local In-Home Display (IHD) module.

Each feature listed below refers to the MECM only, although some features may also be present through the IHD (see §6.2.2).

5.1 Display Specification

The Smart Meter shall have the following:
● Liquid Crystal Display (LCD)
● Local Push Button Interface
● Convenient User Guide

5.2 User Information

The following data should be apparent to the user:
● Current Price/kWh
● Battery Status
● Local 24-hour time display (consistent with §6.5.2.5)
● Synchronization indication with central AMI control
● Date
● Peak Demand History
● Date/time of last meter reset or power-down
● Instantaneous measurements
● Voltage readings for all 3 phases
● Phase Current
● Power (W, VAr, VA)
● Energy (Wh, VArh)

● Peak Demand (last 24-hours) plus time of occurrence
● Peak Micro-Generation (last 24-hours) plus time of occurrence (if applicable)

6. Interface with Hand-Held Units (HHUs)

Connectivity

● Each Smart Meter shall have at least one Optical Port through which local testing and configuration can be performed via a Hand Held Unit (HHU).
● The Optical Port shall facilitate local reading of all register values.

7. Interface with Home Area Network (HAN)

A lack of clear distinction, from Saudi Aramco’s perspective, between the requirements of a residential HAN and a network deployed within a commercial building, means that this section specifies the MECM-HAN interface within a residential setting. In the event that clear guidelines for Smart Metering in relation to Building Automation Systems are made, this document shall be updated to reflect these changes.
The following requirements shall be provisioned within any “Smart Home” implementation:

7.1 Smart Meter Connectivity

The Smart Meter shall:
● Be equipped with a RS-485 interface and at least 2× RJ45 terminals through which connections to external gateways and sub-meters can be facilitated.
● Be configured to transmit values to the local IHD (§6.2) to facilitate a near real time indication of energy consumption.
● Be capable of transmitting On/Off commands to HAN-enabled switches/contactors.
● Configure a data table that facilitates switching in the HAN and allows for switching commands to be aligned with start and finishing times of selected tariff rates.

7.2 Active Power, Current and Active Energy consumption of “Smart Devices” within the HAN shall be measured through the MECM.

7.3 Master End-Customer Meter (MECM) shall be able to perform Distributed Control for individual loads within the HAN.

Aggregated commands dispatched by the Utility are interpretable within the DCU Application Layer. These are then relayed to Domestic Smart Meters located downstream.

The following control of Smart Appliances shall be possible through the MECM:
● Temperature set-point control (Thermostats Only)
● Scheduling of operating times
● Coarse On/Off capability

This requirement only relates to the MECM and not sub-meters.

Additional requirements for the MECM-HAN interface, such as acceptable communications protocols, are provided in §6.4.

8. Interface with Neighborhood Area Network (NAN)

The DCU Application Layer and therefore the NAN Communications Layer, is optional, according to which architectural Solution (A or B) is specified (see §4 for more details). Thus, this section of the specification only applies for Solution A.

8.1 Connectivity

The Smart Meter shall be equipped with one or all of the following interfaces:
● PLC Transceiver (Interface to NAN; Applicable for Solution A only)
● GSM/GPRS Transceiver
● RS-485 interface and at least 2× RJ45 ports.

The Smart Meter shall:

● Register with the NAN, by handshake with the DCU for that NAN.
The following requirements are made of the communications protocols to be supported within the NAN Layer:

8.2 Interoperability

The AMI solution shall employ open17 standard metering protocols to assure inter-operability with any newly installed energy supplier equipment, as well as consumer equipment during the life-period of the meter.

8.3 Acceptable Protocols (between Domestic End-Customers and DCUs)

The following protocols are acceptable for communications across the NAN layer, between Smart Meters and DCUs:

● DLMS/COSEM (IEC 62056-62, 62056-53)
These protocols have been selected due to their versatility (in terms of Transport Layer) and interoperability with other protocols.

8.4 A single, active interface shall exist between the End-Customer and NAN layers.

A single Smart Meter within the End-Customer premises shall be designated as the Master End-Customer Meter (MECM).

8.5 Data Exchange

● Data shall be formatted into XML (open standard) for the exchange of data between Metering Systems, Local Devices and Authorized Parties.
The Smart Meter shall:
● Send metered data (demand and Micro-Generation), sub-metered data and user-defined schedule information to the DCU upon request.

8.6 Visual Availability Indication

● The availability of communications to/from the meter will be apparent via local indication (e.g., red/green light notification)

8.7 Acknowledgement

The Smart Meter shall:
● Send acknowledgement that Utility initiated overrides have been successful or failed.
● Receive and interpret acknowledgements from its assigned DCU upon reporting metering data or HAN schedules.

8.8 Transport Layer

The following transport layers are deemed acceptable for the provision of communications between Domestic End-Customers and DCUs:
● Fiber-Optic (FO) cable,
● Power Line Carrier (PLC), using OFDM modulation
● GSM/GPRS.

9. Interface with Wide Area Network (WAN)

The DCU Application Layer, and so the NAN Communications Layer, is optional according to which architectural Solution (A or B) is specified (See §4 for more details).
In the event that the DCU and NAN Layers are excluded from the AMI (Solution B) an interface is formed between the MECMs and the WAN Communication layer. Thus, this section of the specification only applies for Solution B. However, many of the requirements specified for the MECM-NAN interface (§6.5.8) will still apply here.

9.1 Connectivity

The Smart Meter shall be equipped with one or all of the following interfaces:
● GSM/GPRS or VSAT Transceiver
● RS-485 interface and at least 2× RJ45 ports.
● Ethernet
The Smart Meter shall:
● Register with the WAN, directly, by handshake with the NOC (Solution B).

9.2 Interoperability

See §6.5.8.2.

9.3 Acceptable Protocols (between Domestic End-Customers and the NOC)

The following protocols are acceptable for communications across the WAN layer, between Smart Meters and the NOC:
● DLMS/COSEM (IEC 62056-62, 62056-53)
● Other, yet to identified open standard protocols.

9.4 Data Exchange

See §6.5.8.5, replacing all instances of “DCU” with “NOC”.

9.5 Visual Availability Indication

See §6.5.8.6.

9.6 Acknowledgement

See §6.5.8.7, replacing all instances of “DCU” with “NOC”.

9.7 Transport Layer

For WAN communications, SAES-P-126 takes precedence over this document, where applicable. The following transport layers are deemed acceptable for the provision of direct communication links between Domestic End-Customers and the NOC:

● Fiber-Optic (FO) cable
● GSM/GPRS
● VSAT

We have discussed Domestic Smart Meter, Smart Meter Connectivity, Smart Meter Installation as per International Standard ANSI 12.20 Electricity Meters.

All article related to Smart Metering Technology are linked below step by step.

Advanced Metering Infrastructure | Smart Metering Technology

Advanced Metering Infrastructure Functionality – AMI Functions

Advanced Metering Infrastructure System Design Architecture

Advanced Metering Infrastructure Components

Advanced Metering Infrastructure Functional Requirements

Domestic Smart Meter Installation – ANSI 12.20 Electricity Meters

Data Concentrator Unit | DCU Principle with Technical Specification

Head End System for Advance Metering Infrastructure

Meter Data Management System – IEC 61968-9

Wireless Communications Principles and Industrial Practice

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