Figure 159 The outlet layout example of hospital grade (Connected to isolating TR) and normal grade

Chapter 2-6 Measure the electrical energy (Metering)

Chapter 2-6-1 Metering System

Article 160. General Requirements

(1)The requirement of power metering system

1.Measurement system for power grid voltage of 110kV or more:

-Position the main meter is defined identical or adjacent to the connection point.

-In case of failure to qualify for the main meter layout prescribed or position does not ensure accurate measurement of power delivery, power distribution units and customers to agree the location and installation of replacement meter, and define the power conversion method from the measured position instead of the connection points.

2.Installation of meters for power grid voltage 1000V to 35kV

3.Installation of meters for low voltage grid

4. When the power purchase boundary is not determined, there shall be agreement between electricity buyer and seller and approved by authorized agency.

5.When electricity can be exchanged two directions at the boundary, the two directive meters or one multi directive meter must be installed.

6.Selection of mechanical meters or electronic meters and requirement to transmit data from meters must be performed in compliance with existing regulation of the power sector.

Counting active electricity must ensure determination of active electricity amount:

1.Generated by each electrical generator.

2.Own used in the power plant, substations including compensating station and diesel power generation station.

3.Supplied to or received from other power system.

4.Provided by power plant to transmission and distribution network.

5.Supplied to electricity consumers.

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Apart from ensuring counting electricity for billing, counting electricity must also ensures inspecting electricity used by consumers, checking electricity exchanged at boundary, electricity balancing, development of technical-economic indicators and electricity load forecast.

Counting reactive electricity must ensure determination of reactive electricity amount:

1.Generated by each electrical generator.

2.Provided by power plants to transmission and distribution power networks.

3.Generated by rotary compensators or static compensating stations.

4.Supplied to or received from other power systems.

5.Of electricity consumers, production-business, services facilities which have transformers with capacity of 100kVA and above or used capacity of 80kW and above.

Apart from counting reactive electricity for billing, counting also plays function of checking,

monitoring, used by consumers, checking electricity exchanged at boundary, electricity balancing, development of technical-economic indicators and electricity load forecast.

(2) Location for electricity meter installation

Purchase electricity meter installed identical or adjacent to the connection point or at a convenient location agreed upon by the buyer and the seller.

Metering System should be carried as follows:

- In power plants and power systems, active electricity meters must be installed at:

1.Each electricity generator.

2.Each step up transformer, at econdarys side high and medium voltage sides, except balancing

winding.

Side of transformer, at which electricity is exchanged in two directions, twodirectiveoneelectricity meters or one two-directive meter must be installed. When low voltage of step up transformer doesn’t have own current transformer for meter, the meter must be installed at voltage of generator.

3.Each out going line feeder from substation, except low voltage feeder to public consumers or exclusive low voltage out going feeders which have meters at terminals of power lines. The power lines on which electricity is exchanged in two directions, two -dironective electricity meters must be installed.

4.Two directive meters must be installed at both ends of power line which is connectingwerpo systems.

If power line has branch connected to the other electricity network, two directive meters must be installed at the end of branch.

5.Auxiliary transformer:

The meters are installed at high voltage side of the auxiliary transformer. If installation at high voltage side is difficult, installation at low voltage side is also allowed.

6. Each auxiliary generator: If auxiliary generator has it own power supply, at this part meter must be installed.

- In substation, active electricity meters must be installed at:

1.Both inlet of power line, two director meters or one two director meter must be installed.

2.Low voltage side of two-winding transformer.

3.Low and medium voltage sides of three winding transformer, except balancing winding

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4.Each outgoing line feeder, except low voltage feeder to public consumers or exclusive low voltage out going feeders which have meters at terminals of power lines.

5.Each auxiliary transformer.

- Active electricity billing meters for consumers must be installed at:

1.Each outgoing line feeder, except low voltage feeder to public consumers or exclusive low voltage out going feeders which have meters at terminals of power lines.

2.At inlet of consumer’s substation if it doesn’t connect with other substations or otherconsumers

at its supply voltage.

3.At inlet of consumer’s substation if it supplies electricity to or connecting to substations of other consumers at supply voltage. When having not current transformer with accuracy class required by measuring circuit at35kV and above, meter is allowed to be installed at low voltage side of

the transformer.

4. Low voltage side of transformer if at high voltage side there is load switch, automatic disconnector or fuse bridge switch.

5. Out going line feeder to many consumers. Even each consumer has its separate meter, it needs a general meter for monitoring and checking.

- Reactive electricity meters must be installed at:

1.Electricity generator with capacity of 1,000kVA or more.

2.Medium voltage and low voltage windingsof transformers and important places where active electricity meters are installed. If there is no current transformer with accuracy class as required, reactive electricity meter is allowed to be not installed at low voltage side of the transformer.

3.On 35kV power line, if billing electricity to consumers is based on active meters of that power line.

4.At outlet of compensating machine or at main line of capacitor with capacity of 100kVA or more.

5.Near to active electricity billing meters of motive electricity consumers.

6.At elements of electricity system, boundary requiring billing or monitoring reactive electricity.

7.At consumers with generated reactive electricity, two directive reactive electricity meters must be installed.

8.At boundary with power exchange, two directive reactive electricity meters must be installed.

-Meters must be installed on rigid board, cubicles or boxes. Meters are allowed to be installed on metal, stone or plastic boards but not on wooden boards.

-In places where are easy to be hit, dusty and many people passing or external interference, meters must be placed in cubicles or boxes with lock, sealing and hole for peering through.

Many meters can be placed in one box or cubicle or in the same place with low voltage current transformers.

-Connecting wires to meters must be copper conductors used for connection with crossectionals

area not less than 1.5mm2 in compliance with requirements.

-Wire connecting with the meter circuit must not be connected and not welded.

-Wiring section close to meter must have 120mm surplus at least. Cover of “zero” wire before meter must have easy recognized color at least 100mm of terminal.

-Distance between electricity conducting parts on electric board with meter and current transformer must comply requirements specified in Article 413.

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- In low voltage electricity network, when being installed in dangerous and very dangerous halls,

the covers of meters and current transformers must be grounded through separated copper conductors (“zero” wire).

-When two or more meters are installed close to each other, there must be name plates for each meter

In power plants or substations with two or more meters installed, there must be name plats for each meter.

(3)Backup Metering

A Metering System shall be considered faulty and not in compliance with this Distribution Code if it is determined that any part of that Metering System does not comply with this Distribution Code.

If a Metering System fault occurs, the Distributor shall provide Urgent Metering Services to repair or replace the Metering System as soon as is reasonably practicable and in any event within two working days of the Distributor discovering that the fault exists.

The User shall use Metering Equipment in a safe and prudent manner andshall take due care to avoid damage. The User shall notify the Distributor of any damage to the Metering Equipment, however caused.

The Distributor shall ensure that suitable data is obtained or estimated for the period of time commencing when a Meter or Metering Equipment becomes faulty until the completion of the repair

or replacement.

The Distributor shall record all relevant Meter parameters for a replacement Meter in that Metering System.

(4) Payment meters

As specified in the Technical Regulation.

Article 161. Power metering system configuration

1.Fully configurable for power metering system include:

a)current transformer;

b)voltage transformers;

c)the power meter;

d)the secondary circuit and cable

e)equipment for metering data collection and transmission of data;

f)equipment safety, position for sealed, pair of lead;

g)equipment for auxiliary equipment, to transfer connection, equipment to isolate the measurement circuit, when need to test

And logic devices for transfer connection voltage circuit to anotherVT, equipment to check the voltage and current

2.Specific configuration of a metering system is determined by the voltage level and the characteristics of the location of measurement..

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Article 162. Requirements for equipment of power system measurements

(1). Electric power metering system 110kV and above

1.Requirements for the power meter:

a)Type 3-phase 4-wire;

b)Type of integrated electronic and programmable function;

c)There are many tariffs;

d)Measurement of active and reactive power in two separate receiver and transmitter by 4- quadrant

e)The maximum power measurement function, recorded total load chart;

f)The appropriate protocol to collect, read the data in local and remote;

g)Supplied from the secondary voltage measurement system and to maintain the operation to in the event of loss of any one or two phase voltage;

h)There are multiple levels of password;

i)The sealing position, leaded ensure inaccessible to the wiring terminals and change the settings in the meter if not sealed lead break;

j)Information storage function measurement, load charts least 60 days with cycle recording measured values do not exceed 30 minutes;

k)For metering system to at the main meter placement, the measured active power meter must have accuracy class 0.2 according to IEC 62053-22 and accuracy class 2.0 according to IEC 62053-23 if reactive power measurement or other equivalent standards;

l)For backup metering systems, meters measure the active power to achieve the accuracy class of 0.5 according to IEC 62053-22 and accuracy class 2.0 according to IEC 62053-23, if measured reactive power or other equivalent standards.

2.Requirements for measuring current transformer for measure of power:

a)With separate secondary windings used to measure the electrical energy

b)The nominal value of the secondary current is 1A or 5A;

c)The location for the lead seal in the lid of the box to the joints of the secondary coil wiring to measure the for power meter to ensure that no impacts on circuit connection without breaking the seal;

d)Current transformer for main meter must achieve accuracy class of 0.2 according to IEC 60044- 1 or equivalent standards

e)Current transformer for backup meter must achieve accuracy class of 0.5 according to IEC 60044-1 or equivalent standards

3.Requirements for voltage transformers used to measure the electrical energy:

a)With separate secondary windings used to measure the electrical energy;

b)The nominal value of the secondary voltage is 100V or 110V;

c)The location for the lead seal in the lid of the box to the joints of the secondary coil wiring to measure the power meter to ensure that no impacts on circuit connection without breaking the seal;

d)Voltage transformers for main meter must achieve accuracy class of 0.2 according to IEC 60044-2 for type electromagnetic-induction-transformer and standard IEC 60044-5 for type capacitor-transformer or the other equivalent standard;

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e)Voltage transformer for backup meter must achieve the accuracy class of 0.5 according to IEC 60044-2 for type electromagnetic-induction-transformer and, standard IEC 60044-5 for type

capacitor-transformer or other equivalent standards.

(2). Power measuring system from 1000V to 35kV

1.Requirements for the power meter:

a)To meet the requirements specified in points a, b, c, d, e, f, g, h, i, j, of this article;

b)For the main metering system, power meter measured the active power to achieve the accuracy class of 0.5 according to standard IEC 62053-22 and accuracy class 2.0 according to IEC 62053-23 if measured reactive power or other equivalent standards;

c)Accuracy class of backup measurement system (if any) shall be determined by agreement between unit sales and customers using electricity.

2.Requirements for current transformer for metering power:

a)With the secondary coil of separate measurement used for measuring equipment and power meter;

b)The nominal value of the secondary current is 1A or 5A;

c)lead-sealed position in the wiring box cover secondary measurement coil for measuring equipment and power meter ensure no impact on circuit connection without breaking the seal;

d)Current transformer for main measurement to achieve the accuracy class 0.5 according to IEC 60044-1 or equivalent standards

e)Accuracy of current transformer metering service backup (if any) shall be determined by agreement between the Power Distribution Unit and Client using the distribution grid.

3.Requirements for voltage transformers used for electricity metering

a)With the secondary coil separate of measurement used for measuring equipment and power meter;

b)The nominal value of the secondary system voltage is 100V or 110V;

c)sealing position in the wiring box cover secondary measurement coil for measuring equipment

and power meter ensure no impact on the circuit connection;

d)Voltage transformers for metering must achieve accuracy class 0.5 according to standard IEC 60044-2 for type electromagnetic-induction-transformer and standard IEC 60044-5 for type capacitor-transformer or the target other equivalent standard;

e)Accuracy of metering voltage transformers in service backup (if any) shall be determined by agreement between the Power Distribution Unit and Client using the distribution grid.

(3). Low-voltage measurement system

1.Requirements for the power meter:

a)A type 3-phase 4-wire or 3-phase 3-wire measurement using 3-phase-meter, and 1-phase 2-wire type using one-phase-meter;

b)The position sealing, leaded ensure no access to the wiring terminals and change the settings in the meter without breaking the seal;

c)For 3-phase meter, active power meter measurement, must achieve the accuracy class 1.0 according to IEC 62053-21 standard for electronic type meter, standard IEC 62053-11 for induction type meter or other equivalent standards. For 1-phase meter, active power meter measurement, must achieve accuracy class 2.0, according to IEC 62053-21 for electronic meter type, IEC 62053-11 standard for induction type meter or other equivalent standards.

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2.Requirements for current transformer when using for low voltage power measurement

a)The secondary coils are separated for the measurement equipment and power meter;

b)The nominal value of the secondary current is 1A or 5A;

c)Lead-sealed position in the wiring box cover secondary measurement coil for measuring equipment and power meter ensure no impact on circuit connection without breaking the seal;

d)To achieve the accuracy class 0.5 according to IEC 60044-1 or other equivalent standards.

Article 163. Requirements for the connection of energy measuring system

1.Cable of secondary measuring circuit must be accompanied by the shortest route, the number of connections over the clamp is at least qualified and have implemented measures seal lead the circuit to be measured at the connector.

2.For metering system 110kV and above, the secondary coil of CT, VT and secondary cable connected to the power meter of the main metering system is not used for any other purpose and must be completed independent measuring system backup. The second main metering system to separate and directly from the wiring box of CT, VT meter cabinets without intermediate in the cabinet clamps.

3.Where is a voltage meter from one of busbarsVT through the switching voltage device, the connected terminals of voltage circuit switches to ensure lead-sealed conditions and power meter must be programmed to record the time and duration of the switching voltage.

4.Secondary circuit load CT, VT, including power meter load should not exceed the normal capacity of CT, VT.

5.In the Case circuit current of the backup measurement system used in conjunction with other measurement devices, must not affect the accuracy of the measurement system and eligible to perform lead-sealed for all of current circuit, measuring devices and power meter.

6.The test boxes must be installed to test for the verification of measuring equipment eligible to seal lead.

7.The technical requirements and the accuracy of the meter:

Distributors must ensure that the accuracy of each meter in each measurement system certified by laboratory testing meter was officially recognized and approved by the Ministry of Science and Technology and that the meter meets the provisions current limit accuracy.

In the case of not meet required standards, the distributor must restore the accuracy of the meter in the measurement system to achieve standards of accuracy in the shortest time reasonably practical. Distributors shall maintain Profile certification qualified related to the specific type and model of the meter in the metering system.

The distributor shall maintain records of the information refer to in this section for each measurement system for at least six years and will provide the data upon request of the competent authorities, inspection and testing of installation .

8.Periodical inspection

The Distributor shall be based on the minimum requirement from the Directorate for Standards and Quality (STAMEQ), ensure that each Metering System is inspected according to these minimum frequencies:

a)1-phase meter: 5 years

b)3-phase meter: 2 years

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