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Regulation regarding requirements for electricity energy meters
Established by the Norwegian Metrology Service dd.dd.yyyy in accordance with the Units of
measurement, Measurement and Standard time Act of 26 January 2007 no 431 §§ 7, 8, 10, 19, 30
and 35 and the Units of measurement and Measurement regulation of dd.dd.yyyy § 5-1(3). In
accordance with EEA-agreement annex II chapter IX no 27b (directive 2004/22/EC).
Chapter 1 – Introduction
§ 1 Scope
(1) This regulation determines which requirements that shall apply for electricity
energy meters that measures active or a combination of active and reactive energy when
a) sold or offered for sale, and when
b) used in low voltage electricity distribution systems as foundation for calculations of
financial settlement.
(2) The regulation applicable for all sale end offer of electricity energy meters is
regulated in chapter 2.
(3) This regulation determines the method of control during use of electricity energy
meters.
(4) This regulation is not applicable for electromagnetic radiation. Regulation on
electromagnetic radiation is to be found in Electrical Equipment regulation of 10 August 1995
no 713.
§ 2 Definitions
a) Electricity energy meter: A device which measures the active electricity energy
consumed in a circuit, including meters that measures reactive energy in
addition to active energy.
b) Low voltage electricity distribution net: Installation with maximum reference
voltage up to 1000 V AC or 1500 V DC.
c) Static meter: An electronic meter.
d) Measurand: The particular quantity subject to measurement.
e) Influence quantity: A quantity that is not measurand but that affects the result of
measurement.
f) Rated Operating Conditions: The rated operating conditions are the values for
the measurand and influence quantities making up the normal working
conditions of an instrument
………….
Chapter 2 - Requirements for electricity energy meters that are sold or offered for sale
Section I – general requirements
……………
Section II – Specific requirements
§ 24 Definitions
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I
In
=
=
Ist
=
Imin
=
Itr
=
Imax
U
Un
f
fn
PF
=
=
=
=
=
=
the electrical current flowing through the meter,
the specified reference current for which the transformer operated meter has been
designed
the lowest declared value of I at which the meter registers active electrical energy
at unity power factor (polyphase meters with balanced load),
the value of I above which the error lies within maximum permissible errors
(MPEs) (polyphase meters with balanced load),
the value of I above which the error lies within the smallest MPE corresponding to
the class index of the meter
the maximum value of I for which the error lies within the MPEs,
the voltage of the electricity supplied to the meter,
the specified reference voltage,
the frequency of the voltage supplied to the meter,
the specified reference frequency,
power factor = cos = the cosine of the phase difference between I and U.
§ 25 Accuracy
The manufacturer shall specify the class index of the meter. The class indices are
defined as: class A, B and C.
§ 26 Areas of use for electricity energy meters
Instrument class A in temperature interval + 5 To be used for residential meters for indoor
o
C … + 30 oC
installation, including rental purposes,
private bed-sits, blocks of bed-sits.
Instrument class B in temperature interval 25 oC … + 55 oC
To be used for residential meters for outdoor
installation, including cabins / holiday
homes.
Instrument class B in temperature interval + 5 To be used for commercial activity / light
o
C … + 30 oC
industry, including common meters in
shopping centres, indoor not transformer
connected.
Also to be used for lighting / heating of
public road with direct-connected meter.
Instrument class C in free temperature
interval
For transformer connected
meters in commercial activity / light industry,
including common meters in shopping
centres.
For housing cooperatives – common meters
with subsequent meters in series.
For lighting /heating of public road which has
transformer connected meters.
Table 3
.……….
§ 28 Maximum permissible errors (MPE)
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(1) The effects of the various measurands and influence quantities (a, b, c,...) are
evaluated separately, all other measurands and influence quantities being kept relatively
constant at their reference values. The error of measurement, that shall not exceed the MPE
stated in Table 5, is calculated as: Error of measurement = √ (a2 + b2 + c2 ...)
(2) When the meter is operating under varying-load current, the percentage errors
shall not exceed the limits given in table 5.
Maximum permissible errors in percent at rated operating conditions and defined load current
level and operating temperature
Operating
Operating
Operating
Operating
temperatures
temperatures
temperatures
temperatures
+ 5 °C ... + 30 °C - 10 °C ... + 5 °C - 25 °C ... - 10 °C - 40 °C ... - 25 °C
or
or
or
+ 30 °C ...+ 40 °C + 40 °C ... + 55 °C + 55 °C ... + 70 °C
A
B
C
A
B
C
A
B
C
A
B
C
Singel phase meter; polyphase meter if operating with balanced loads
Imin ≤ I < Itr
3,5 2
1
5
2,5 1,3 7
3,5 1,7 9
4
2
Itr ≤ I ≤ Imax
3,5 2
0,7 4,5 2,5 1
7
3,5 1,3 9
4
1,5
Polyphase meter if operating with single phase load
Itr ≤ I ≤ Imax
4
2,5 1
5
3
1,3 7
4
1,7 9
4,5 2
For electromechanical polyphase meters the current range for single-phase load is limited to
5Itr ≤ I ≤ Imax .
Table 5
(3) When a meter operates in different temperature ranges the relevant maximum
permissible errors values shall apply.
…………….
Chapter 3 – Requirements for electricity energy meters during use
§ 36 Responsible
(1) Provisions in chapter 3 and 4 are directed to everyone using electricity energy
meters as foundations for calculations of financial settlement. For the purpose of this
regulation ‘user’ means the one that are responsible for the measurement.
(2) The electricity utility company is considered to be responsible for the
measurement if actual circumstances don’t indicate differently. Actual circumstances can be
the location of the electricity energy meter, if its placed outside the electricity utility
company’s net and also who:
a. owns the meter,
b. executes maintenance of the meter,
c. issues bills based on the measuring,
d. finance the expenses in the case of exchanging the meters.
§ 37 Approval of electricity energy meters
Electricity energy meters being sold or offered for sale after 1/1-2003 shall either:
a) have a type approval issued by Norwegian metrology service (Justervesenet), or
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b) have a declaration of conformity according to Norwegian regulations implementing
directive 2004/22/EC on measuring instrument (MID approval).
§ 38 Accuracy classes
(1) Electricity energy meters that have a Norwegian type approval, referred to in § 37
letter a, shall have an accuracy class consisting with area of use according to previous
regulations which the meter was approved according to, before it was sold.
(2) Electricity energy meters that have a MID approval, referred to in § 37 letter b,
shall have an accuracy class consisting with area of use as laid down in § 26.
(3) Electricity energy meters of a better accuracy class may be used if the owner so
chooses. In these cases maximum permissible errors will be according to the accuracy class.
§ 39 Maximum permissible errors
(1) For electricity energy meters that have a MID approval, referred to in § 37 b,
maximum permissible error laid down in § 28, shall apply.
(2) For electricity energy meters that have a Norwegian type approval, referred to in §
37 a, maximum permissible error is established in table 7 and 8.
Maximum permissible errors for single phase and polyphase meter
operating with balanced loads
Value of
PF
Maximum permissible errors in %
current
cos(φ)
Accuracy level 1
Accuracy level 2
Itr ≤ I ≤ Imaks.
2Itr ≤ I ≤ Imaks.
Imin ≤ I ≤ Itr
2Imin ≤ I ≤ 2Itr
1
≠1
1
≠1
1,5
1,5
2,25
2,25
3
3
3,75
3,75
Table 7
Maximum permissible errors for polyphase meter operating with
single phase load and balanced [voltage]
Value of
PF
Maximum permissible errors in %
current
cos(φ)
Accuracy level 1
Accuracy level 2
Itr ≤ I ≤ Imaks.
2Itr ≤ I ≤ Imaks.
Table 8
1
≠1
3
3
4,5
4,5
(3) For electricity energy meters that have neither Norwegian type approval or MID
approval, maximum permissible error is established in table 9 and 10. If these meters don’t
have an accuracy class, maximum permissible error is 3,5%.
Maximum permissible errors for single phase and polyphase meter operating with
balanced loads
Value of current
PF/
Maximum permissible errors in %
cos(φ)
4
For
directconnected
meters
0,1 Ib ≤ I <
Imax
Ib
For
transformer-operated
meters
0,1 In ≤ I < Imax
In
1
Accuracy
class 0,5
Accuracy
class 1
Accuracy
class 2
1
±1
±2
± 3,5
± 1,6
±2
± 3,5
0,5 inductive
Table 9
Maximum permissible errors for polyphase meters operating with only single
phase loads and balanced voltage
Value of current
PF/
Maximum permissible errors in %
cos(φ)
For
For
directtransformerconnected
operated meters
meters
0,1 Ib ≤ I < Imax 0,1 In ≤ I < Imax
Table 10
1
Accuracy
class 0,5
1
±2,5
Accuracy Accuracy
class 1
class 2
±3
± 4,5
§ 40 Other requirements during use
Supplementary requirements:
a) When the voltage is applied with no current flowing in the current circuit, the test
output of the meter shall not produce more than one pulse at 90% and 110% of
operating voltage.
b) The register (counting mechanism) must function. To control this 1kWh must be
run through the meter.
c) The sealing must be intact and according to type approval.
§ 41 Electricity energy meters that don’t satisfy the requirements
(1) Electricity energy meters that don’t satisfy the requirements in this chapter must
be taken out of use and not put into use again before the requirements are satisfied.
(2) All the meters in a group/lot shall be replaced within 1 year in case of negative
outcome from the statistical control, mentioned in § 48.
Chapter 4 – Method for control of electricity energy meters during use
§ 42 Requirements for control of electricity energy meters
(1) Control of electricity energy meters shall be based on either total control as
described in § 46 or statistical control described in §§ 47 and 48.
(2) The control shall ensure that the requirements laid down in chapter 3, are
satisfied. When controlling accuracy, including no-load, at least on of the test programs
described in §§ 43 and 44 shall be performed.
(3) The control must be performed by a laboratory that satisfies the requirements laid
down in § 51.
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§ 43 Test program in laboratory or in field
(1) This test program can be used when the test is performed in laboratory or in field.
This program can be used for both total control and statistical control. It is not required to
combine test in laboratory and in field.
(2) The test procedure:
a) Warming-up: The meter shall be connected and loaded with power for some time
before the test starts, for the meter to reach normal operating temperature.
b) Test of accuracy:
I.
No-load: I = 0A on 90% of Unom and 110% of Unom . In field the test can
be done with normal operating voltage.
II.
Accuracy: The following tests shall at least be performed:
Meters with MID approval referred to in § 37 letter b
Itr at cos(φ) = 1
10 xItr at cos(φ) = 1
10 xItr at cos(φ) = 0,5 inductive
Imax at cos( φ )= 1
Table 11
All other meters
10 % of Ib of cos(φ) = 1
100 % of Ib at cos(φ) = 1
100 % of Ib at cos(φ) = 0,5 inductive
Imax at cos( φ )= 1
c) Three-phase meters shall be tested with single phase load separately on all three
phases (L1, L2 and L3) with Itr at cos(φ) = 1 in addition to the procedure described above.
§ 44 Combined test program
In this test program the group/lot shall be divided in two. One half shall be controlled
according to the program described in § 43. The other half shall be tested in field with the
installations cos(φ) according to following procedure:
Meters with MID approval referred to in § 37 letter b
round about Itr
round about 10 xItr
60 – 80 % of Imax
All other meters
ca 10 % of Ib
ca Ib
60 – 80 % of Imax
Table 12
§ 45 Control intervals
(1) The first control of mechanical meters shall be carried out within 6 years after
production year. If the meter is approved, next control must be carried out within 8 years, and
then every 10. year.
(2) The first control of static meters shall be carried out within 3 years after production
year. If the meter is approved, next control must be carried out within 8 years, and then every
10. Year.
(3) For all meters or groups/lots of meters produced before 1/1-2005, and where the
control still has not began, the first control shall be carried out as soon as possible and in any
case within 2008. After that the meters shall be controlled according to the intervals laid
down in (1) and (2).
(4) Electricity energy meters that have been repaired, shall always be controlled
before they are put into use. After that the meters shall be controlled according to the
intervals laid down in (1) and (2).
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§ 46 Periodical total control
Periodical total control means that every electricity energy meter must be controlled.
The results only have consequence for the electricity energy meter that has been controlled.
§ 47 Statistical control – composition of groups/lots
(1) Statistical control can be used on groups consisting of homogeneous meters, in a
way that ensures that the result is representative for the group.
(2) The production year for all the meters in a group must be within a period of until 3
years. Starting point for the control intervals, mentioned in § 45, determines to be in the
middle of the time period for the group.
(3) The meters shall not have been exposed to intervention. In that case, the meter or
meters must be regrouped. Starting point for the control intervals, mentioned in § 45, is the
time of intervention instead of production.
(4) A group shall be as homogeneous as possible. A group can consist of meters
from different owners.
(5) A group of homogeneous meters is defined by the same meter type identification
determined by Justervesenet.
(6) If there is a desire to separate the meters for indoors and outdoors, two meter type
identifications can be given.
§ 48 Statistical control - method for sampling
(1) Only groups consisting of 18 meters or more can be controlled statistically. For
smaller groups, every meter shall be controlled (§46).
(2) Selection of meters for statistical control of groups consisting of 64 meters or
more, shall be performed after standard ISO 2859-2 (Sampling plans indexed by limiting
quality (LQ) for isolated lot inspection) as displayed in table 13. Limiting Quality (LQ) is 8 %,
which indicates that it is 90 % probability that 92 % of the items in the lot satisfy the
requirements.
Double sampling inspection for electricity meters
No.
Lot size
Sample
Sample
size
Cumulative
sample
size
Number of non-conforming
meters**)
Criteria for Criteria for
acceptance rejection of
of
lot (d)
lot (c)
Spare
meters
Criteria for
required
2nd
sample*)
4.1
up
to
1200
first
second
32
32
32
64
0
1
2
2
1
3
6
4.2
1201
to
3200
first
second
50
50
50
100
1
4
4
5
2 to 3
5
10
4.3
3201
to
10000
first
second
80
80
80
160
2
6
5
7
3 to 4
8
16
7
4.4
10001
to
35000
first
second
125
125
125
250
5
12
9
13
6 to 8
13
25
Table 13
(3) For groups consisting of between 18 and 64 meters, sampling must be done
according to table 14. For these groups there is no second sample and every meter must
satisfy the requirements in this regulation for the group to be approved.
Lot size
Sample
18 – 25
26 – 50
51 – 64
17
0
22
0
24
0
Table 14
(4) Method of or tool for sampling must secure a random selection. More meters
cannot be added after a group is approved.
(5) The sample size can be 10 % larger than necessary. Need for spare meters
beyond this, must be documented.
§ 49 Criteria for when a meter can be replaced in the statistical sample
(1) The meters in a sample must be in normal operational condition and
representative for the group. A meter can be taken out of the statistical sample if it got one of
the following faults:
a) Water in meter
b) Manipulated meter, including vandalism.
c) Burned meter when it cant be established with certainty that the meter it self
caused the fire, or
d) Incorrect group belonging.
(2) In cases as mentioned above (1) the meter is not to be tested. To maintain the
statistical foundation, a new meter from the existing group shall replace the meter.
§ 50 Broken sealing
(1) A meter where the sealing of the case is broken shall still be tested according to
the requirements laid down in chapter 3. Justervesenet can determine the approval of groups
that fail the statistical control due to failed result from testing a meter with broken sealing.
Aspects in the evaluation are the cause and the frequency of broken sealing.
(2) A meter with a broken sealing shall be taken out of use, if it’s not possible to
reseal the meter without risking the quality of the meter.
§ 51 Requirements for laboratories
(2) Laboratories performing control according to this regulation shall:
a) be accredited to perform the tests described in §§ 43 and 44 and be registered at
Justervesenet or
b) be approved for the assignment by Justervesenet and have a quality system that
at least ensures:
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I.
II.
III.
IV.
V.
VI.
that traceability is documented
that the measurement uncertainty is documented and is smaller than
the maximum permissible error required in this regulation,
procedures for all tests described in §§ 43 and 44,
documentation on competence/ qualifications,
requirements for test conditions are described and
procedures for handling of deviations.
(2) The laboratories shall be independent from the ones responsible for establishing
the control system and from the ones responsible for making decisions based on the results
of the test.
§ 52 Requirements for ‘users’ internal system of control
(1) ’User’ of electricity energy meters shall have an internal system of control, which
provides summery of all electricity energy meters that are used as foundation for calculating
of financial settlements.
(2) ‘Users’ internal system of control shall be completely documented in a control- or
quality manual.
§ 53 Reporting to Justervesenet
(1) All users shall report about the control that is being done, the results of the control
and the decisions made based on the control.
(2) Type of error, including possible breach of sealing, shall be registered and
reported according to a precise code determined by Justervesenet. This is also applicable for
errors mentioned in § 49 (1). In addition it can be certain errors on the installation site, and in
the cases where such information are available, the following shall be registered and
reported:
a) error in meter auxiliary devices
b) error in meter constant
c) error in connection
d) transformer not centred
Chapter 5 – Finishing provisions
………….
§ 55 Entry into force
This regulation will enter into force from 1 January 2008.
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