CZECH 
METROLOGY 
INSTITUTE  Okružní 31, 638 00 Brno  
legmet@cmi.cz  
+420 545 555 414 
 
1. ------IND-  2019 0298 CZ-  EN- ------ 20190703 --- --- PROJET 
Executive summary for the EC (not part of this legislation)  
'Current measuring transformers' may be placed on the market and put into use in the Czech Republic 
as specified measuring instruments  in accordance with Act  No 505/1990 on metrology, as amended.  
According to the act, specified measuring instruments are in struments which are included in the list of 
the types of specified measuring instruments (Decree No  345/2002) and, at the same time, intended (by 
the manufacturer/importer) for measurements of relevance for the protection of public interests in 
consumer pr otection, contractual relations, imposition of sanctions, fees, tariffs and taxes, health 
protection, environmental protection, occupational safety, or the protection of other public interests 
protected by separate legislation . This means that their purpose is similar to that used for defining 
specified products –  measuring instruments and non- automatic weighing instruments – under Directives 
2014/31/EU and 2014/32/EU. The requirements of this regulation do not apply to measuring instruments 
placed on the m arket in the Czech Republic for purposes other than the above purposes defined by Act 
No 505/1990 on metrology.  
The subject matter of this notified regulation is to lay down the metrological and technical requirements for specified measuring instruments of  this type. This regulation also lays down the tests for the purposes 
of type approval and verification of specified measuring instruments of this type.  
(End of executive summary)  
 
P U B L I C  N O T I C E 
 
The Czech Metrology Institute (CMI), as the body competent and relevant for the determination of 
metrological and technical requirements for a specified measuring instrument and for the determination 
of type approval tests and verification of a specified measuring instrument pursuant to Section 14(1) of 
Act No. 505/1990 On Metrology, as amended (Metrology Act), and pursuant to the provisions of 
sections 172 et seq. of Act No. 500/2004 Coll., the Administrative Procedure Code, as amended 
(hereinafter the “Procedure Code”), initiated on 21.12.2009 pursuant to Section 46 of the Procedure 
Code, and, based on supporting documents, issues the following:  
 
 
I. 
D R A F T  G E N E R A L  M  E A S U R E 
number:0111- OOP -C088 -18 
laying down metrological and technical requirements for specified measuring instruments, 
including the testing methods for verification of the following specified measuring instruments:  
'current measuring transformers'  
 Measure of a General Nature No  0111- OOP -C088- 18 
 
2 1 Basic definitions  
For the purposes of this General Measure, terms and definitions pursuant to VIM and VIML1 and the 
followi ng must apply:  
1.1 
current transformer  
an instrument transformer whose secondary current is proportional to the primary current, and has a 
phase angle difference of almost zero when properly connected  
1.2 
current instrument transformer (CIT)  
a transformer whose secondary current is for practical purposes proportional to the primary current 
during normal operating conditions; the phase difference between the primary and secondary current 
vectors approaches zero when suitably connected  
1.3 
nominal primary cur rent 
the primary current value specified on the current transformer's nameplate and upon which its operation 
is based  
1.4 
nominal secondary current  
the secondary current value specified on the current transformer's nameplate and upon which its 
operation is  based  
1.5 
current error εI (conversion error)  
the error the transformer introduces into current measurement and that follows from the fact that the 
actual conversion is not equal to the nominal conversion. This current error, expressed in percent, is 
given by the formula:  
()
pp sn
IIIIK 100−=ε (%) (1) 
where  Kn ........ is the nominal conversion,  
Ip ......... is the real primary current,  
Is .......... is the real secondary current corresponding to the primary current I p under measurement 
conditions.  
1.6 
angle error δI 
the phase shift between the primary and secondary current phasor; the primary and secondary current 
phasor orientation are chosen so that an ideal transformer would exhibit zero error. The angle error is 
considered positive if the secondary current phasor Is precedes the primary current phasor Ip. It is usually 
expressed in arcminutes or centiradians.  
NOTE:  This definition is correct only for AC power with a sinusoidal waveform.  
                                                      
1  TNI 01 0115 International Vocabulary of Metrology –  Basic and General Concepts and Associated Terms 
(VIM) and International Vocabulary of Legal Metrology (VIML) are part of the technical harmonisation 
compendium ‘Terminology in the field of metrology’, which is publicly available at www.unmz.cz.  Measure of a General Nature No  0111- OOP -C088- 18 
 
3 1.7 
accuracy class  
used to designate a current transformer whose current error and angle error do not exceed permitted 
values in prescribed operating conditions  
1.8 
transformer load  
the impedance of the secondary circuit expressed in ohms for a given power factor  The load is usually 
expressed as the apparent power in VA consumed at the stipulated po wer factor and at nominal 
secondary current.  
1.9 nominal load  
the load value upon which requirements for the stipulated accuracy are based  
1.10 nominal apparent output  
the value of the apparent output (in volt -amperes at a given power factor) that the transformer transfers 
to the secondary circuit at nominal secondary current and a connected nominal load 
1.11 maximum device voltage  
the maximum effective value of associated AC voltage for which the transformer is designed with 
respect to its insulation  
1.12 
nominal insulation level 
a combination of voltage values that characterises the transformer's insulation from the standpoint of its 
ability to resist electrical stress  
1.13 
nominal frequency  
the frequency value on which the requirements of this Measure  are based  
1.14 
nominal transient thermal current ( Ith) 
the effective primary current value that the transformer will withstand for one second during a short -
circuited secondary winding without being damaged; times other than one second can be used, e.g. 0.5 
s, 3 s, 5 s  
1.15 
nominal dynamic current ( Idyn) 
the peak value of primary current that the transformer will withstand without electrical or physical 
damage due to EM forces during a secondary winding short -circuit  
1.16 
nominal continuous thermal current  
the value of the current that can permanently flow through the primary winding without causing the 
prescribed heating value to be exceeded when a nominal load is connected to the secondary winding  Measure of a General Nature No  0111- OOP -C088- 18 
 
4 1.17 
excitation current  
the effective value of the current  flowing through the secondary winding of the current transformer when 
a sinusoidal voltage at nominal frequency is applied to the secondary terminals, the primary and all other 
windings being open  
1.18 
total error  
under steady state conditions, the effect ive value of the difference between instantaneous primary 
current values and instantaneous actual secondary current values multiplied by the nominal conversion; 
the positive sign of the primary and secondary current corresponds to agreed- upon terminal mark ings 
In general, the total error εc is expressed as a percentage of the effective values of the primary current 
according to the following formula:  
()∫− =εT
p sn
pc dtiiK
TI 02 1 100
(%) (2) 
where  Kn  ....... is the nominal current transformer conversion;  
Ip  ........ is the effective primary current;  
ip  ......... is the immediate primary current;  
Is  ......... is the immediate secondary current;  
T  ......... is the duration of one cycle.  
1.19 
nominal primary overcurrent (IPL)  
the value of the minimum primary current at which the total error of the current instrum ent transformer 
is greater than or equal to 10% at the nominal secondary load 
NOTE:  The total error should be greater than 10% in order to protect equipment powered by the instrument 
transformer from high currents under fault conditions.  
1.20 overcurrent number (FS)  
the ratio of the nominal primary overcurrent to the nominal primary current  
NOTE:  In the event that a short -circuit current flows through the primary winding of the current transformer, 
maximum safety will be provided to powered devices if the overcurrent number (FS) is small.  
1.21 limit secondary electromotive voltage  
the product of the overcurrent number, nominal secondary current and the vector sum of the nominal 
load and the secondary winding impedance  
2   Metrological requirements  
2.1 Normal operating conditions  
2.1.1 Ambient temperature  
Current transformers are classified into three categories, as shown in Table 1.  Measure of a General Nature No  0111- OOP -C088- 18 
 
5 Table 1 - Temperature categories  
Category  Lowest temperature (° C)  Highest temperature (° C)  
-5/+40  -5 +40 
-25/+40  -25 +40 
-40/+40  -40 +40 
NOTE:  Storage and transport conditions must also be considered when selecting a temperature category.  
2.1.2 Other operating conditions for indoor current transformers  
Other operating conditions that are considered are as follows:  
(a) the influence of solar radiation; may be neglected;  
(b) the influence of ambient air if it is not heavily contaminated by dust, smoke, corrosive gases, 
vapours or salts; may be neglected;  
(c) the effect of relative humidity may be neglected if the followin g conditions are met:  
 the average relative humidity measured over 24 hours does not exceed 95%;  
 the average water vapour pressure over 24 hours does not exceed 2.2 kPa;  
 the average relative humidity over the course of one month does not exceed 90%;  
 the average water vapour pressure over the course of one month does not exceed 1.8 kPa.  
Under these conditions, condensation of water vapour may occasionally occur.  
NOTE:  To ensure immunity to high humidity and condensation that could cause insulation bre akdown or corrosion 
of metal parts, a transformer designed for such conditions should be used.  
2.1.3 Other operating conditions for outdoor CIT  
Other operating conditions that are considered are as follows:  
(a) if the average ambient air temperature measur ed over a period of 24 hours does not exceed 35 ° 
C, it can be neglected;  
(b) solar radiation exceeding 1000 W/m2 (at noon on a clear day) must be taken into account;  
(c) the ambient air, if it is heavily contaminated by dust, smoke, corrosive gases, vapou rs or salts, 
must be taken into account;  
(d) wind pressure not exceeding 700 Pa (this value corresponds to a wind speed of 34 m/s) is not 
taken into account;  
(e) the presence of condensation or precipitation must be taken into account.  
2.2   Nominal values  of CIT parameters  
2.2.1   Nominal primary current values  
Single conversion transformers  
The standardised values of nominal primary currents are as follows:  
(10; 12.5; 15; 20; 25; 30; 40; 50; 60; 75) A  
and their decimal multiples or fractions.  Underlined values are preferred.  
Multiple conversion (winding) transformers  
The values given in Article 2.2.1 apply to the lowest nominal primary current values.  Measure of a General Nature No  0111- OOP -C088- 18 
 
6 2.2.2  Nominal secondary current values  
The nominal secondary current values are 1 A, 2 A and 5 A; the pre ferred values are 5 A and 1 A.  
NOTE:  For transformers that are intended to be delta- connected in a group, these nominal values divided by √ 3 
will also be standardised values.  
2.2.3  Nominal continuous thermal current  
Unless specified otherwise, the nominal continuous thermal current must be the nominal primary current 
(see Article 2.4.5).  
2.2.4  Nominal load values  
Nominal load values for instrument transformers up to 30 VA are as follows:  
(2.5; 5,0; 10; 15; 30) VA. Values above 30 VA can be selected as needed.  
For loads below 5 VA, a power factor of 1 is used, while for 5 VA and greater, a power factor of 0.8 is used.  
2.3 Standardised values for transient currents  
Current transformers with a primary winding consisting of a coil or a separate conductor must comply 
with the requirements of articles 2.3.1 and 2.3.2.  
2.3.1  Nominal transient thermal current ( Ith) 
The nominal transient thermal current ( Ith) must be determined for each transformer (see Article 1.14), 
and this value must be indicated on the nameplat e. 
2.3.2  Nominal dynamic current ( Idyn) 
The value of the nominal dynamic current ( Idyn) must be 2.5 times the nominal transient thermal current 
(Ith) under the defined conditions, and if different from this value must be indicated on the nameplate 
(see 1.1 5). 
2.4 Accuracy classes and permissible errors of current instrument transformers  
2.4.1  Determination of the accuracy class of current instrument transformers  
For current instrument transformers, the accuracy class is determined by the maximum permissible  
current error expressed as a percentage at the nominal current prescribed for the relevant accuracy class.  
2.4.2  Standardised accuracy classes  
Standardised accuracy classes for current instrument transformers are as follows:  
0.1, 0.2, 0.2S, 0.5, 0.5S, 1.  
2.4.3  Permissible current errors and angle errors for current instrument transformers  
For classes 0.1, 0.2, 0.5 and 1, current error and angle error at rated frequency must not exceed the values in Table 2 when the secondary load is between 25% and 100% of  the nominal load. 
For classes 0.2S and 0.5S, current error and angle error at nominal frequency must not exceed the values 
in Table 2 when the secondary load is between 25% and 100% of the nominal load. 
The secondary load used for test purposes for all ac curacy classes must have an inductive power factor 
of 0.8, except when the load is less than 5 VA; in this case, a power factor of 1 must be used.  
The test load must never be less than 1 VA.  Measure of a General Nature No  0111- OOP -C088- 18 
 
7 NOTE:  Generally permissible current errors and angle errors are g iven for arbitrary locations of an external 
conductor in the air at a distance greater than that required for the air separation distance at the highest voltage for 
the device ( Um see Table 4).  
Table 2 - Maximum permissible current errors and angle errors for current instrument 
transformers 
Accuracy 
class  ± current error (ratio) as a 
percentage of the nominal 
current specified in the following 
row ± current error as a percentage of the nominal current 
specified in the following line  
Minutes  Centiradians  
5 20 100 120 5 20 100 120 5 20 100 120 
0.1 0.4 0.2 0.1 0.1 15 8 5 5 0.45 0.24 0.15 0.1 
0.2 0.75 0.35 0.2 0.2 30 15 10 10 0.9 0.45 0.3 0.3 
0.5 1.5 0.75 0.5 0.5 90 45 30 30 2.7 1.35 0.9 0.9 
1.0 3.0 1.5 1.0 1.0 180 90 60 60 5.4 2.7 1.8 1.8 
Table 3 - Maximum permissible current and angle errors for special -purpose current 
instrument transformers  
Accuracy 
class  ± current error (ratio) as a 
percentage of the nominal 
current specified in the 
following row  ± current error as a percentage of the nominal current 
specified in the following line  
Minutes  Centiradians  
1 5 20 100 120 1 5 20 100 120 1 5 20 100 120 
0.2S 0.75 0.35 0.2 0.2 0.2 30 15 10 10 10 0.9 0.45 0.3 0.3 0.3 
0.5S 1.5 0.75 0.5 0.5 0.5 90 45 30 30 30 2.7 1.35 0.9 0.9 0.9 
2.4.4 Extended load range  
For all transformer accuracy classes whose permissible errors are given in tables 2 and 3, an extended 
load range may be defined.  In this case, these permissible errors must apply to loads in the range of 1 
VA up to the nominal value at a power factor of 1.The maximum nominal load is limited to 15 VA.  
2.4.5 Extended current range 
Current transformers of accuracy classes 0.1 to 1 may be designated as extended current range 
transformers if they meet the following requirements:  
a) the nominal continuous thermal current must be the nominal extended primary current express ed 
as a percentage of the nominal primary current;  
b) the permissible current errors and angle errors specified at 120% of the nominal primary current 
in Table 2 must be ensured up to the nominal extended primary current.  
The extended primary current is to  be expressed as a percentage of the nominal value of the primary 
current (e.g. 150% I N). Measure of a General Nature No  0111- OOP -C088- 18 
 
8 3 Technical requirements  
3.1 Insulation requirements  
These requirements apply to all CIT types.  
3.2 Nominal insulation levels for the primary winding  
The highest volt age for the device is selected as the nearest standardised value Um greater than or equal 
to the maximum voltage of the system in which the device is installed.  The standardised values U m must 
be selected from Table 4.For CITs installed in normal ambient conditions related to insulation, U m must 
be at least equal to the maximum voltage of the grid U sys. For a device installed outside range of normal 
ambient conditions related to insulation, the value Um may be selected higher than the nearest 
standardised v alue Um, equal to or greater than U sys according to special needs.  For plug- in CITs without 
primary conductor insulation, Um = 0.72 kV. 
NOTE:  For example, choosing U m higher than the nearest standardised value U m greater than or equal to U sys when 
the instrument transformer is to be installed at an altitude greater than 1,000 metres a.s.l. to compensate for the 
drop in the withstand voltage of the external insulation.  
Table 4 - Prescribed primary terminal insulation levels for instrument trans formers  
Maximum device 
voltage Um 
(effective value)  
kV Nominal power -
frequency withstand 
voltage  
(effective value)  
kV Nominal atmospheric 
impulse withstand 
voltage  
(peak value)  
kV Nominal switching 
impulse withstand 
voltage  
(peak value)  
kV 
0.72 3 --- --- 
1.2 6 --- --- 
3.6 10 20 --- 
40 --- 
7.2 20 40 --- 
60 --- 
12 28 60 --- 
75 --- 
17.5 38 75 --- 
95 --- 
24 50 95 --- 
125 --- 
36 70 145 --- 
170 --- 
52 95 250 --- 
72.5 140 325 --- 
100 185 450 --- 
123 185 450 --- 
230 550 --- 
145 230 550 --- 
275 650 --- 
170 275 650 --- 
325 750 --- 
continued  
 Measure of a General Nature No  0111- OOP -C088- 18 
 
9 Table  4 – continued  
Maximum device 
voltage Um 
(effective value)  
kV Nominal power -
frequency withstand 
voltage  
(effective value)  
kV Nominal atmospheric 
impulse withstand 
voltage  
(peak value)  
kV Nominal switching 
impulse withstand 
voltage  
(peak value)  
kV 
245 395 950 --- 
460 1,050  --- 
300 395 950 750 
460 1,050  850 
362 460 1,050  850 
510 1,175  950 
420 570 1,300  950 
630 1,425  1,050  
550 630 1,425  1,050  
680 1,550  1,175  
800 880 1,950  1,425  
975 2,100  1,550  
3.3. Requirements for secondary windings insulation and external insulation  
3.3.1 Requirements for insulation between winding sections  
For primary and secondary windings divided into two or more sections, the insulation between the  
sections must withstand a effective nominal transient power -frequency AC voltage of 3 kV. 
3.3.2 Secondary winding insulation requirements  
The insulation of secondary windings must withstand a nominal transient power -frequency voltage AC 
of 3 kV.  
3.3.3 Coil insulation requirements  
The nominal withstand voltage of coil insulation must be 4.5 kV (peak value).  
For some types of transformers, lower values may be allowed in accordance with the test procedure in 
Article 5.10.  
NOTE:  The test procedure may cause the waveform to be highly distorted.  
3.3.4 External insulation requirements in the event of soiling  
For current transformers for outdoor use with a ceramic insulator sensitive to soiling, Table 5 lists the required insulation distances measured across the insulator surface for individual degrees of soiling.  
Table 5 - Insulation distances in the event of soiling  
Degree of soiling  Minimum nominal surface 
distance  
mm/kV1) Surface to arcing distance ratio  
I low  
II medium  16 
20 ≤3.5 
III high  
IV very high  25 
31 ≤4.0 
1)The ratio of surface distance between phase and ground to the device's highest effective voltage.  Measure of a General Nature No  0111- OOP -C088- 18 
 
10 NOTES:  
1.  It is found that the quality of the surface insulation is greatly influenced by the shape of the insulator.  
2.  In very lightly soiled areas, specific insulation distances below 16 mm/kV can be used down to a limit 
value of 12 mm/kV.  
3.  In cases of exceptionally heavy soiling, even a specific insulation value of 31 mm/kV may not suffice.  
Depending on operating experience or laboratory te sts, an even higher specific insulation distance may be 
used.  In some cases insulators can be washed.  
3.3.5 Altitude above sea level  
For installations more that 1,000 m above sea level, the arcing distance determined for normal reference 
atmospheric condi tions must be recalculated by multiplying the withstand test voltage required for a 
given installation site by a correction factor k  according to the following formula. 
Factors are calculated according to the following formula:  
k = em(H − 1000)/8150 (3) 
where  H  is altitude above sea level (m);  
m = 1 for grid frequency and an atmospheric impulse;  
m = 0.75 pro a switching impulse. 
3.4 Partial discharge requirements  
Partial discharge requirements are for current transformers with U m ≥ 7.2 kV. Partial discharge levels 
must not exceed those in Table 6.  
Table 6 - Test voltages for measuring partial discharges and permissible levels 
Network ground type  Test voltage for partial 
discharge measurement  
(effective value)  
kV Permissible partial 
discharge levels  
pC 
Insulation type  
Windings 
submerged 
in oil  Dry 
insulation  
Network with ground node  
(ground fault coefficient ≤ 1.4)  Um 10 50 
1.2 Um/√3 5 20 
Grid with insulated or non -effective ground 
node  
(ground fault coefficient > 1.4)  1.2 Um 10 50 
1.2 U m/√3 5 20 
NOTES:  
1.  If the grounding type is not defined, the values for an insulated or non- effectively grounded network 
apply.  
2.  Permissible partial discharge levels also apply for measurements with a frequency other than the nominal 
frequency.  Measure of a General Nature No  0111- OOP -C088- 18 
 
11 4 Measuring instrument markings  
4.1 Terminal markings  
Terminal markings must identify:  
a) primary and secondary windings;  
b) winding sections, if any;  
c) relative polarity of windings and winding sections;  
d) centre taps, if any.  
4.2 Marking method  
Terminals  must be clearly and indelibly marked either on their surface or in their immediate vicinity.  
Markings must consist of letters followed by numbers, or preceded if necessary.  Capital block letters of 
the alphabet must be used.  
4.3 Markings used  
Preferred cu rrent transformer terminal markings are shown in Figure 1.  
Primary terminals  
 
 
 
Secondary 
terminals   
a) Single -conversion transformer   
b) Transformer with a centre tap on 
the secondary winding  
Primary terminals  
 
 
 
 
Secondary 
terminals   
 
c) Transformer with the primary 
winding configured in two sections for 
serial or parallel connection   
d) Transformer with two secondary 
windings; each has its own magnetic 
core.(Two alternative markings for 
secondary terminals.)  
Figure 1 - Terminal markings  
4.4 Polarity indication  
All terminals marked P1, S1 and C1 must have the same polarity at the same time.  
4.5 Information on the nameplate  
All current transformers must have a nameplate bearing at least the following information:  
a) the manufacturer's name or t rade mark;  
b) year of manufacture and serial number and type designation;  
Measure of a General Nature No  0111- OOP -C088- 18 
 
12 c) nominal primary and secondary currents, i.e.:  
Kn = Ipn /Isn A (e.g. K  = 100 A/5 A),  
where Ipn a I sn is the transformer's nominal primary/secondary current;  
d) nominal frequency (e .g. 50 Hz);  
e) nominal load and the corresponding accuracy class together with the additional information 
specified in this measure (see Article 2.4.5);  
f) maximum device voltage (e.g. 1.2 kV or 145 kV);  
g) nominal insulation level (e.g. 6/20 kV or 275/650 kV);  
h) nominal transient thermal current ( Ith) and nominal dynamic current if it is not 2.5 times the 
nominal transient thermal current (e.g. 13 kA or 13/40 kA);  
i) insulation class, if different from Class A;  
j) temperature category;  
k) weight in kg.  
NOTE:  
Items f) and g) can be combined into one marking (e.g. 1.6 kV or 145/275/650 kV).  
If several classes of insulating materials are used, the one that limits winding warming is given.  In the case of 
transformers with two windings, each winding and its corresponding terminals are marked.  
All information must be indelibly marked on the current transformer or on a nameplate attached to the transformer.  
4.6 Additional requirements for information on current instrument transformer 
nameplates  
The marking plat e must contain relevant information pursuant to Article 4.5.The accuracy class and the 
overcurrent number must be indicated after the nominal load (e.g. 15 VA; class 0.5; FS 10).Current 
transformers with an extended current range (see 2.4.5) must have this information immediately after 
the class information (e.g. 15 VA; class 0.5; ext.150%).  
NOTE The label may contain information regarding several load and accuracy class combinations that the 
transformer can comply with (e.g. 15 VA, class 0.5 -  30 VA, class  1) and in this case non -standardised load values 
that can be used (e.g. 15 VA, Class 1 -  7 VA, Class 0.5 in accordance with the note for Article 2.4.4).  
5 Measuring instrument type approval  
The type approval process for instrument transformers includes th e following tests and activities:  
5.1 Transient current test  
For the test involving transient thermal current I th, the transformer must be at a starting temperature 
between + 10 °C and + 40 °C. This test must be performed with a shorted secondary winding a nd a 
current of I for t such that the product of I2 t will not be less than I2th and time t will be between 0.5 s 
and 5 s.  
The dynamic test must be carried out with shorted secondary windings and with a peak current value 
not less than the nominal dynamic current Idyn at least the first peak.  This dynamic test may be combined 
with the aforementioned thermal test performed so that the first highest peak of the current in the test 
will not be less than the nominal dynamic current I dyn. The transformer has passed the test if, after cooling 
to an ambient temperature between +10 °C and +40 °C, it meets the following requirements:  
a) it is not visibly damaged; 
b) its demagnetisation errors do not differ from the errors recorded before the tests by more than half 
of the limit errors in its accuracy class;  Measure of a General Nature No  0111- OOP -C088- 18 
 
13 c) it passes dielectric tests pursuant to Articles 5.10, 5.11 and 5.12 with test voltages reduced to 90% 
of the prescribed values;  
d) inspection of insulation next to the lead surfaces reveals no significant damage (e.g. charring).  
Inspection pursuant to d) is not required if the current density in the primary winding corresponding to 
the nominal transient thermal current I th does not exceed 180 A/mm2 in the case of copper windings, or 
120 A/mm2 in the case of  aluminium windings. 
5.2 Temperature rise test  
For this test, it is stipulated that the transformer has reached a steady state if the temperature increment 
per hour is not greater than 1 K. The ambient temperature at the test site must be between +10 °C an d 
+30 °C. In this test, the transformer must be assembled in the same way as it will be in operation.  
Winding temperature rise must be determined from changes in resistance; for windings with very low 
resistance, thermocouples can be used.  The temperature rise of parts other than windings can be 
measured using thermometers or thermocouples.  The temperature rise of windings, magnetic circuits or 
any other parts must not exceed the values in Table 7.  
Table 7 – Temperature rise limits for different parts, materials and dielectrics of CIT  
Part of the instrument transformer  Temperature rise limits (K) 
1.  Oil-filled instrument transformers − oil in the top layer - 
oil in the top layer, hermetically sealed − centre of winding -  centre of winding, hermetically sealed− other 
metal parts in contact with oil  50 – 60 – 65 55 − as for windings  
2.  Instrument transformers with solid or gas insulation − 
windings (average value) in contact with insulating materials according to the following classes:  Y − A − E − 
B − F − H − other metal parts in contact with the above material classes  
45 − 60 − 75 – 85 − 110 − 135 − as 
for windings  
3.  Connections, screw or equivalent − bare copper, bare 
copper alloy or bare aluminium alloy   
• in air  50 
• in SF6  75 
• in oil − silver plated or nickel plated  60 
• in air  75 
• in SF6  75 
• in oil − tinplate  60 
• in air  65 
• in SF6  65 
• in oil  60 
5.3. Impulse voltage primary winding test  
The test voltage must be applied between the primary winding terminals (interconnected) and ground.  
The frame, case (if present) and core (if it is to be grounded) and all secondary winding terminals must 
be grounded. Pulse tests generally consist of applying reference and test impulses.  The reference impulse 
voltage must have an amplitude between 50% and 75% of the nominal test voltage.  The peak value and 
the shape of the voltage pulse must be recorded during the test. Proof of failure is given by the change 
in the shape of the reference and test voltage pulses.  For fault detection, current s flowing to ground 
during the test can be recorded to supplement voltage recording.  Measure of a General Nature No  0111- OOP -C088- 18 
 
14 5.3.1 Atmospheric impulse test  
The test voltage must have an appropriate value pursuant to Table 4 according to the highest voltage for 
the device and the specified insula tion level.  
5.3.1.1 Windings with U m < 300 kV  
The test must be performed using both positive and negative polarity impulses.  Fifteen consecutive 
impulses of each polarity are applied with no correction for atmospheric conditions. The transformer 
has passed  the test if for both polarities:  
a) non-self-restoring internal insulation was not breached;  
b) no arc occurred along non- self-restoring external insulation.  This is confirmed via five 
consecutive withstand impulses after the last arc;  
c) no more than two arcs occurred along non- self-restoring external insulation;  
d) no other evidence of insulation fault was found (for example no changes in shape occurred during 
the course of recorded values).  
If arcs have occurred and evidence cannot be provided during the test that they occurred in self -restoring 
insulation, the instrument transformer must be removed and inspected after the dielectric tests have been completed. If damage to non- self-restoring insulation is observed, the instrument transformer has failed 
the test.  
NOTE:  The application of 15 positive and 15 negative impulses is stipulated for external insulation testing.  If the 
manufacturer and the customer have agreed on additional testing of external insulation, the number of atmospheric 
impulses may be r educed to three impulses of each polarity without correction for atmospheric conditions.  
5.3.1.2 Windings with U m ≥ 300 kV  
The test must be performed using both positive and negative polarity. Three consecutive impulses of 
each polarity are applied with no  correction for atmospheric conditions.  
The transformer has passed the test if:  
a) no arcs occurred;  
b) there is no other evidence of insulation faults.  
5.3.2  Switching impulse test  
The test voltage must have the appropriate value pursuant to Table 4 according to the highest voltage 
for the device and the specified insulation level.  
The test must be performed using positive polarity. Fifteen consecutive impulses of each polarity with 
correction for atmospheric conditions are applied to the transformer. For outdoor transformers, the test 
must be carried out in rain (see 5.4).The transformer has passed the test if:  
a) non-self-restoring internal insulation was not breached;  
b) no arc occurred along non- self-restoring external insulation;  
c) no more than t wo arcs occurred along non- self-restoring external insulation;  
d) no other evidence of insulation fault was found (for example no changes in shape occurred during 
the course of recorded values).  
If arcs have occurred and evidence cannot be provided during the test that they occurred in self -restoring 
insulation, the CIT must be removed and inspected after the dielectric tests have been completed.  If 
damage to non- self-restoring insulation is observed, the CIT has failed the test.  
NOTE:  Impulses during which arcs occurred to the walls or ceiling of the laboratory are not taken into account.  Measure of a General Nature No  0111- OOP -C088- 18 
 
15 5.4. Outdoor transformer rain test  
For windings with U m < 300 kV, the test must be carried out with power -frequency AC voltage and the 
test voltage in Table 4 as a function of the maximum voltage for the device, corrected for atmospheric 
conditions.  
For windings with U m ≥ 300 kV, the test must be carried out wit h positive switching impulses and the 
test voltage in Table 4 as a function of the maximum voltage for the device and at the nominal insulation 
level.  
5.5 Electromagnetic compatibility (EMC) test -  radio interference voltage (RIV) 
measurement  
RIV requirements apply to instrument transformers with U m ≥ 123 kV that will be installed in air -
insulated substations.  
Because interfering RF voltages may be affected by fibres or dust deposited on insulators, they may be 
wiped with a clean cloth prior to the start of  measurement.  
The following procedure must be followed:  
The instrument transformer with accessories must be dry and clean and at approximately the same 
temperature as the laboratory where the test is performed.  The test is performed under the following 
atmospheric conditions:  
Ambient temperature:10 °C to 30 °C  
Atmospheric pressure:(0.870·105 to 1.07·105) Pa 
Relative humidity:45% to 75%  
The test leads and their ends must not be a source of radio- frequency interference.  
In order to avoid interfering discharge s from the primary terminals, they must be appropriately shielded 
by imitating service shielding.  It is recommended to use a length of pipe with a spherical end.  
 
 
Measure of a General Nature No  0111- OOP -C088- 18 
 
16 Legenda  Legend  
zkušební transformátor  test transformer  
zkoušený předmět  tested item  
filtr filter  
svorka s  ochranou proti vzniku korony  terminal with protection against corona formation  
měřicí souprava se vstupním odporem RM measuring equipment with input resistance RM 
ZS, CS L1, R1, R2 viz CISPR 18 -2 ZS, CS L1, R1, R2 see CISPR 18 -2 
Figure 2 - Electromagnetic compatibility test arrangement  
As shown in Figure 2, the test voltage is applied between one of the primary winding terminals of the 
test item ( Ca) and ground.  The frame, cover (if any), core (if it is intended to be grounded) and one 
terminal of each secondary winding are grounded.  
The measuring circuit must be tuned in the 0.5 MHz to 2 MHz band with measurement frequency recording.  Results are expressed in microvolts.  
The impedance between the test lead and ground, ( Z
S + (R1 + R2 // RM)) in Figure 3, must be 300 Ω ± 40 
Ω with a phase angle not exceeding 20° at the measurement frequency. 
Capacitor CS may also be used instead of filter ZS; sufficient capacity is 1,000 pF.  
Filter Z must have a large impedance at the measuring freq uency to separate the power -frequency source 
from the measuring circuit. A suitable value for this impedance at the measuring frequency can be found 
from 10,000 Ω to 20,000 Ω. The background noise level of high- frequency interference (RF interference caused by an external field 
and a high -voltage transformer) must be at least 6 dB (preferably 10 dB) below the given level of radio 
interference.  
The test voltage is applied between one of the primary winding terminals of the test item ( C
a) and 
ground. The fram e, cover (if any), core (if it is intended to be grounded) and one terminal of each 
secondary winding are grounded.  
Prior to the measurement itself, a voltage of 1.5 × Um/√3 is applied and maintained for 30 seconds. The 
voltage is then reduced to 1.1 × U m/√3 for approximately 10 seconds, and is maintained at this value for 
30 seconds prior to the actual RF interference measurement.  
The instrument transformer is deemed to have passed this test if the RF interference does not exceed 
2500 μV at 1.1 U m/√3. 
5.6 Accuracy tests  
Type tests to verify the requirements of Article 2.4.3 for transformers of classes 0.1 to 1 must be 
performed for each of the current values in Table 2 at 25% and 100% of the nominal load (provided that 
1 VA is the minimum load).Transformers  with an extended current range greater than 120% must be 
tested at the nominal extended primary current instead of at 120% of nominal current.  
In the case of extended load range, the accuracy test must be performed for 1 VA and for 100% of the 
nominal loa d at a power factor of 1.The maximum rated load in this case is limited to 15 VA.  
5.7 Terminal markings check  
This test is performed pursuant to Article 4.2.  
5.8 Primary winding AC test  
The test voltage must have the appropriate value (according to Table 4) depending on the maximum 
voltage for the device.  The duration of the test must be 60 seconds. The test voltage must be applied to Measure of a General Nature No  0111- OOP -C088- 18 
 
17 the shorted primary winding and ground. The short -circuited secondary winding, the frame, the casing 
(if any) and the core (if it has a separate ground terminal) must be grounded.  
5.9   AC test of the secondary winding and between winding parts  
A 3 kV test voltage must be applied for 60 seconds between the shorted terminals of each winding 
section or each secondary winding and ground.  
5.10   Inter -turn insulation surge test  
An inter -turn insulation surge test must be performed using one of the methods below. Unless otherwise 
agreed, the manufacturer chooses one of these methods.  
Method A:  
When the secondary windings are disconn ected (or connected to a high -impedance device that 
records the peak value), a sinusoidal current of frequency between 40 Hz and 60 Hz is applied to the 
primary winding for 60 seconds at an effective value corresponding to the nominal primary current 
(or t he nominal increased primary current [see Article 2.4.5] if this current comes into 
consideration).The current used must be limited if a peak test voltage of 4.5 kV is reached before the nominal current (or nominal increased current) is reached.  
Method B:  
If the primary winding terminals are open, the specified test voltage of 50 Hz to 400 Hz must be connected to the terminals of each secondary winding for 60 seconds, provided that the effective 
value of the secondary current does not exceed the nominal sec ondary current (or nominal increased 
current).If at this frequency the peak voltage reached at the nominal secondary current (or increased 
current) is less than 4.5 kV, then this voltage is considered to be the test voltage. If the frequency 
exceeds double  the nominal frequency, the test period may be reduced to less than 60 seconds 
according to the following relationship:  
60 )( × =frekvence zkušebnífrekvence jmenoviték dvojnásobes zkoušky trvání , 
but to no less than 15 seconds.  
5.11   Partial discharge measurement  
5.11.1   Test circuit and measuring equipme nt 
The measuring equipment must measure the apparent charge Q  expressed in pico coulombs (pC).It must 
be calibrated after it is connected to the test circuit.  Broadband equipment must have a minimum 
bandwidth of 100 kHz with an upper frequency not exceeding 1.2 MHz. Narrowband equipment must 
have its resonant frequency within 0.15 MHz to 2 MHz.  A range of 0.5 MHz to 2 MHz is recommended, 
but if feasible, measurements will be made at the frequency that provides the greatest sensitivity.  
Sensitivity must allo w detection of partial discharges with an amplitude of 5 pC.  
NOTES:  
1. Interference must be significantly lower than the indicated sensitivity.  Known impulses caused by external 
interference are not considered.  
2. Bridge connection can be used to suppress external interference.  
3. If equipment allowing electronic interference suppression is used, it must be proven by means of changes to 
its parameters that it allows the detection of repeated impulses.  Measure of a General Nature No  0111- OOP -C088- 18 
 
18 5.11.2  Partial discharge measurement procedure  
After pre -test stress using Method A or Method B, the test voltage is increased to the test voltage value 
for partial discharge measurement in Table 6 and partial discharge measurements are made at this level 
for 30 seconds.  The partial discharge level must not exceed the values in Table 6.  
Method A:  
The voltage level is reached while the voltage is being reduced after the applied power -frequency 
voltage test.  
Method B:  
Partial discharge measurements are made after the applied power -frequency voltage test.  The vo ltage 
is increased to 80% of the test voltage for the applied power -frequency voltage test, allowed to remain 
at that level for at least 60 seconds and reduced to the partial discharge voltage without interruption.  
Unless otherwise stipulated, the manufact urer chooses one of these methods.  The test method chosen 
must be specified in the test report.  
6   Initial verification  
The following tests must be carried out during the verification of current instrument transformers:  
a) a technical inspection and check  that terminals are marked correctly;  
b) determination of the transformer's current and angle errors.  
6.1 Required tools  
The following test equipment is used to test transformers:  
6.1.1  Measuring set -up 
The measuring set -up consisting of a reference measur ing device for evaluating the difference in errors 
between the reference and the tested CIT, a reference current instrument transformer or a reference current comparator for current transformer loads, auxiliary measuring instruments for measuring 
current, frequency and distortion, and of regulated power circuitry. 
6.1.2 Set -up for demagnetising current instrument transformers  
A set -up comprising a power supply with regulation, an ammeter or a current measuring shunt, a voltage 
divider with a voltmeter to me asure the peak and mean voltage or an oscilloscope  
6.1.3. Set -up to determine additional supply cable resistances  
A set -up that allows measurement with an accuracy of 3 or better (e.g. a digital multimeter with four -
terminal resistance measurement, i.e. a 4-wire connection).  
6.1.4 Current instrument transformer loads  
Loads with a power factor of cos 
β = 0.8 or cos β = 1 must be used, specified for the given frequency, 
allowing the nominal value, gi ven by the combination of the actual load, the impedance of the measuring 
device and the supply cables, to be set with the appropriate error.  Current instrument transformer loads 
(see section 2.2.4) with a value of Z <5 VA must have a power factor of cos β = 1.For the measurement 
of errors of transformers with extended load range, a load with power factor cos β = 1 up to Z ≤ 15 VA 
must be used.  Measure of a General Nature No  0111- OOP -C088- 18 
 
19 6.1.5 Power supplies  
Power supplies with harmonic curr ent control over the required range must be used, with appropriate 
adjustment accuracy, stability and distortion of less than 5%.  
6.1.6  Distortion measuring instrument  
A distortion measuring instrument is used to monitor the current curve so that the distortion is less than 
5%. 
6.2 Conditions during tests  
Current instrument transformers are tested at the nominal frequency with a maximum deviation of ± 
1%, at a current harmonic whose distortion factor does not exceed 5%, an ambient temperature of +15 
°C to +25 °C, relative air humidity of no more than 75% and an external magnetic field up to 1 mT. 
6.3 Description of tests  
6.3.1  Physical damage  
Current instrument transformers are checked for physical damage, that nameplate information is 
complete, correct  and legible, and that terminals are properly connected.  
6.3.2  Correct marking of terminals  
When checking whether terminals are marked correctly, the tested and reference transformer are 
connected in the measuring set -up so that the primary current in the windings of both transformers flows 
in the same direction (this corresponds the P2 or L terminal of the reference being connected in series with the P1 or K terminal of the tested CIT or vice versa).The secondary terminals of the two 
transformers are conne cted to identically marked measuring equipment terminals.  If errors can be 
measured by the measuring equipment when the primary current is set to 10% I
1N, the terminals are 
marked correctly.  Otherwise, the CIT is excluded from further testing. 
6.4 Demagnet isation of the CIT  
6.4.1  Demagnetisation  
Current instrument transformers to be tested must be demagnetised prior to measurement by any of the methods specified in Article 6.4.2.a) or 6.4.2.b) if it is evident that the CIT has been magnetised prior 
to measurement.  In other cases, demagnetisation is only performed if errors measured for the CIT do 
not correspond to required values.  
6.4.2  Demagnetisation procedure  
a) The primary or secondary winding of the CIT (usually the winding with the highest number of turns) is connected to a current source with a harmonic waveform (implemented for example by a voltage 
source and a series resistor) and nominal frequency. The other windings must be disconnected. The 
power supply current is increased slowly until it re aches the nominal value of the winding used, or 
until the peak voltage value on the open winding with the highest number of turns, measured by a 
peak voltmeter, reaches 3 kV for current transformers.  The power supply current is then slowly and 
smoothly dec reased to zero.  If it is not possible to guarantee an ideally continuous decrease of the 
demagnetisation current (e.g. using a regulating transformer), it is necessary to configure the 
demagnetisation circuit so that the last step to zero current is not gr eater than 0.1% of the maximum 
current used during demagnetisation.  
NOTE:  When measuring voltage, the measuring winding must not be loaded by current greater than 0.1% of the 
nominal value.  Measure of a General Nature No  0111- OOP -C088- 18 
 
20 b) The CIT to be tested is connected as in Article 6.4.2(a).The su pply current is slowly increased as 
long as the mean voltage measured at any other winding keeps increasing (e.g. if a 10% increase in 
magnetising current corresponds to an increase in the mean induced voltage greater than 1%), or 
when the peak voltage val ue (or the magnitude of the demagnetising current) does not reach values 
as in Article 6.4.2(a).Subsequent steps are the same as in Article 6.4.2(a).  
NOTE:  The state where the ferromagnetic working point moves along the hysteresis loop boundary can also be  
determined by means of an oscilloscope, when the area of the half -wave of the induced voltage does not change 
significantly when the magnetising current increases.  
6.4.3  Demagnetisation of multi -core transformers  
For multi -core transformers, each core must be demagnetised.  
6.4.4  Demagnetisation of the reference transformer  
The reference CIT in the measuring set -up must be demagnetised during the test after every sudden 
current interruption, or if results indicate that it may be magnetised.  
6.5 Determination of current and angle errors of current instrument transformers  
6.5.1  Determination of errors  
The basic arrangement for determining the error of a current instrument transformer is shown in Figure 3. 
Current and angle errors are read on the se t-up's measuring device, and if needed corrected for errors in 
the reference and the measuring equipment.  
 
 
If the errors of the reference transformer are known, the transformer under measurement is corrected 
according to the following relationship  relationship:  
εIX = εIN + εIM , δIX = δIN + δIM,(4) 
where  εIX and δ IX are the errors of the transformer under measurement (%; '  ), 
εIN and δ IN are the errors of the reference transformer (%; ' ), 
εIM and δ IM are system data for error evaluation (%; ' ).  
The errors of current instrument transformers are determined first at the maximum value of the 
measuring range (e.g. 120% I 1N).Then lower current values are used, according to Table 2 or Table 
3.The reason is that the transformer can be demagnetised during  measurement.  Permissible CIT error 
limits at prescribed measuring points of accuracy class 0.1; 0.2; 0.5 and 1 are shown in Table 2, and for 
CIT accuracy classes of 0.2S and 0.5S in Table 3.  
Transformer errors are measured at 25% of the nominal load and a t the nominal load.  The secondary 
load used for test purposes for all accuracy classes must have an inductive power factor of 0.8, except 
when the load is less than 5 VA; in this case, a power factor of 1 must be used.  
 
 
 
  
  
 
 
kN 
 
 
 
I1 
I2X 
 I2N 
TESTED  
CIT 
REFERE
 
CURREN
T 
 
KN 
LN 
lN 
SYSTEM FOR 
EVALUATING 
CIT ERRORS  
P1 
P2 
LOAD  
S2 
S1 
I 
I 
P 
Figure 3 - Basic arrangement for determining current instrument transformer errors  Measure of a General Nature No  0111- OOP -C088- 18 
 
21 If the transformer has an extended load range, transformer errors at 1 VA and nominal load are measured.  
For the measurement of errors of transformers with extended load range, a load with power factor cos 
β = 1 up to Z ≤ 15 VA is used. The maximum rated load in this case is limited to 15 VA.  
6.5.2  Extended range current transformer errors  
For extended range transformers, current and angle errors are determined at the maximum value of the 
extended range nominal current (instead of at 120% I1N).The measured errors must not exceed the values 
applicable to 120% I 1N. 
6.5.3  Determining multi -core transformer errors 
In the case of current instrument transformers with two or more cores, current and angle errors 
corresponding to the windings (transformers) on the individual cores are determined sequentially, with 
the windings that are not being tested short -circuited.  Errors must be within permissible errors pursuant 
to Table 2 or Table 3.  
6.5.4 Determination of errors for transformers with a split magnetic circuit  
In the case of CIT with a split magnetic circuit, it is necessary that it has been sealed and secured 
properly.  
6.5.5  Determination of errors for multiple conversion transformers  
For multiple conversion current transformers, current and angle errors are d etermined for all nominal 
conversions and for primary current values in Table 2 or Table 3 and the CIT type.  When testing in-
service CITs (especially VHV), it is permissible to determine current and angle errors only for the 
conversion for which the CIT is  connected.  
6.5.6  Requirements for setting primary current and load  
The primary current set at the individual measured points must be guaranteed with an error not exceeding 0.5% of the nominal current in the range of measured currents 120% to 20% and 0.3% of the nominal 
current in the range of measured currents 5% to 1%.Errors in the absolute value of loads for CITs must 
not exceed 3% of the nominal value. Errors in real and imaginary components of general -type loads 
must not exceed 3% of nominal values.  
6.5.7  Errors in current transformers with accessories  
The maximum permissible current and angle errors must not be exceeded for CITs with connected 
accessories if they are an integral part of the transformer.  
6.6 Determination of current and angle errors of combined instrument transformers  
6.6.1  Requirements for combined transformer current errors  
For combined current and voltage operating transformers, the current transformer must comply with the conditions specified in Article 6.5, depending on design. 
6.6.2  Transformer interaction  
For combined instrument transformers, the interaction of both transformers must be determined when 
measuring errors:  
a) The effect of the current transformer on the voltage transformer;  
b) Thee effect of the voltage transformer on the current transformer. Measure of a General Nature No  0111- OOP -C088- 18 
 
22 6.6.3  Procedure used to determine transformer interaction  
a) The effect of the current transformer under test on the voltage transformer under test is determined 
by determining the voltage and angle error of the tested voltage  transformer:  
 With the primary terminals of the current transformer disconnected;  
 At a primary current of 120% of  I1N (or at the extended range current) and at 25% and 100% of 
the nominal secondary load Z N. 
b) The effect of the voltage transformer under test on the current transformer under test is determined by determining the voltage and angle error of the tested current transformer:  
 With the primary terminals of the voltage transformer disconnected;  
 At a primary voltage of 120% U
1N and at 25%  and 100% of the nominal secondary load. 
6.6.4  Permissible errors due to interaction  
The detected current, voltage and angle errors of a combined measuring transformer due to interaction must comply with the conditions specified in Article 6.5 for separate  error detection.  
7   Subsequent verification  
Subsequent verification is carried out in the same way as the initial verification in chapter 6.  
8   Measuring instrument check  
When examining measuring instruments pursuant to Section 11a of the Metrology Act at the request of 
a person who may be affected by an incorrect measurement, please proceed according to Chapter 7.The 
maximum permissible error used is 1.25 times the maximum permissible errors pursuant to Chapter 7.  
9   Notified standards  
For the purposes of specifying the metrological and technical requirements for measuring instruments 
and specifying the testing methods for their type approval and verification arising from this general 
measure, the CMI shall notify Czech technical standar ds, other technical standards or technical 
documents of international or foreign organisations, or other technical documents containing more 
detailed technical requirements (hereinafter referred to as ‘notified standards’).The CMI shall publish a 
list of these notified standards attached to the relevant measures, together with the general measure, in 
a manner accessible to the public (on www.cmi.cz ). 
Compliance with notified standards or parts thereof is considered, to the extent and under the conditions 
stipulated by a general measure, to be compliance with the requirements stipulated by this measure to 
which these standards or parts thereof apply.  
Compliance with notified standards is one way of demonstrating complianc e with the requirements.  
These requirements may also be met by using another technical solution guaranteeing an equivalent or 
higher level of protection of legitimate interests.  
II. 
G R O U N D S 
Pursuant to Section 14(1)(j) of the Metrology Act, the CMI has issued this Measure of a General Nature toward  the implementation of Section 6(2), Sec tion 9(1) and (9), and Section 11a(3) of the Metrology Measure of a General Nature No  0111- OOP -C088- 18 
 
23 Act, laying down metrological and technical requirements for specified measuring instruments and tests 
for type approval and verification of specified measuring instruments -  'current instrument transformers'. 
Decree No 4.1.4 specifying measuring instruments for mandatory verification and measuring instruments subject to type approval, as amended, classifies the mea suring instruments under Item  4.1.4 
in the annex entitled ‘List of specified measuring instruments’ as measuring instruments subject to type 
approval and mandatory verification.  
This legislation (Measure of a General Nature) will be notified in accordance with Directive (EU) 
2015/1535 of the European Parliament and of the Council of 9 September  2015 laying down a procedure 
for the provision of information in the field of technical regulations and of rules on Information Society 
services.  
III. 
I N S T R U C T I O N S  
In accordance with Section 172(l) APC in conjunction with Section 39(l) APC, the CMI has stipulated 
a time limit for comments of 30  days as of the date of posting the draft on the official notice board.  
Comments submitted after this time limit wi ll not be considered.  
The persons concerned are hereby invited to comment on this draft Measure of a General Nature.  With 
regard to the provisions of Section 172(4) APC, comments are to be submitted in writing. 
Pursuant to the provisions of Section 174(1) APC, in conjunction with the provisions of Section 37(1) 
APC, it must be clearly stated who is submitting the comments, which general measure the comments 
concern, how the draft contradicts legislation or how the general measure is inaccurate. The comments  
must also contain the signature of the person making the comments.  
The supporting documents for this draft general measure may be consulted at the Czech Metrology 
Institute, Legal Metrology Department, Okružní 31, 638 00 Brno, after making arrangements by  
telephone.  
This draft general measure shall be posted for 15  days.  
 
 
Czech Metrology Institute  
Director General