Decree of the Ministry of Industry and Trade No. 338 / 2000 Coll.
Decree of the Ministry of Industry and Trade laying down requirements for electrometers marked with EEC mark
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338
DECLARATION
Ministry of Industry and Trade
of 6 September 2000
laying down requirements for electrometers marked with EEC mark
The Ministry of Industry and Trade provides, pursuant to Section 27 of Act No. 505 / 1990 Coll., on Metrology, as amended by Act No. 119 / 2000 Coll., ("the Act ') for the implementation of Sections 6 (2) and 9 (1) of the Act:
This decree sets out requirements for new, directly connected inductive meters of electrical energy with one or more tariffs designed to measure active power of a single phase or multi-phase current with a frequency of 50 Hz and with a precision class of 2 (hereinafter referred to as "electrometers').
Electrometers may be marked with the EEC type-approval mark and the initial EEC verification mark, the graphic form of which is provided for in the specific legislation, (2) only if they comply with the requirements set out in the Annex to this Regulation and the fulfilment of which has been verified by the procedures laid down in the specific legislation.2)
This Regulation shall enter into force on the day of the publication of the sectoral annex to the Protocol to the Europe Agreement establishing an association between the Czech Republic, of the one part, and the European Communities and their Member States, of the other part, on conformity assessment and acceptance of industrial products in the Collection of International Treaties, or on the date of the entry into force of the Treaty of Accession of the Czech Republic to the European Union, if that date is earlier.
Minister:
Doc.
Annex to Decree No 338 / 2000 Coll.
ELECTROMETERS REQUIREMENTS
1. DEFINITION OF CERTAIN INJURY USED IN THIS ANNEX
1.1 Influencing variable or factor
Any variable or factor other than the measured variable whose effects may alter the measurement result.
1.2 Change in error as a consequence of variable
The difference between electrical meter errors when one influencing variable includes two consecutive specified values.
1.3. Reference value affecting variables
The value of this variable on the basis of which certain characteristics of the electrometer are determined.
1.4 Basic current (Ib)
The value of the current by which the critical properties of the electrometer are determined.
1.5 Nominal maximum current (Imax)
The maximum value of the current at which the electrometer must comply with the requirements of this Directive.
1.6 Non-linear distortion factor
The ratio of the effective value of the harmonics content, obtained by subtracting the basic component from the neinus alternating variable, to the effective value of the neinus variable. The non-linear distortion factor is usually expressed as a percentage.
1.7 Basic speed
Rated rotor rotation rate, expressed in revolutions per minute under the reference conditions of the electrometer, through which the basic current is passed at the unit power factor.
1.8 Basic torque
The nominal torque value of the disc at rest, the electrometer being in reference conditions and passing through the basic current at a power factor equal to one.
1.9 Type
The term used to define all electrical meters with one or more tariffs manufactured by the same manufacturer and characterised by:
- the same metrological characteristics;
- the uniformity of the design of the parts determining these characteristics;
- the same number of current winding amps for basic current and the same number of volt volts for reference voltage;
- the same ratio of the rated maximum current to the baseline current.
The type may include different basic currents and different values of the reference voltage.
Remarks
(a) These electrometers shall be marked by the manufacturer with one or more groups of letters or digits or a combination of letters and digits. The type shall have only one marking.
(b) The type shall be represented by three samples of the electrometer intended for EEC type-approval tests, the characteristics of which (basic current and reference voltage) shall be selected by the relevant metrological service from those specified in the tables proposed by the manufacturer (see paragraph 6.1.1).
c) Individual designs of one type may differ in the number of winding threads and in the value of the basic current from those parameters representing the type. To obtain the full number of turns, a product with the value closest to or less than the value shall be selected.
For this reason alone, the number of turns per volt of voltage winding may differ by no more than 20% from the winding of the sample of the electrometer representing the type.
d) The ratio of the highest rate of rotation to the lowest rate of rotation of the disc of each electrometer of the same type shall not exceed 1: 5.
2. REQUIREMENTS FOR MECHANICAL IMPLEMENTATION
2.1 General
Electrometers shall be designed and constructed in such a way as to avoid any hazard in normal use under normal conditions and in particular to ensure:
- safety of persons against electric shock;
- the safety of persons against the effects of excessive temperature;
- safety from spreading fire.
All parts which are subject to corrosive effects under normal working conditions shall be effectively protected. It must not be possible to damage or damage the atmosphere in normal handling conditions.
The electrometer shall have adequate mechanical strength and withstand an elevated temperature which may occur under normal working conditions.
The components shall be reliably fixed and secured against loss during transport or normal use.
The electrical connections shall be so designed as to avoid any interruption of the circuit, including any congestion conditions specified in this Decree.
The design of the electrometer shall be such as to reduce to a minimum the risk of short circuit through insulation between two live parts and accessible conductive parts due to release, winding, unscrew screws, etc.
2.2. Cover
The electrometer housing shall be almost dust-proof and shall be capable of being sealed in such a way that the inside parts of the electrometer are accessible only after the seal has been broken.
It shall not be possible to remove the cover without the use of a tool, coin or similar device.
The cover shall be so designed and arranged that any temporary deformation cannot prevent the corresponding operation of the electrometer.
Electro-meters designed to be connected to a network with a voltage against the ground of more than 250 V, which are covered with accessible metal parts, shall be equipped with a protective clamp.
For electrometers designed to be connected to a reference voltage network against the ground 250 In or less, which have a metallic or partly metal housing, appropriate measures shall be taken to connect the housing to the protective circuit.
2.3 Windows
If the cover of the electrometer is not transparent, then it shall be provided with one or more windows allowing the reading of the counter data and the tracking of the disc movement. This window shall be covered with transparent material plates which cannot be withdrawn without damage to the seal.
2.4. Clamp - clamp board
The clamps shall be grouped into one or more terminals with sufficient mechanical strength to enable fixed wires or cables to be connected.
It shall be possible to disconnect voltage terminals from the input current terminals without difficulty.
The connection of conductors to terminals shall be done in such a way as to ensure sufficient and permanent contact without risk of release or excessive warming. The openings in the insulating material which extend the clamp openings shall be large enough to allow easy insulation of the conductors.
Note
The material from which the block of clamps is made shall comply with the test set out in ISO Recommendation R 75 (1958), Part 6, for a temperature of 135 ° C.
2.5 Clamp cover
The clamps of the electrometer shall be covered with a housing that can be sealed independently of the electrometer housing. After the electrometer has been installed on the electrometer plate, the clamps shall not be accessible without breaking the seal of their housing. The clamp cover shall therefore cover the block of clamps, the screws which hold the wires in the terminals and, if necessary, the sufficient length of the connecting wires and their insulation.
2.6.
The counters can be cylindrical or hand type.
The unit of the counter is kilowatt hour [kWh].
For cylindrical counters, the units are marked near the cylinder assembly.
For hand-held counter types, scales (except for the minimum value scale) are marked in 10 equal sections and numbered from zero to nine. The unit scale shall be marked in 1d divided by 1 kWh and, in the vicinity of each other, the number of kWh corresponding to one piece of this scale shall be marked, i.e. 10, 100, 1 000, 10 000.
The scale of the hand-held counter or cylinder-type counter showing the tenth of the subtracted unit shall be coloured.
In addition, the scale or continuously rotating cylinder showing the lowest value shall contain a scale divided into 100 sections or shall have any other arrangement which provides a similar accuracy of reading.
The counter shall allow energy recording, from zero and for at least 1,500 hours, corresponding to the maximum current at reference voltage and unit power factor.
All data appearing on the counter shall be identifiable and easily readable.
2.7 Direction of turning the disc and its marking
The edge of the disc visible by the observer at the front of the electrometer shall move from left to right. The direction of rotation shall be visibly and indelibly marked with an arrow.
The edge or edge and the upper face of the disc shall be marked with a main mark between 1 / 20 and 1 / 30 of the disc circumference, which would facilitate the reading of the number of turns.
There may also be signs on the disc that allow stroboscopic or other tests to be carried out. These marks shall not prevent the use of the main mark when used for photometric reading of the number of disc speeds.
3. ELECTRICAL IMPLEMENTATION REQUIREMENTS
3.1. Loss
3.1.1 Voltage circuits
The losses in each voltage circuit at the reference voltage, the reference frequency and the reference temperature shall not exceed 2 W and 8 VA for single phase electrometers and 2 W and 10 VA for multi-phase electrometers.
3.1.2 Current circuits
For measuring instruments having a basic current of less than 30 A, the loss in any circuit at the base current, reference frequency and reference temperature shall not exceed 2,5 VA. For higher basic current losses shall not exceed 5 VA.
3.2. Heat
Under normal conditions of use, the winding and insulation shall not reach a temperature that could adversely affect the function of the electrometer.
When each current circuit is powered by its rated maximum current and each voltage circuit (and auxiliary circuits are powered for longer than their thermal time constant) is powered by 1.2 times the reference voltage, then warming (Δt) of different parts of the electrometer at an ambient temperature not exceeding 40 ° C shall not exceed the values given in the table below.
The electrometer shall be tested for two hours and shall not be exposed to draught or direct sunlight.
| Části elektroměru | Δt ve°C |
| Vinutí | 60 |
| Vnější povrch krytu | 25 |
The electrometer shall not show any damage after the test and shall comply with the AC test according to paragraph 3.3.3.
The winding temperature is determined by the resistance method (see IEC Publication 28 "International copper resistance standard ').
When measuring the resistance of the circuit, the supply to the electrometer shall be at least 100 cm long and shall have a cross-section such that the current density is less than 4 A / mm2. The measurement of the change of resistance shall be carried out on terminals.
3.3 Dielectric properties
The electrometer and its auxiliary equipment, if any, shall be such that they retain adequate dielectric properties under normal conditions of use, taking into account the atmospheric effects and the various stresses to which the circuits of the electrometers are exposed in normal use.
Therefore, the electrometer shall comply with the dielectric tests described in paragraphs 3.3.2 and 3.3.3 without damage.
The tests shall be carried out only on a complete new electrometer and with the housing installed (except in the cases below) and the clamping cap installed, screw the clamps as if they had fixed a wire with the maximum possible diameter.
These tests shall be performed only once on any electrometer and their procedure shall be in accordance with IEC Publication 60: "High Voltage Tests' (1962).
Note: If the arrangement of the electrometer terminals differs from that of the electrometer terminals that was originally approved, the dielectric performance tests shall be carried out for all different terminals.
For the purpose of these tests, the expression "ground 'shall have the following meaning:
(a) if the electrometer housing is made entirely of metal, the ground itself is a housing located on a flat conductive surface;
(b) if the housing of the electrometer or part thereof is made of insulating material, the ground is a conductive film connected to the conductive surface on which the electrometer is located.
Where the clamp cover allows, a gap of approximately 2 cm shall be left between the foil and the wire holes in the clamp housing.
During the impulse and alternating voltage tests, the untested voltage or current circuits shall be connected either to the skeleton or to the ground as specified below.
First, an impulse test and then an alternating voltage test shall be performed.
During these tests there shall be no skip, penetration or penetration.
After these tests there shall be no change in the percentage error of the electrometer greater than the measurement uncertainty.
In this section, the expression "all clamps' means the whole set of terminals of current circuits, voltage circuits, and, if any, auxiliary circuits having a reference voltage above 40 V.
3.3.1 General conditions for dielectric quality tests
These tests shall be carried out under normal conditions of use. During the test the insulation quality shall not be affected by dust or excessive moisture.
Unless otherwise specified, the normal conditions for insulation tests are:
- ambient temperature between 15 ° C and 25 ° C;
- relative humidity 45% to 75%;
- atmospheric pressure 86.103 to 106.103 Pa (860 mbar up to 1,060 mbar).
3.3.2. Pulse voltage test
The impulse test is designed to determine the ability of the electrometer to withstand without damaging short-term overvoltage of high values.
Note: The purpose of the tests according to paragraph 3.3.2.1 above is to ensure, on the one hand, the quality of the insulation of the voltage winding between the coils or between layers, as well as the quality of the insulation between different circuits of the electrometer which are connected in normal operation to different phases of the network between which overvoltage may occur.
The text referred to in paragraph 3.3.2.2 is intended to ensure an overall verification of the insulation behaviour of all electrical circuits of electrical meters against the ground. This insulation is a basic safety factor for persons in case of network overvoltage.
The generator energy used for this test shall comply with the relevant requirements of IEC Publication 60. The shape of the impulse wave is normalized 1,2 / 50 and its peak value is 6 kV. For each test, the impulse voltage is added ten times with the same polarity.
3.3.2.1. Insulation test of voltage circuits and insulation between circuits
The test shall be performed independently of any circuit (or assembly of circuits) which are isolated from other circuits by normal use of the electrometer. Clamp of circuits not tested by impulse voltage shall be connected to the ground.
If, in normal use, voltage and current circuits of the propulsion element are combined together, the test shall be carried out on the whole. The second end of the voltage circuit shall be connected to the ground and the impulse voltage shall be attached between the current circuit clamp and the ground.
If several voltage circuits of the electrometer have a common point, this point shall be connected to the ground and the impulse voltage shall be gradually added between each free end (or current circuit connected to it) and the ground.
The auxiliary circuits intended to be connected directly to the network, having a reference voltage exceeding 40 V, shall be subjected to an impulse voltage test under the same conditions as those for voltage circuits. Other auxiliary circuits shall not be tested.
3.3.2.2. Isolation of electrical circuits against the ground test
All terminals of circuits of electrical meters, excluding terminals of auxiliary circuits with a reference voltage not exceeding 40 V, shall be combined.
Auxiliary circuits with a reference voltage not exceeding 40 V shall be connected to the ground.
The impulse voltage shall be applied between all circuits of the electrometer and the ground.
3.3.3. AC voltage test
The alternating voltage test shall be carried out according to the table below.
The test voltage with a sufficiently sinusoidal 50 Hz frequency shall be applied for one minute. The power supply shall be capable of delivering at least 500 VA.
During tests A and B according to the table below, circuits not tested by voltage shall be connected to the skeleton.
During the ground tests (C in the table below), auxiliary circuits with a reference voltage not exceeding 40 V shall be connected to the ground.
| Zkušební napětí (efektivní hodnota) | Bod přiložení zkušebního napětí | ||
|---|---|---|---|
| A. | Zkoušky, které mohou být provedeny při odejmutém krytu elektroměru a krytu svorek. - mezi kostrou a: | ||
| 2 kV | (a) každou sestavou vinutí proud-napětí jednoho a téhož hnacího prvku, které jsou při normálním použití spojeny dohromady, ale jsou od ostatních obvodů odděleny a vhodně izolovány; | ||
| 2 kV | (b) každým pomocným obvodem nebo sadou pomocných obvodů, které mají společný bod, kde je referenční napětí větší než 40 V; | ||
| 500 V | (c) každým pomocným obvodem, který má referenční napětí menší než 40 V. | ||
| 600 V nebo dvojnásobek | B. | Zkouška, která může být provedena bez krytu svorek, ale s nasazeným krytem, pokud je kovový - mezi proudovým obvodem a napěťovým obvodem každého hnacího prvku, které jsou normálně spojeny dohromady, přičemž toto spojení se během zkoušky přechodně přeruší (*) | |
| napětí přikládaného k napěťovému vinutí za referenčních podmínek, kde je referenční napětí větší než 300 V (platí vyšší hodnota) | |||
| 2 kV | C. | Zkouška se provede s uzavřeným pouzdrem, kryt elektroměru a kryt svorek je upevněn - mezi všemi proudovými a napěťovými obvody a rovněž mezi pomocnými obvody, jejichž referenční napětí je větší než 40 V, spojenými dohromady a zemí elektroměru. | |
| (*) Přesně řečeno, toto není zkouška dielektrické pevnosti, ale prostředek pro ověření, zda izolační vzdálenosti jsou při rozpojeném připojovacím zařízení dostatečné. | |||
4. DATA TO BE INCLUDED ON ELECTROMETERS
4.1 Label with rated values
Each electrometer shall bear a label which may be either a plate of the counter or a label fixed inside the electrometer.
The label or plate of the counter shall bear the following particulars visible from the outside in indelible and legible form:
(a) the manufacturer's identification mark or trade mark;
(b) the type designation;
(c) a mark certifying EEC type-approval of the electrometer;
(d) a description of the number and arrangement of driving elements, either in the form of: single-phase-two conductors, three-phase-four conductors, etc., or by the use of signs of conformity with a Czech technical standard transposing a European standard or a foreign standard transposing a European standard;
(e) reference voltage;
(f) basic current and rated maximum current, marked as: 10 - 40 A or 10 (40) A;
(g) 50 Hz reference frequency;
(h) the electrometer constant in one of the following inscription shapes: x Wh / ot, or x ot / kWh;
(i) the production number of the electrometer and the year of its manufacture;
(j) reference temperature, if different from 23 ° C.
Information such as the manufacturer's location, business description, special production number, name of the electricity supplier, brand of compliance with the European standard and identification number of the wiring scheme may also be on the electrometer. Any other information or inscriptions shall be prohibited unless specifically approved.
4.2 Schematic of connection and marking of terminals
Each electrometer shall be marked with an understandable wiring diagram showing the connection between the connecting terminals, including the terminals of the auxiliary devices and conductors to be connected. For three-phase electrometers, the sequence of phases for which the electrometer is designed shall be indicated. The wiring diagram may have an identification number marked on the label with rated values. If the terminals of the electrometer are marked, this marking shall be indicated in the diagram. The schematic of the wiring may be replaced by an identification number as defined in the technical standard of the State in which the electrometer will be used.
5. METHOLOGICAL REQUIREMENTS
5.1 Maximum permissible errors
Under the reference conditions described in point 5.2, errors of single-phase and multi-phase electrometers with symmetrical loads shall not exceed those of Table I and multi-phase electrometers with single-phase loads (at symmetrical voltages) shall not exceed those of Table II.
Table I
| Hodnota proudu | Účiník | Maximální dovolená chyba |
|---|---|---|
| 0,05 Ib | 1 | 2,5 % |
| 0,1 Ib < I < Imax | 1 | 2,0 % |
| 0,1 Ib | 0,5 indukt. | 2,5 % |
| 0,2 Ib < I < Imax | 0,5 indukt. | 2,0 % |
Table II
| Hodnota proudu | Účiník | Maximální dovolená chyba |
|---|---|---|
| 0,2 Ib < I < Ib | 1 | 3,0 % |
| Ib < I < Imax | 1 | 4,0 % |
| Ib | 0,5 indukt. | 3,0 % |
In the case of a baseline current and a unit power factor, the difference between a single phase load electrical meter error and a percentage of a symmetrical multiphase load error shall not exceed 2,5%.
Note: A single phase load of a multi-phase electrometer means that the load is connected to the voltage between one phase and the middle wire of the four-wire system (one of which is central or to the voltage between two phases of the three-wire system (without the middle wire). In any case, a complete voltage system shall remain on the electrometer.
5.2. Reference conditions
In addition to the exceptions specifically set out in this Annex, tests shall be carried out to determine errors and error changes as a function of variable influence under the following reference conditions:
(a) the electrometer must be closed, i.e. the cover of the electrometer is in its position;
(b) in the case of a cylindrical counter, only the fastest rotating cylinder is in operation;
(c) before any measurement, the voltage shall be connected for at least one hour and each test current shall be adjusted by a gradual increase or decrease and shall be connected long enough to stabilise the rotation rate of the disc;
In addition, for multi-phase electrometers:
(d) the sequence of phases shall correspond to a direct sequence (as shown in the wiring diagram);
(e) voltage and currents shall be symmetrical for practical purposes, i.e.:
- each current in the conductors must not differ by more than 2% from the mean value of these currents;
- phase displacement between these currents at the corresponding phase voltage against the central conductor shall not differ by more than 2 ° at any power factor.
The reference values affecting quantities are given in Table III.
TABLE III
| Ovlivňující veličiny | Referenční hodnota | Tolerance |
|---|---|---|
| Teplota okolí | Referenční teplota, nebo pokud není uvedena, 23 °C | ± 2°C |
| Poloha při použití | Vertikální poloha při použití (1) | ± 0,5 ° |
| Napětí | Referenční napětí | ± 1 % |
| Kmitočet | Referenční kmitočet 50 Hz | ± 0,5 % |
| Tvar vlny | Napětí a proudy sinusového průběhu | Činitel nelineárního zkreslení menší než 3 % |
| Magnetická indukce vnějšího původu při 50 Hz | Magnetická indukce rovna nule | Hodnota indukce, která nezpůsobí změnu relativní chyby o více než 0,3 %(2) |
| 1) Zajištění vertikální polohy při použití Elektroměr musí být konstruován a sestaven tak, aby bylo zajištěno jeho upevnění ve správné vertikální poloze (v obou kolmých rovinách, tj. vertikální a horizontální), když: a) základna elektroměru je kolmo ke svislému povrchu a b) průvodní značka (např. spodní hrana svorkovnice) nebo průvodní značka na krytu elektroměru je horizontální | ||
| 2) Zkušební postup pro toto ověření sestává: a) u jednorázového elektroměru z určení chyb nejprve s elektroměrem připojeným k síti běžným způsobem, potom s reverzovanými zapojeními proudového a napěťového obvodu. Polovina rozdílu mezi těmito dvěma chybami je velikost změny chyby. Jelikož je vnější pole fáze neznámé, provede se ověření při 0,1 Ib s jednotkovým účiníkem a při 0,2 Ib s účiníkem 0,5; b) u vícefázového elektroměru z provedení tří měření při 0,1 Ib s jednotkovým účiníkem; po každém měření je zapojení proudových a napěťových obvodů posunuto o 120° (elektrických) beze změny sledu fází. Maximální rozdíl mezi takto změřenými chybami a jejich aritmetickým průměrem je velikost změny chyby. | ||
5.3 Effects on variables
The change in error shall be determined for each influencing variable under the conditions set out in Table IV. All other conditions referred to in point 5.2 shall be observed.
TABLE IV
| Ovlivňující veličina | Způsob zkoušky a podmínky | Účiník | Max. hodnota průměrné teploty, koeficient (±) |
|---|---|---|---|
| Teplota(1) | Od 0,1 Ib do Imax | 1 | 0,1 % °K |
| Od 0,2 Ib do Imax | 0,5 indukt. | 0,15 % °K | |
| (1) Pro teplotu stanovenou mezi 10 °C a 30 °C je hodnota koeficientu průměrné teploty určena v rozsahu 20 °C se středem na stanovené teplotě. | |||
| Ovlivňující veličina | Způsob zkoušky a podmínky | Účiník | Max. hodnota průměrné teploty, koeficient (±) |
|---|---|---|---|
| Změna maximální dovolené chyby (±) | |||
| Poloha | Pro odklon od vertikály o 3° v libovolném směru: | ||
| 0,05 Ib | 1 | 3,0 % | |
| Ib 2. Imax | 1 | 0,5 % | |
| Napětí | Pro změnu 10 % v jakémkoli směru od referenčního napětí: | ||
| 0,1 Ib | 1 | 1,5 % | |
| 0,5 Imax | 1 | 1,0 % | |
| 0,5 Imax | 0,5 indukt. | 1,5 % | |
| Kmitočet | Pro změnu 5 % v jakémkoli směru proti 50 Hz: | ||
| 01 Ib | 1 | 1,5 % | |
| 0,5 Imax | 1 | 1,3 % | |
| 0,5 Imax | 0.5 indukt. | 1,5 % | |
| Tvar vlny (1) | Pro zvětšení třetí harmonické proudové vlny o 10 %: | ||
| při Ib | 1 | 0,8 % | |
| Magnetická indukce vnějšího původu (2) | Pro magnetickou indukci 0,5 mT při referenčním kmitočtu za nejméně příznivých podmínek fáze a směru: | ||
| při Ib | 1 | 3,0 % | |
| Obrácený sled fází | Pro obrácené pořadí sledu fází: | ||
| 0,5 Ib až Imax (symetrická zátěž) | 1 | 1,5 % | |
| 0,5 Ib jednofázová zátěž | 1 | 2,0 % | |
| Magnetické pole příslušenství | 0,05 Ib | 1 | 1,0 % |
| Mechanická zátěž počítadla nebo každého počítadla vícetarifového elektroměru (3) | 0,05 Ib | 1 | 2,0 % |
| (1) Při určování změny chyby jako funkce tvaru vlny musí harmonický obsah v křivce průběhu napětí zůstat menší než 1 % a fáze třetí harmonické obsažené v křivce průběhu proudu se musí měnit od nuly do 360°. (2) Požadovaná indukce se získá ve středu kruhové cívky o středním průměru 1 m, čtvercového průřezu, s malou radiální tloušťkou v poměru k průměru cívky, která poskytuje magnetomotorickou sílu odpovídající 400 ampérzávitům. (3) Vliv mechanického zatížení počítadlem se musí při justování elektroměru kompenzovat. | |||
5.4 Effects of short-term current overload
The test circuit shall be non-inductive. After short-term current overload and maintenance of voltage at voltage terminals (about 1 hour), the electrometer shall return to its initial temperature.
Electrometers shall be able to withstand a current rate (e.g. from a discharge capacitor or from a mains by means of a thyristor control) with a peak value equal to 50 times the rated maximum current (up to 7,000 A) and a total of 1 ms the current value greater than 25 times the rated maximum current (or 3,500 A).
At the end of this test the change in error shall not exceed 1,5 per cent at the base current and unit power factor.
5.5 Change of error caused by self-heating
After the reference voltage has been maintained for at least one hour without passing through the current, the current winding shall be loaded with the rated maximum current. The electrometer error shall be measured immediately after its entry into service and then at sufficiently short intervals allowing the correct recording of the error curve as a function of time.
The test shall take place for at least one hour and in any case until the recorded error change for 20 minutes has changed by more than 0,2%.
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Regulation Information
| Citation | Decree of the Ministry of Industry and Trade No. 338 / 2000 Coll., laying down requirements for electrometers marked with EEC mark |
|---|---|
| Regulation Type | Order |
| Author | - |
| Collection | Code of Laws |
| Date of Promulgation | 26.09.2000 |
|---|---|
| Effective from | 21.04.2004 |
| Effective until | - |
| Status | Valid |
The regulation text is for informational purposes only.
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