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KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.

KPB INTRA s.r.o. How to order (demand) transformers correctly. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com. How to order (demand) a transformer correctly. Transformer type selection.

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KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.

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  1. KPB INTRA s.r.o. How to order (demand) transformers correctly KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  2. How to order (demand) a transformer correctly • Transformer type selection Measuring voltage or current transformer VTS 12 CTS 12 Indoor or outdoor environment CTS 25 CTSO 38 KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  3. How to order (demand) a transformer correctly Types of current transformers • CTS 25 • Supporting type • CTB 25 • Bushing type • CTB 25 • Pass type KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  4. How to order (demand) a transformer correctly Types of voltage transformers • VTS 25 • Supporting type • Earthed measuring phase – earth • E.g. 22000/√3//100/√3/100/3 V • VTD 25 • Supporting type • Unearthed measuring between phases • E.g. 22000//100 V KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  5. How to order (demand) a transformer correctly • VTS 25 • Supporting type of • earthed voltage transformer • with fuse • VTD 25 • Supporting type of • unearthed voltage transformer • with fuse KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  6. How to order (demand) a transformer correctly Functions and types of fuses • A fuse is used to protect adjacent equipment in case of transformer destruction • An appropriate type of fuse corresponds to each type of transformer KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  7. How to order (demand) a transformer correctly • Technical parameters of measuring transformers Measuring current transformer 2.a.1 Insulation levels • Insulation voltage/Testing voltage/Testing impact voltage • e.g. 25/50/125 kV • 36/70/170 kV  acc. to IEC 60044-1 • 38.5/80/180 kV acc. to ČSN • 40.5/95/200 kV acc. to GOST Rated frequency 50 (60Hz) KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  8. How to order (demand) a transformer correctly 2.a.2 Rated conversion and number of secondary windings • E.g. 100//5 A or 250//1/1 A • If switch-over type is required, the primary current is to be stated in conversion in the form of • e.g. 100-200//5 A (one branch) or 50-100-200//5 A (two branches) • Rated conversion consists of rated • Primary current     • Secondary current • Note: • It is appropriate to separate the primary current from the secondary one with a double slash // in the notation in • order to increase clarity. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  9. How to order (demand) a transformer correctly 2.a.2.a Primary current Selection from series in accordance with standards 10,12.5,15,20,25,30,40,50,60,75A An atypical current, e.g. 65 A or 630 or 515 A should be consulted with the designer. 2.a.2.b Secondary current Only 5 A or 1 A (or 2 A) is acceptable according to standards Other values, e.g. 2.5 A should be consulted with the designer (accuracy may not always be guaranteed as we do not have the necessary measuring equipment) KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  10. How to order (demand) a transformer correctly Number of secondary windings - Is given by the values after a double slash in conversion Examples 400//5 A One secondary winding 5A 150//5/1 A Two secondary windings, first winding - 5 A , second winding 1 A 700//1/1/1 A Three secondary windings (all 1A) 150-300//5//5 A Two secondary windings (both 5A) with one branch on secondary winding   Number of windings may be 1 , 2 , 3 or exceptionally 4 KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  11. How to order (demand) a transformer correctly Basic diagrams of winding of measuring current transformer Single core type Three-core type Two-core type KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  12. How to order (demand) a transformer correctly Basic diagrams of winding of measuring current transformer Single core type with one branch Three-core type with one branch on each core Two-core type with one branch on each core KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  13. How to order (demand) a transformer correctly The following parameters should be given for individual windings: • Rated load (burden) in VA • E.g.15 VA • II.a) Accuracy class for measuring windings • 0.2 ( 0.2S) • 0.5 (0.5S) • II.b) Accuracy class for protection winding 5P or 10P • 5P corresponds to 1 % error at rated current passing • 10P corresponds to 3 % error at rated current passing KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  14. How to order (demand) a transformer correctly III.a) Instrument security factor FS for measuring windings It is stated as FS , e.g. FS5 or FS10 It expresses the ratio of resulting exciting current with respect to rated current at which the transformer’smagnetic circuit will be oversaturated This parameter is important for protection of measuring instruments on the transformer’s secondary side The real instrument security factor for measuring instruments is always lower than the value stated in the label, e.g. for FS5, the max. factor is 4.999 In the case of passing a primary current higher than a quintuple of the primary current, a current lower than 25 A will appear in the secondary circuit at conversion to 5A (quintuple of 5A) Or, in the case of conversion to 1 A, a current lower than 5 A will appear in the secondary circuit (quintuple of 1A) KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  15. How to order (demand) a transformer correctly Example KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  16. How to order (demand) a transformer correctly III.b) Instrument security factor for protection windings • Accuracy limit factor: • Ratio of rated primary overcurrent at a given precision and rated primary current • Follows always after accuracy class • E.g. 5P10 or 10P20 (instrument security factor is either 10 or 20) • Real instrument security factor of protection windings is always higher than the stated value. • It must be guaranteed for transformer winding that measuring error will not exceed 10 % in the case of passing overcurrent in the value of a multiple of instrument security factor 10% • It is important for correct operation of protections • There is a risk of protection failure if it has been set incorrectly (higher instrument security factor than that stated on the label (transformer will be oversaturated before protection activation) KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  17. How to order (demand) a transformer correctly Example: Transformer 50//5 A Accuracy class in combination with instrument security factor 10P10 The transformer will measure with max 10% error if a current of 500 A is passing, i.e. measured current will be at least 450 A Instrument security factor 10 guarantees correct functioning of protection winding up to tenfold the rated current. However, rated load in VA may not be exceeded as this could affect the instrument security factor. • E.g. If the above-mentioned burden is 10 VA and instrument protection factor 10, the instrument security number will be reduced to 7 upon winding loading with a burden with output of 15 VA • Load (burden) may be increased by too long a supply line (several tens of meters) between the protection and terminal board or by too small a cross section of wires, which is why this fact should be considered when dimensioning rated burden of protection winding. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  18. How to order (demand) a transformer correctly 2.3 Short-circuit currents 2.3.a) Rated short-time thermal current Ith - rated short-time thermal current: effective value of primary current that the transformer withstands for 1 second with secondary winding short circuit without damage to the transformer. Also times other than 1 second such as 0.5 s, 2 s, 3s may be agreed upon. 2.3.b) Rated dynamic current Idyn- rated dynamic current: peak value of primary current which the transformer withstands without electric or mechanical damage caused by electrodynamic force in the case of secondary winding short-circuit. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  19. How to order (demand) a transformer correctly • Rated dynamic current (1s) corresponds to a 2.5 multiple of short-term thermal current Ith short-circuit duration 1s. Short-circuit conditions in the mains will be specified by the specialized designer. • If a different short-circuit duration time than one second is stated, it is necessary to state this fact in a request or an order! Idyn= 2.5 x Ith • These short-circuit currents should be written in a request as follows: Ith/Idyn kA, the value is to stated in kA, e.g. 16/40 kA. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  20. How to order (demand) a transformer correctly Data which should be included in a request (summary) • Current transformer type • Conversion • Insulation levels • Rated frequency • Parameters of individual windings – burden/accuracy class/instrument security factor • Short-circuit currents Ith/Idyn • Official verification (calibration) – if requested • Non-standard modifications • E.g. tropical design, PR super-structures, different base boards, etc. • Such data must be specified for each winding separately as specification should be • unambiguous and complete in order to allow offering of precisely the required type • of the instrument transformer KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  21. How to order (demand) a transformer correctly Example of incorrectly specified demand Frequently the customer describes an instrument with the following parameters: CTS 25 100//5/5 15 VA 0.5 FS5 It is apparent from conversion that it is a two-winding current transformer; however, parameters of the other winding are not specified and we can only estimate that the other winding is the same as the first one. If the same windings are concerned, it is advisable, because of the unambiguous character of the specification, to statethe type as follows: CTS 25 100//5/5 15 VA 0.5 FS5 15 VA 0.5 FS5 Please always state complete data in order to prevent any misunderstanding! An example of a correctly specified demand CTS 25 300//5/5/5 A 25/50/125 kV 50 Hz 25/63 kA 15 VA 0.2 FS5 10 VA 0.5 FS10 15 VA 5P10 Official verification for the first winding KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  22. How to order (demand) a transformer correctly • Technical parameters of measuring parameters Measuring voltage transformer 2.b.1 Insulation levels • Insulation voltage/Testing voltage/Testing impact voltage • E.g. 25/50/125 kV • 36/70/170 kV  acc. to IEC 60044-1 • 38.5/80/180 kV acc. to. ČSN • 40.5/95/200 kV acc. to GOST Rated frequency 50 (60Hz) KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  23. How to order (demand) a transformer correctly 2.b.2 Rated conversion and number of secondary windings • E.g. VTS 25 - 10000/√3//100/√3/100/3 V or VTD 25 - 22000//100 V • Instead of √3, it is possible to write V3 (VTS 25 22000/V3//100/V3 • Note: • It is appropriate to separate the primary current from the secondary one by a double slash // • in the notation in order to increase clarity. 2.b.2.a Standardized levels of primary voltages Standard voltage levels in the Czech Republic Earthed type: 11000/√3 V, 22000/√3 V, 35000/√3 V Unearthed type: 11000 V, 22000 V, 35000 V 2.b.2.b Standardized values of secondary voltages (measuring zone) Standard voltage levels in the Czech Republic Earthed type – measuring and protection winding: 100/√3 V, 110/√3 V Unearthed type – auxiliary winding: 100/3 V, 110/3 V Note: In the case that an unearthed transformer is used as a supply of low output of low voltage, it is also possible to select different secondary voltages, e.g. 220 V, 231 V, 380 V, 400 V, 500 V, etc. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  24. How to order (demand) a transformer correctly Number of secondary windings - is given by values after the double slash in conversion Examples 22000/√3//100/√3 V one secondary winding 100/√3 V 11000/√3//100/√3/100/3 V two secondary windings -the 1st measuring winding 100/√3 V -the 2nd auxiliary winding 100/3 V 35000/√3//100/√3/100/√3/100/3 V three secondary windings -the 1st measuring winding 100/√3 V -the 2nd measuring winding 100/√3 V -the 3rd auxiliary winding 100/3 V  Number of windings may be 1 , 2 , 3 or exceptionally 4 KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  25. How to order (demand) a transformer correctly Parameters for individual windings Each winding should include data as follows: • Burden size in VA • Accuracy class 0.2, 0.5, 1, 3P, 6P Accuracy classes for measuring windings are: 0.2,0.5,1 Accuracy classes for protection transformers: 3P and 6P Accuracy class for auxiliary windings: 6P If a measuring transformer contains more measuring windings, it is necessary to take into account the fact that individual windings affect each other so that a sum of their output may reach a maximum of the output of the transformer with one winding KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  26. How to order (demand) a transformer correctly Example Transformer VTS 25 output with one measuring secondary winding can reach an output of 30 VA in accuracy class 0.2 • The same transformer VTS 25 with two measuring windings reaches only max. output • 1st winding 15 VA in class 0.2 • 2nd winding 10 VA in class 0.2 • The same transformer VTS 25 with three measuring windings reaches only max. output • 1st winding 5 VA in class 0.2 • 2nd winding 5 VA in class 0.2 • 3rd winding 5 VA in class 0.2 Note: For spatial reasons, it is usually impossible to reach the maximum limit for a given accuracy class by the sum of individual windings, e.g. 15 VA + 10 VA < 30 VA Please consider whether it is necessary to require high outputs, e.g. 50VA in class 0.2 or 30 VA and 30VA in class 0.2 for a two-winding measuring voltage transformer. These requirements increase demands for instrument design and the transformer is less resistant to the phenomenon called ferro-resonance. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  27. How to order (demand) a transformer correctly Data which should be included in a demand (summary) Correctly specified demand: VTS 25 22000/V3//100/V3/100/3 V 25/50/125 kV 50 Hz 30 VA 0.5 50 VA 6P Official verification not required • Voltage transformer type • Conversion • Insulation levels • Rated frequency • Parameters of individual windings – burden/accuracy class • Official verification (calibration) if required • Non-standard modifications E.g. Tropical modification, PR superstructures, different base boards, etc. Such data must be specified for each winding separately as specification should be unambiguous and complete in order to allow offering of precisely the required type of the instrument transformer. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  28. How to order (demand) a transformer correctly Ferro-resonance The phenomenon called “ferro-resonance” appears in electric networks. Causes of its occurrence: • Presence of capacitors (cable supply lines, capacitor batteries, etc.) • Effect of inductivity of chokes and the transformer’s own inductivity • Occurrence of oversaturation and impacts at transient phenomena • Oscillation of electric power between instrument capacitances and inductivity Consequences: • Disturbing insulation of measuring voltage transformers • Progressive instrument destruction • In some cases, even sudden explosion of the instrument Note: This phenomenon will appear more frequently in future as a consequence of replacement of existing analog voltmeters with electronic ones because electronic voltmeters have a lower burden and thus also lower damping effects, which means that the existing transformers are less resistant with respect to this phenomenon. KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  29. How to order (demand) a transformer correctly Potential solution of the problem called ferro-resonance • Increase of primary winding resistance • Inconvenient as it increases instrument dimensions • It increases production costs substantially • It increases product price • Undersaturation of magnetic circuit 0.4T • It protects transformer against oversaturation • It is necessary in some cases, e.g. for railway applications • It increases instrument dimensions and product costs • It limits some existing parameters of the instrument, e.g. output • Use of resistor connected in open triangle with auxiliary windings MTN • (68 Ohm/ 200W (TR305 manufacturer: Tesla Blatná) • It reduces ferro-resonance effects • Low costs with respect to instrument purchase price Note: In the case that resistor connection would result in non-activation of parallel protection or signalling relay, it is possible to reduce consumption by connecting two resistors in series. connection diagram KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

  30. How to order (demand) a transformer correctly Thank you for your attention. Should you have any questions please feel free to contact: • Ing. Robert Knápek - Executive: +420 603 481 128 knapek@kpbintra.cz • Ing. Petr Novák – Business Department Manager: +420 604 237 033 novak@kpbintra.cz • Ing. Josef Stejskal – Technical Department Manager: +420 603 862 464 stejskal@kpbintra.cz www.kpbintra.com KPB INTRA s.r.o. , Ždánská 477, CZ-68501 Bučovice, tel.: +420 517 380 388, fax: +420 517 381 433, info@kpbintra.cz, www.kpbintra.com

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