ESSENTIAL CHANGES IN THE PRODUCT STANDARD IEC FOR LOW VOLTAGE MCC AND SWITCHGEAR

Transcription

1 ESSENTIAL CHANGES IN THE PRODUCT STANDARD IEC FOR LOW VOLTAGE MCC AND SWITCHGEAR Presentor: Roel Ritsma Entheq Technology Group Bas Bouman - Eaton Electric. André Muileboom - ExxonMobil Chemical Holland

2 The scope of the standard Low-voltage switchgear and controlgear assembly Combination of one or more low-voltage switching devices together with associated control, measuring, signalling, protective, regulating equipment, with all the internal electrical and mechanical interconnections and structural parts Slide 2 / Author /

3 IEC 439-series restructuring process In 1998 UK proposed a restructuring of the 439-series. Aim: To bring the structure of the 439-series in line with the general accepted format; To abandon the definitions TTA and PTTA and define clear(er) methods of verification After 10 years of work and 3 voting cycles the new IEC part 1 and 2 were issued January IEC-version issued, EN-version still pending. Slide 3 / Author /

4 New general accepted format IEC series: LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES Part 1: General rules Specific assemblies: Part 2: Power switchgear and controlgear Part 3: Distribution boards: (verified by test) Part 4: Building sites Part 5: CDC ad SCBD (power distribution) Part 6: Busbar trunking systems Part 3, 4, 5, 6 estimated to be ready for publishing in Slide 4 / Author /

5 Terms TTA and PTTA have been abandoned Because for PTTA more and more assemblies in the market did not comply with the standard. compliance by lip rather than by fact There are hardly any rules in IEC for PTTA to verify compliance. For petrochemical industries, PTTA has limited acceptance as design verification Slide 5 / Author /

6 Definitions TTA and PTTA Type Tested Assembly (TTA) A low-voltage switchgear and controlgear assembly which has been fully type tested (no deviations likely to significantly influence the performance are allowed) Partially Type Tested Assembly (PTTA) A low-voltage switchgear and controlgear assembly, containing both type-tested and non-type-tested arrangements. Non-type tested arrangements are derived (e.g. by calculation) from typetested arrangements. Slide 6 / Author /

7 Verifications TTA and PTTA have been replaced by different ways of verifications Verifications can be: Test Calculation Measurement (e.g. distances) Design rules Slide 7 / Author /

8 Verifications Testing IEC Verifications IEC Temperature rise limits 1 Temperature rise limits 2 Dielectric properties 2 Dielectric properties 3 Short circuit withstand strength 3 Short circuit withstand strength 4 Effectiveness of the protective circuit 4 Effectiveness of the protective circuit 5 Clearances and creepage distances 5 Clearances and creepage distances 6 Mechanical operation 6 Mechanical operation 7 Degree of protection (IP) 7 Degree of protection (IP) 8 EMC 8 EMC 9 Resistance of insulating materials to abnormal heat and fire 9 Resistance of insulating materials to abnormal heat and fire New items (next slide) Slide 8 / Author /

9 New verifications items Most of the verifications of material strength are copied from existing standards (f.e ) Mechanical strength, mechanical impact Corrosion Thermal stability, heat, UV-radiation Lifting Terminals for external conductors Slide 9 / Author /

10 Verifications of temperature rise Verification by analyses No Verification by test Option 1 (max 630 A) No Option 2 (max 1600 A) No Yes Yes Test requirement covered by tests on a similar arrangement No Yes Temperature rise test Assembly verified Slide 10 / Author /

11 Options: main criteria P C I C E u r o p e The maximum dissipation inside an assembly is defined by the manufacturer of the enclosure (max 630 A) or calculated according IEC (max 1600 A); The Watt-losses of all devices incorperated in the assembly are known from the manufacturer; No devices incorperated in the assembly shall be loaded in excess of 80% of the rated conventional free air thermal current; All conductors shall have a minimum cross-sectional area based on the current rating of the functional unit according to IEC 60364; Slide 11 / Author /

12 Temperature rise type test of devices (IEC 60947) Test in free air L L Excellent cooling by convection and thermal radiation Test conductors act as heat sinks (heat conduction ) Test conductors: Cross section given and at least 1 m long Slide 12 / Author /

13 Temperature rise test functional units (IEC 60439) Test inside assembly enclosure: Usually more than one device Short internal conductors Internal conductors sometimes thinner than for test of devices Cooling substantial worse than during type test of the devices Slide 13 / Author /

14 Options: main criteria P C I C E u r o p e The maximum dissipation inside an assembly is defined by the manufacturer of the enclosure (max 630 A) or calculated according IEC (max 1600 A); The Watt-losses of all devices incorperated in the assembly are known from the manufacturer; No devices incorperated in the assembly shall be loaded in excess of 80% of the rated conventional free air thermal current; All conductors shall have a minimum cross-sectional area based on the current rating of the functional unit according to IEC 60364; Slide 14 / Author /

15 Cross sections internal wiring Annex H of IEC Slide 15 / Author /

16 Temperature rise: verification The assembly is verified if the calculated air temperature at the mounting height of any device does not exceed the permissible ambient air temperature as declared by the device manufacturer.. Slide 16 / Author /

17 Verification of short circuit withstand strength Is het kortsluitvermogen < 10kA of de kapstroom < 17kA piek Ja Nee Nee Verificatie door analyse Ja Nee Referentie ontwerp aanwezig Ja Alle punten checklist met ja beantwoord Ja Nee Verificatie door vergelijking (berekening IEC/TR 61117) met een referentie ontwerp Nee Punten 6,8,9,10 checklist met ja beantwoord Kortsluitvastheid testen Ja Verdeelsysteem is geverifieerd Slide 17 / Author /

18 Comparison with tested reference design One of the 13 criteria: 6 Are the short-circuit protective devices of each circuit of the ASSEMBLY to be assessed equivalent, that is of the same make and series a) with the same or better limitation characteristics (I 2 t, I pk ) based on the device manufacturer s data, and with the same arrangement as the reference design? Yes No Slide 18 / Author /

19 Circuit breaker: correct SC behaviour Slide 19 / Author /

20 Circuit breaker: incorrect SC behaviour Slide 20 / Author /

21 Circuit breaker: risk of internal arc Supply side Direction pressure relief ciruit breaker Probability of dielectric breakdown Internal arc! Slide 21 / Author /

22 Internal arc Failure resulting in an internal arc Slide 22 / Author /

23 Specification by the User Actual In part 1 Annex C contains a table with the items that are subject to agreement between manufacturer and user.! Note: Method of testing is not an option in the table. Future The IEC committee is also working on a specifiers guide for the end user. This guide is to provide: A complete list to specify a LV assembly Guidance to individual items that need specified General explanation to certain topics Slide 23 / Author /

24 Specification internal arcing not included Requirements regarding internal arcing Assemblies that are regarded as critical and require a high level of safety requirements for withstanding the effects of internal arcing according to IEC should be specified. 7 criterions in 2 groups: a. Personal protection (criterions 1-5 to prove that the person in the vicinity of the assembly is not injured due to an event of internal arcing) b. Assembly protection (criterion 6 to prove that no propagation is established and criterion 7 to prove further operation of the assembly is possible) Slide 24 / Author /

25 Conclusions new IEC IEC (and its future specifiers and users guide), will give user and manufacturer an equal base of understanding and it will ease the product comparison of the various manufacturers; 2. Verifications according to the new standard are more extensive and rigid than under the former standard; 3. Criterions for deciding when to turn to IEC series with regards to requirements for construction and verification of an MCC can now be derived from the new standard. 4. Arc protection is still kept out of the standard and will have to be addressed separately by the user or specifier; Slide 25 / Author /

26 New standard IEC Thank you for listening! Questions? Slide 26 / Author /