Low voltage products in high altitudes

Transcription

1 WHITE PAPER Low voltage products in high altitudes Information and technical guidance for applications above 2000 m sea level This white paper provides information including technical guidance for high altitude applications of the following devices: Contactors associated with overload and/or short-circuit protective devices Starters associated with separate short-circuit protective devices Circuit-breakers and fuse-combination units used as short-circuit protective devices They are covered under the requirements of the IEC60947 series which gives limitations related to the insulation coordination of the devices and their performance. References The following documents are referred to for the applications in this white paper: IEC Guide111{ed2.0} IEC {ed3.0} IEC {ed5.1}b IEC {ed2.0}b Surge & lightning protection solutions (1TXH000375C0202)

2 White Paper Low voltage products in high altitudes 2 Definitions Clearance shortest distance in the air between two conductive parts Creepage distance shortest distance along the surface of a solid insulating material between two conductive parts Electrical breakdown failure of insulation under electric stress when the discharge completely bridges the insulation, thus reducing the voltage between the electrodes almost to zero Overvoltage any voltage having a peak value exceeding the corresponding peak value of maximum steadystate voltage at normal operating conditions R.m.s. withstand voltage highest r.m.s. value of a voltage which does not cause breakdown of insulation under specified conditions Rated impulse voltage impulse withstand voltage value assigned by the manufacturer to the equipment or to a part of it, characterizing the specified withstand capability of its insulation against transient overvoltages Rated insulation voltage r.m.s. withstand voltage value assigned by the manufacturer to the equipment or to a part of it, characterizing the specified (long-term) withstand capability of its insulation The significant parameters or items for the consideration of high altitude applications for these industrial products are as follows: Rated operational voltage (U e) A rated operational voltage of an equipment is a value of voltage which, combined with a rated operational current, determines the application of the equipment Rated insulation voltage (U i) The rated insulation voltage of an equipment is the value of voltage to which dielectric tests and creepage distances are referred Rated impulse withstand voltage (U imp) The peak value of an impulse voltage of prescribed form and polarity which the equipment is capable of withstanding without failure under specified conditions of test and to which the values of the clearances are referred Rated operational current (I e) A rated operational current of an equipment is stated by the manufacturer and takes into account the rated operational voltage, the rated frequency and the utilization category Overvoltage category conventional number based on limiting (or controlling) the values of prospective transient overvoltages occurring in a circuit Type of voltage system Installation altitude

3 White Paper Low voltage products in high altitudes 3 Important environmental parameters are: air pressure temperature pollution relative humidity condensation Essential for high altitude applications are effects linked to dimensional parameters like clearances and creepage distances due to reduced air pressure with increasing altitude. The electrical field stress through solid insulation under dedicated environmental parameters is depending on the device construction and is validated by test procedures according to the applicable product standards for application altitudes of 2000 m only. Above 2000 m the stated parameters U e, U i, U imp and I e for the devices have to be re-evaluated. With the application of the described correction factors and additional measures however the devices can be used at higher altitudes. For application altitudes up to 2000 m the correlation between the nominal voltage of the supply system and the rated impulse withstand voltage of equipment is shown in Annex H1 of IEC Correspondence between the nominal voltage of the supply system and the equipment rated impulse withstand voltage, in case of overvoltage protection by surge-arresters according to IEC Max. value of rated operat. voltage to earth Nominal voltage of the supply system ( rated insulation voltage of the equipment) Preferred values of rated impulse withstand voltage (1,2/50 µs) at 2000 m k Overvoltage category I III II I Origin of a.c. r.m.s. a.c. r.m.s. a.c. r.m.s. a.c. r.m.s. a.c. r.m.s. installation or d.c. or d.c. or d.c. level Load level Specially (service entrance) Distribut. circuit level (appliance, equipment) protected level 50 12,5, 24, 25 30, 42, ,5 0,8 0,5 0, / ,5 1,5 0,8 0, / , , 110, / ,5 1,5 0, /380, 230/ /415, 260/ / /600, 380/ /690, 415/ / , , , 380, , 440, , 577, , , ,5 1, ,

4 White Paper Low voltage products in high altitudes 4 The dimensioning of clearances aims to choose an air distance able to withstand the maximum peak voltage across the air gap between two parts at different voltages. According to Paschen s law, the behavior of air to withstand a maximum voltage value is in relationship with air pressure. Correction factors for altitudes above 2000 m are given in Table A.2 of IEC :2007. When these correction factors for altitudes above 2000 m are applied for determining the clearances, also the test voltage for the impulse voltage test is corrected accordingly. Therefore, the test voltage for the impulse voltage test is determined with the interpolation of Table A.2 of IEC :2007 and applying the formulas of of IEC :2007. correction factors ( extract) m Normal barometric pressure kpa Multiplication factor for clearances ,0 1, ,0 1, ,0 1, ,0 1, ,0 1,70

5 White Paper Low voltage products in high altitudes 5 Example A device has following ratings suitable up to 2000 m: U e U i I e U imp Pollution 3 Material class II current AC-1 / AC-3 8 k Intended application altitude: 4000 m U i consideration at 4000 m For installation at an altitude higher than 2000 m above sea level, the insulation level of external insulation under the standardized reference atmospheric conditions should be determined by multiplying the insulation withstand voltages required at the service location by a factor K a in accordance with IEC chapter Where H is the altitude above sea level (in m) and the value of m = 0,5 switching impulse withstand voltages. For the determination of the applicable atmospheric correction factor, it may be assumed that the effects of the ambient temperature and humidity tend to cancel each other out. Therefore, for insulation co-ordination purposes, only the air pressure corresponding to the altitude of the location needs to be taken into account for both dry and wet insulations. The suitability of the low voltage product in high altitudes is therefore depending on the following application specific parameters at the installation altitude: To be suitable for e.g m the K a can be calculated: H = 4000 m which gives a K a of 1,2787 The required U i (at 4000 m) is 690 * 1,2787 = 888 The power frequency validation for this value U i = 888 is to be performed with an AC test voltage of 2200 ac according to the table on the next page.

6 White Paper Low voltage products in high altitudes 6 Dielectric test voltage corresponding to the rated insulation voltage Rated insulation voltage U i AC test voltage(r.m.s.) DC test voltage b,c U i < U i < U i < U i < U i < U i 1500 a 3820 a For d.c. only b Test voltages based on , fifth paragraph of IEC :2007 c A direct current test voltage may be used only if an alternating test voltage cannot be applied. See also 3) b) ii) of Concerning creepage distances for an U i of 888 the table 15 of IEC applies. The table specifies the rated insulation voltage of an equipment or working voltage a.c. r.m.s. related to minimum creepage distances for equipment subject to long term stress. The following table gives for 888 an interpolated creepage distance value of 13,32 mm.

7 White Paper Low voltage products in high altitudes 7 Minimum creepage distances Rated insulation voltage of equipment or working voltage a.c. r.m.s. or d.c. b,c,d Minimum creepage distances for equipment subject to long term stress Printed wiring material Pollution degree Material groups All except All IIIb All I II III I II IIIa IIIb I II IIIa IIIb mm mm mm mm mm mm mm mm mm mm mm mm mm mm 10 0,025 0,04 0,08 0,4 0,4 0, ,6 1,6 1,6 12,5 0,025 0,04 0,09 0,42 0,42 0,42 1,05 1,05 1,05 1,6 1,6 1,6 16 0,025 0,04 0,1 0,45 0,45 0,45 1,1 1,1 1,1 1,6 1,6 1,6 20 0,025 0,04 0,11 0,48 0,48 0,48 1,2 1,2 1,2 1,6 1,6 1,6 25 0,025 0,04 0,125 0,5 0,5 0,5 1,25 1,25 1,25 1,7 1,7 1,7 32 0,025 0,04 0,14 0,53 0,53 0,53 1,3 1,3 1,3 1,8 1,8 1,8 40 0,025 0,04 0,16 0,56 0,8 1,1 1,4 1,6 1,8 1,9 2, ,025 0,04 0,18 0,6 0,85 1,2 1,5 1,7 1,9 2 2,5 3,2 63 0,04 0,063 0,2 0,63 0,9 1,25 1,6 1,8 2 2,1 2,6 3,4 80 0,063 0,1 0,22 0,67 0,95 1,3 1,7 1,9 2,1 2,2 2,8 3, ,1 0,16 0,25 0,71 1 1,4 1,8 2 2,2 2,4 3 3, ,16 0,25 0,28 0,75 1,05 1,5 1,9 2,1 2,4 2,5 3, ,25 0,4 0,32 0,8 1,1 1,6 2 2,2 2,5 3, ,4 0,63 0,42 1 1,4 2 2,5 2,8 3, , ,56 1 0,56 1,25 1,8 2,5 3,2 3, , ,75 1,6 0,75 1,6 2,2 3,2 4 4,5 5 6, , ,6 6, , ,3 2,5 1,3 2,5 3,6 5 6,3 7, , ,8 3,2 1,8 3,2 4,5 6, , a 800 2,4 4 2,4 4 5, , ,2 5 3,2 5 7, , ,2 6,3 9 12, , , , , a a b c d NOTE alues of creepage distances in this area have not been established. Material group IIIb is in general not recommended for application in pollution degree 3 above 630 and in pollution degree 4 As an exception, for rated insulation voltages 127, 208, 415/440, 660/690 and 830, creepage distances corresponding to the lower values 125, 200, 400, 630 and 800 respectively may be used The values of creepage distances stated for 250 can be used for 230 (±10 %) nominal voltage It is appreciated that tracking or erosion will not occur on insulation subjected to working voltages of 32 and below. However, the possibility of electrolytic corrosion has to be considered and for this reason minimum creepage distances have been specified oltage values are selected in accordance with the R 10 series

8 White Paper Low voltage products in high altitudes 8 U imp consideration at 4000 m Concerning the suitability of devices in applications at installation altitudes above 2000 m the U imp of the device has to be considered which is correlated to the device spacing. According to table A.2 of IEC a multiplication factor of 1,29 for clearances needs to be applied if the device is intended to be used at 4000 m. correction factors ( extract) IEC :2007 and applying the formulas of IEC :2007 m Normal barometric pressure kpa Multiplication factor for clearances ,0 1, ,0 1, ,0 1, ,0 1, ,0 1,70 For applications up to 2000 m a spacing of 8 mm is needed according to the table above. Minimum clearances in air Rated impulse withstand voltage U imp k Minimum clearances in mm Case A Inhomogeneous field conditions (see ) Pollution degree Case B Homogeneous field ideal conditions (see ) Pollution degree ,33 0,01 0,01 0,5 0,04 0,2 0,04 0,2 0,8 0,1 0,8 0,1 0,8 1,6 1,5 0,5 0,5 1,6 0,3 0,3 2,5 1,5 1,5 1,5 0,6 0,6 4, ,2 1,2 1,2 6,0 5,5 5,5 5,5 5, , ,5 4,5 4,5 4,5 NOTE The values of minimum clearances in air are based on 1,2/50 µs impulse voltage, for barometric pressure of 80 kpa, equivalent to normal atmospheric pressure at m above sea level.

9 White Paper Low voltage products in high altitudes 9 IEC / Table A.2 Minimum clearances in air m Normal barometric pressure correction factors for clearances m for U imp= 4k for U imp= 6k for U imp= 8k for U imp= 12k ,0 kpa ,0 mm 5,5 mm 8,0 mm 14,0 mm ,0 kpa 1, ,4 mm 6,3 mm 9,1 mm 16,0 mm ,0 kpa 1, ,9 mm 7,1 mm 10,3 mm 18,1 mm ,0 kpa 1, ,4 mm 8,1 mm 11,8 mm 20,7 mm ,0 kpa 1, ,1 mm 9,4 mm 13,6 mm 23,8 mm ,0 kpa 1, ,9 mm 10,7 mm 15,6 mm 27,3 mm ,5 kpa 2, ,8 mm 12,4 mm 18,0 mm 31,5 mm ,5 kpa 2, ,9 mm 14,4 mm 21,0 mm 36,7 mm ,5 kpa 3, ,1 mm 16,6 mm 24,2 mm 42,3 mm ,0 kpa 6, ,0 mm 36,7 mm 53,4 mm 93,4 mm ,5 kpa 14, ,5 mm 79,8 mm 116,0 mm 203,0 mm There are now two possibilities to address the use at 4000 m altitude. Declare a reduced U imp or validate with a U imp test or measurement: At installation altitudes of 4000 m with application of the correction factor a spacing of 10,3mm is needed to achieve a 8k U imp. As the device in the example is validated for 8 k, the spacing of min. 8 mm according to table 13 is proven. This means that this device can be used at 4000 m with a stated 6 k U imp only according to the table above (7.1 mm). To validate the suitable spacings for the final application altitude (see table above) it is possible to either re-test the impulse withstand voltage with the requested level or validate the requested spacings by measurement. In the example given, the 8 k at 4000 m need to be validated with an rated impulse withstand voltage of rated 12 k and a test voltage of 14,8 k (sea level) or 10,3 mm spacing measurement. As an additional option to improve U imp the use of Surge Protective Devices (SPDs) is possible. For the achievement of a necessary U imp for a given overvoltage category the use of suitable type 1/Type 2 SPDs is recommended in combination with other measures like increased space to conductive parts or other electric devices with opposite polarity or grounding.

10 White Paper Low voltage products in high altitudes 10 I e consideration at 4000 m At installation altitudes above 2000 m the reduced heat dissipation of conductors has to be corrected. The correction is also dependent on the ambient temperature. Concerning the reduced heat dissipation of conductors in high altitudes, reduction factors must be applied depending on the I e of the devices and the ambient temperature at the installation altitude. Reduced air pressure with increasing altitude lowers the air density causing the reduction of the heat dissipation. Assuming linear dependencies the following relations result: P loss h = P loss n x P n / P h IIh = Ie PPh/PPPP P loss ~ I² P loss h Power loss at altitude h P loss n Power loss at altitude n ( 2000 m) P h Air pressure at altitude h P n Air pressure at altitude n ( 2000 m) I h current at altitude h I e current at altitude n ( 2000 m) Reduction factors of the rated operational current I e (IEC :2007 and applying the formulas of IEC :2007): correction factors (extract) m Temperature C I e reduction ,0 1, ,0 1, ,0 1, ,0 1,48 Alternatively, appropriate larger wire sizes in combination with device separation may be used to correct the reduced heat dissipation in high altitudes. Regarding the thermal effects, particular attention should be paid to the following points: thermal exchanges by convection, conduction or radiation efficiency of heating or air-conditioning at installation site For some applications, the reduction factor for continuous current is insignificant. Equipment is normally not used at the limits of its continuous current capability, and the ambient temperature at higher altitudes is often lower than the 40 C ambient temperature according to the product standard unless otherwise stated.

11 White Paper Low voltage products in high altitudes 11 Recommendations The maximum continuous voltage (rated system voltage plus maximum overvoltage) must not exceed the calculated voltage capability of the device at the site altitude. Surge arrestors should be considered for all circuits to protect the installation, respectively the equipment, from transient voltages and to give the limit for the system voltage including tolerated overvoltage. The recommended back up protection of the SPD depending on the application has to be used. Example for use of SPD The table on the next page gives a recommendation for use of the devices related to specified device parameters and the measures taken at specific installation altitudes. This white paper is valid for the present design.

12 White Paper Low voltage products in high altitudes 12 Recommendations for specific altitudes TA<=60 C, AC-1, AC-3, pollution degree m 2500 m Device Ue/ Ui/ Ui test/ Uimp/k Measures max Ue Uimp/k Measures MS116, MS132, MS No EF19, EF No EF65-EF No T16, TF No TF65, TF No TF140DU No TA200DU No TA450DU No ESB24/40/ No B6/B No AF116 AF140 A210 - A300 2) No AF146, AF190- AF370, AF400- AF2650, A95 - A110, A145 - A No TA<=60 C, AC-1, AC-3, pollution degree m 3500 m 4000 m Device Ue/ Ui/ Ui test/ max Ue Uimp/k Measures max Ue Uimp/k Measures max Ue Uimp/k Measures MS116, MS132, MS no disconnect function EF19, EF EF65-EF T16, TF TF65, TF TF140DU TA200DU TA450DU ESB24/40/ B6/B AF116 AF140, A210 - A300 2) AF146, AF190- AF370, AF400- AF2650, A95 - A110, A145 - A no disconnect function 1) device separation 1) device separation 1) device separation 1) ) ) no disconnect function 0,88*Ie device separation 1) device separation *) device separation 1) device separation 1) ) Device separation: minimum distance of 10 mm to conductive parts or other devices with the same Ue 2) Data for AF09-16, AF26-38 and AF65-96 are available upon request

13 White Paper Low voltage products in high altitudes 13 Contact us ABB STOTZ-KONTAKT GmbH Eppelheimer Straße Heidelberg Germany You can find the address of your local sales organization on the ABB home page -> Low oltage Products and Systems Legal note We reserve the right to make technical changes or modify the contents of this document without prior notice. With regard to purchase orders, the agreed particulars shall prevail. ABB AG does not accept any responsibility whatsoever for potential errors or possible lack of information in this document. We reserve all rights in this document and in the subject matter and illustrations contained therein. Any reproduction, disclosure to third parties or utilization of its contents in whole or in parts is forbidden without prior written consent of ABB AG. Copyright 2017 ABB All rights reserved. 2CDC131118D0201 Rev. A