Function and use of arc fault protection systems in low-voltage switchgear installations Rainer Ziehmer, DEHN + SÖHNE GmbH + Co.KG. © 2014 DEHN + SÖHNE / protected by ISO 16016 Rainer Ziehmer Product Manager Safety Equipment DEHN + SÖHNE GmbH + CO.KG. Hans-Dehn-Str. 1 92318 Neumarkt Tel.: +49 9181 906-1305 FAX: +49 9181 906-1219 [email protected] www.dehn.de © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection Arc fault risk for persons Risk Arc faults cannot be completely ruled out High risk of damage to persons and installations Direct effects of arc faults Thermal effect Incident energy / high temperature / hot particles Radiation effect Flash / electromagnetic radiation (IR … UV) Dynamic effect Pressure wave / sound / forces Toxic effect Pyrolysis / toxic gases / metal vapours © 2014 DEHN + SÖHNE / protected by ISO 16016 12.11.13 / 7087_D_1 Arc fault protection Arc fault risk for persons Reduction of arc fault effects to an acceptable level Reduction of the arc energy by limiting the arc duration Short-circuiters allow to considerably reduce thermal and toxic effects Technical solution: DEHNarc arc fault protection system © 2014 DEHN + SÖHNE / protected by ISO 16016 AS Seminar Störlichtbogenschutz 16.12.13 / 7087_D_2 Protection of persons during live working from the effects of an arc fault: Example 1 Operating time of a 630 kVA gTr fuse (400 V, 909 A) Prospective short-circuit current Ipros for 630 kVA installations: 16 kA to 23 kA Arc voltage Uarc in 400 V low-voltage systems: up to 200 V Arc current Iarc: up to 50% lower than the prospective short-circuit current Pre-arcing time of the fuse in case of a 10 kA arc: 200 ms => tarc > 200 ms In this case, the energy Warc of a three-pole arc is calculated as follows: Warc = √3 • Uarc • Iarc • tk = √3 • 200 V • 10 kA • 200 ms = 693 kJ 400 V/ 630 kVA 909 A gTr arc faults LV power distribution 400 V / 909 A / gTr L1 L2 L3 200 ms PEN Parc ≈ 3.5 MW 10 kA © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 07.02.14 / 7284_E_1 Protection of persons during live working from the effects of an arc fault: Example 2 Limitation of the arc energy in a 630 kVA installation (400 V, 909 A) An arc fault (for example 10 kA) is detected within about 3.5 ms A three-pole metallic short-circuit is initiated within about another 1 ms The arc power is reduced by short-circuiting the voltage after approximately 0.5 ms The arc energy Warc of a three-pole arc fault is reduced by the factor 40 to: Warc = √3 • Uarc • Iarc • tk = √3 • 200 V • 10 kA • 5 ms = 17 kJ 400 V/630 kVA DEHNarc short-circuiter 909 A gTr arc faults LV power distribution L1 L2 L3 PEN KST Parc ≈ 3.5 MW DEHNarc STG © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 07.02.14 / 7284_E_2 DEHNarc mobile arc fault protection system Effects without arc fault protection system Direct thermal exposure without protection: ∆Tmax = 77.9 K Ei0 = 432 kJ/m² “STOLL curve “ Without arc fault protection system: Arc current of 6.2 kA for 500 ms © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 05.11.12 / 7150_E_1 DEHNarc mobile arc fault protection system Principle of the arc fault protection system Significant limitation of the thermal effects of arc faults: “STOLL curve“ ∆Tmax = 1.23 K Ei0 = 638 kJ/m² With arc fault protection system: Arc for 8.3 ms and short-circuit current of 7.7 kA for about 500 ms © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 05.11.12 / 7150_E_2 Protective effect of the DEHNarc arc fault protection system Significant limitation of the effects of an arc fault: Toxic effect: Pyrolysis, toxic gases and metal vapours are minimised © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 07.02.14 / 7285_E_1 DEHNarc mobile arc fault protection system Arc fault detection Multiple redundant detection by means of three sensors Response to light variation 9.000 lx / ms or absolute illuminance 100.000 lx Unaffected by extraneous light Suited for open installations Monitored fibre optic cable Typical detection times Parc ≥ 100 kW ⇒ 20 ms Parc ≥ 400 kW ⇒ 13 ms Parc ≥ 1 MW ⇒ Parc ≥ 3 MW ⇒ 3.5 ms 7 ms © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 07.11.13 / 7151_E_1 DEHNarc mobile arc fault protection system Fixed components 1 2 Wall-mounted pair of light sensor supports (sensor 1 and 2) C-rail-mounted light sensor support (sensor 3) 4 NH fuse disconnector (4) 3 © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 30.01.14 / 7152_E_1 DEHNarc mobile arc fault protection system Mobile components Control unit with three light sensors, power and control line sockets Disconnecting blade Short-circuiting cartridges Junction piece Technical data Nominal voltage 230/400 V 50 Hz Prospective short-circuit 2 – 25 kA current Max. short-circuit duration 70 ms (at 25 kA) Typical response time 5 ms (at 65 kA) © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 30.01.14 / 7153_E_1 DEHNarc mobile arc fault protection system Mobile arc fault protection system ensures the protection of persons and installations during live working The direct effects of an arc fault under fault conditions are actively reduced to a minimum Easy initial operation of the mobile arc fault protection system on the prewired low-voltage equipment © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection Störlichtbogenschutz 29.01.14 / 7156_E_1 Components of the DEHNarc mobile arc fault protection system – Design of the cartridge trigger connection air gap movable electrode spring melting tube © 2014 DEHN + SÖHNE / protected by ISO 16016 Arc fault protection 07.02.14 / 7285_E_1 Arc fault test 65 kA low-voltage switchgear installation © 2014 DEHN + SÖHNE / protected by ISO 16016 AS Seminar Störlichtbogenschutz 07.02.14 / 7286_D_1 Principle of DEHNshort Point sensors and current transmission detection device S4 S3 S2 light sensors S1 fiber optic output short-circuiting unit T1 circuit breaker >I © 2014 DEHN + SÖHNE / protected by ISO 16016 current transformer RZI 240114 Arc fault protection system Maximum availability of the installation following an arc fault thanks to fast recommissioning Active arc fault protection system protects persons © 2014 DEHN + SÖHNE / protected by ISO 16016 AS Seminar Störlichtbogenschutz 03.02.14 / 7163_D_1 Thank you for your attention © 2014 DEHN + SÖHNE / protected by ISO 16016
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