PDSH 992 Extra safety circuit equivalent to SELV or double/reinforced insulation

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PDSH 992 , d; V5 f  \% a; h% @

Extra safety circuit equivalent to SELV or double/reinforced insulation ) [4 @/ R! z3 a0 |# @6 ~

12

60570(ed.3);am1;am2 & 60570(ed.4) : q! d7 C2 {8 ]9 d9 |

Standard(s):
IEC 60570 All editions
$ q- B# t4 T5 u' W" O8 c+ Y9 fSubclause(s): 12
No. Year PDSH 0992 2010
Category: LITE Developed by: ETF5 OSM/LUM
Subject:
+ u: J/ m$ E! P& ]4 j. S  uExtra safety circuit equivalent to SELV or double/reinforced insulation
( j( h9 X+ k: L; I* aKey words:
9 N( i, {( i# h: v( G- SELV condition
- Electronic means
- IEC 60364-4-41 / IEC 61140
' n2 v$ e: Q0 rTo be approved at the 49th CTL Plenary Meeting, in 2012
* ~5 D2 a0 x5 i) n  x" OQuestion:
; q) ?  w9 L  W. D8 u# k  cA client wants to combine a 230 V track system (according to IEC 60570) with a bus track system, which
4 K6 P' J: k: A0 |# gtracks are accessible. Consequently the bus-tracks may be supplied by a SELV source only, or connected to
circuits, which are insulated from live parts by double or reinforced insulation. Due to the fact that both
, G/ L- O+ a5 s- WDALI systems (or similar systems) and control systems of electronic ballasts do not comply with the
; b- _* L- U% C: vrequirements of double insulation, our client created an additional safety circuit between the bus-track and
" |- a# ?- s! Y- p; l  ]DALI system/electronic ballast. The extra safety circuit consists of six zener diodes (>50 V) and four
  m1 q: k' X5 o7 E2 f1 ~* }: I  s0 k6 Pfuses (250 mA). The diodes guard the system to voltage higher than 50 V and the fuses protect the system
against high currents. In this way SELV conditions are guaranteed.
# v+ @2 E6 x. ^2 SDecision:
In principle the SELV condition can be reached by electronic means at least according to the standards
IEC 60364-4-41 and IEC 61140.