DSH 709/06 Short circuit and overload protection

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广东安规检测
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DSH 709/06 * e: b7 N! O  m+ D6 m

Short circuit and overload protection 6 B" i0 I0 M* D& A! j% n6 f) z6 x5 o

15.2

61558-1(ed.2) : @9 u8 h8 p: B1 P6 v  z

' Q: _* G% _* c& y7 z9 ]- u/ GStandard(s): IEC 61558-1/2005 No. Year
/ [8 o: g! l& ?( XDSH
0709
4 X9 Q7 n6 F9 A7 Z$ j2008
# F! b* C; l+ J# jCategory: SAFE
Subclause(s): 15.2
" k+ f7 c+ n! ~& K: h& R4 L+ _  A2 bDeveloped by: ETF5
OSM/LUM
8 y7 g. Z* V0 Q8 f. P" U- u% `& PSubject: Short circuit and
overload protection
Key words:
- Transformers
' U# S. g8 z) Z/ S  X% \$ Z& T$ i6 w- Steady state conditions
5 t$ F2 y! L/ O6 e  j" l- Short circuit
3 ~0 g% u" N0 K8 ?+ ^$ J& b: PDecision approved at the
$ x) f9 @/ h# T3 l46th CTL Plenary Meeting,
in 2009
Question:
Inherently short-circuit proof transformers shall be tested by short-circuiting the output windings until
steady-state conditions are reached.
In IEC 61558-1 “steady-state condition” is not explained. Referring to other standards the meaning of
/ K* n* w8 I) H  @7 @“steady-state conditions” or “thermal stability” is that the change of temperature is less than 1°C per hour.
+ B0 }6 v2 v: J. B8 Y; R  USo following questions arise:
1) Is it correct to record the temperatures after one hour when temperatures did not change (more
8 l0 ^& f8 a8 [7 `than 1°C/h)?
2) How shall an inherently short-circuit proof transformer be assessed when the above mentioned
requirements are fulfilled, but it is damaged 6h after reaching the steady state condition in a way
! P, p1 h7 |" j/ v, N$ t& owhere safety will be impaired (the transformer bursts).
Decision:
1) Yes.
2) The transformer should not be accepted.

; ]1 v! C! s7 F$ p0 B) M# U