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|  PDSH 1021
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| Short circuit and overload protection# J% s7 W3 o3 G5 k
| 15.24 d9 ]3 g( j1 y+ Y# {# X
| 61558-1(ed.1);am1 & 61558-1(ed.2);am1
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* V3 ]7 o# e; }* _% a, O. Y& uStandard(s):
, s( f8 n9 z8 q6 V/ Q* @IEC 61558-1
! Q& O) c, A5 B- B% |All editions
9 l& P( W5 @1 G3 P( KSubclause(s):8 N: K0 J& I8 Q0 Z1 D! j
15.2$ o% t9 U/ |" U; l
No. Year
' g0 O* t. Q2 M$ `4 ?& L2 aPDSH
+ E& v; R* [& D/ M1021 2010
8 J; h' h* A' r. \8 \# MCategory: SAFE Developed by: ETF5
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Subject:
7 ~4 p, O' N) i% UShort circuit and overload. y/ L* L* h# ~4 U8 H
protection* |5 A: l8 X V" A
Key words:( W) i" c: `+ R
- Transformers( \, b' M* V$ U
- Steady state conditions& R+ R8 h% R* N0 b$ w1 K( @ ]
- Short circuit
. ]9 e1 ~7 N+ ?4 e/ c" s6 o9 Q# LTo be approved at the 49th& d" z1 v( B7 q
CTL Plenary Meeting, in 20128 K/ n0 `+ y" c% M% O
Question:
3 L. G, c+ X- o4 gInherently short-circuit proof transformers shall be tested by short-circuiting the output windings until, T1 X; t8 Z* H* R) e7 k
steady-state conditions are reached.$ O. O( |: D- w+ r$ `
In the IEC 61558-1 “steady-state condition” is not explained. Referring to other standards for the meaning
+ x \- P6 P! H+ ~( Rof “steady-state conditions”. Or “thermal stability”. The thermal stability is the change of temperature of
+ Z; f( d. C. x2 ^+ s4 Wless than 1°C per hour. So the following questions arise:* d4 Z9 s' y& D! O' `0 _* q1 n: q
Is it correct to record the temperatures after one hour when temperatures didn’t change (more than 1°C/h)?" y& W3 L+ p1 D! w; ]# y
How shall an inherently short-circuit proof transformer be assessed when the above mentioned
. f& N- o0 u+ u* L/ t! erequirements are fulfilled, but the transformer is damaged 6h, after reaching the steady state condition, in
+ F Y/ c5 W1 L- Z: A( B! ya way where safety will be impaired (the transformer bursts).
& g3 _) w: D$ Q* u( K9 B$ w7 w* vDecision:1 m! P7 s. B, x# V1 D7 A
Yes. The transformer should not be accepted because the insulated materials are not corresponding to the( K+ i: ?1 h7 P! z- ^! {
insulation class of the transformer.0 }$ A9 k# A/ l1 p1 U( J/ w
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