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| DSH 401
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| Mains supply transformers: Short Circuit and Overload tests
6 `4 a) G8 Y% T! g! _* l% c( H | 57.9.1$ z" _1 X* ?/ Y! p- \
| 60601-1(ed.2);am1;am2
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/ Q: C# i2 `1 h6 `9 jStandard(s)- (year and edition):0 J( A' z& E3 S4 l1 L' X9 s& {- O, @
IEC 60601-1:1988 Ed.2 Am1+Am23 _1 I" o& }2 M, h8 Y- Z
Sub clause(s): 57.9.1
$ [8 ~" H5 G( L @' u, sSheet n°: DSH-401
9 A9 y: T' h: \Subject: Mains supply transformers: Short Circuit and Overload tests
; m2 Y' |- S* P1 t! jKey words: Over-current, protection, overload/ t5 P. [, B9 @
Confirmed by CTL at its 39th meeting, in Cologne" A0 j# ~* R6 o7 Z; G: G6 K; u; r
Question:: n# K" S! |' w' Y2 O1 R- }/ q; _
Secondary circuit OVER-CURRENT PROTECTION is the first active component on the W* n2 S4 |8 t2 F
secondary side of a mains supply transformer. Is the overload test performed before or after the
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Insufficient transformer winding crossover insulation and secondary circuit CREEPAGE1 P* t. H' e# m9 ]4 @$ z2 g: @
DISTANCES and AIR CLEARANCES causes transformer winding to short-circuit and exceed0 e$ C$ q$ z1 {0 s( ]% ^$ j# I: P
allowable temperatures.( t- S2 b- \+ `5 T- l. W
Decision:7 |- A' w5 F9 S, M7 @# t
If the possibility of a short-circuit exists before the secondary OVER-CURRENT PROTECTION l3 N0 t$ Y L
device (e.g. failure of basic insulation between winding or detachment of the wiring) the short. Z/ t$ d3 E# I8 S# y& W# C
circuit test should be conducted at the exit of the wiring from the transformer.! X; m1 w' o. A5 w4 C8 o$ {2 t% _& H
(N.B. Similar recommendations can be made for batteries and their protective devices)
3 y5 o9 c$ z% n# qThe overload test however must always be conducted after any secondary OVER-CURRENT
6 x' O; s0 j; T8 o3 ]1 qPROTECTION device (conform clause 57.9.1b) providing that the conditions of sub-clause0 X d9 I1 G; D, w; i
57.9.1. second dash are fulfilled.8 W" k; K5 L/ a
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