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need to note the clause below:& E. Q k' {8 y: f. @8 y5 w& D
IEC60950:
3 n9 L: T6 N4 H+ e1.5.9.2 Protection of VDRs/ }$ l7 Z9 \' d& f$ S
For protection against+ n/ m' b0 ?& [2 u& G- q. |$ x( \
− temporary overvoltages above the maximum continuous voltage,
, u: v: f- f- Z9 E# W, @− thermal overload due to leakage current within the VDR, and7 t0 W2 X p. y2 t" I
− burning and bursting of the VDR in the event of a short-circuit fault,4 B( Y. F4 G$ A! r
an interrupting means having an adequate breaking capacity shall be connected in series with
# ^; Y* m3 U) Hthe VDR. This requirement does not apply to a VDR in a LIMITED CURRENT CIRCUIT.
5 s( U& i) o% J" Y8 j& p" R; T# s- q V6 y3 p3 `
IEC60065:# y) V# C+ \& ?3 C% h% E" P( [/ ?& h, V! X
– thermal stress
& Q2 Q: K( @& s* s3 k6 z: O/ {$ [For apparatus with nominal MAINS voltage of <150 V, the apparatus and a test resistor2 h, x5 H& x4 Q4 e* n+ Q3 ]3 ^; c; K% N
connected in series with the apparatus shall be energised from an a.c. source of 250 V.
6 e n/ h3 `+ ?8 k2 n3 N$ l( eThe voltage source shall be applied for 4 h or until the circuit path through the varistor
2 ?2 u1 Z8 e( [: r6 |opens for each of the test series resistance values: 2 000 Ω, 500 Ω, 250 Ω, 50 Ω. A0 `! u8 x7 g! c; [
separate apparatus shall be used for each resistor value, unless damage from the previous3 \4 e' a! e9 ~7 x. \4 Y; ?
test has been repaired.
7 |; m" U4 q9 B6 T3 k' M" QAt the end of each test, the apparatus shall comply with clause 11. |
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