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need to note the clause below:3 F1 {, p& i8 l8 a. M: o; W# n
IEC60950:, A6 C6 @: `, T% e7 H9 |
1.5.9.2 Protection of VDRs" Q4 l! J4 A' F& ^& c
For protection against
4 b; F8 T( |- i4 }− temporary overvoltages above the maximum continuous voltage,/ f' F! B" N9 ]: h7 H
− thermal overload due to leakage current within the VDR, and
. q3 \, G; a$ ~− burning and bursting of the VDR in the event of a short-circuit fault,
8 q- n2 |# v, C1 U1 P% x/ Dan interrupting means having an adequate breaking capacity shall be connected in series with
) N, B% o% l0 w0 r9 y6 Zthe VDR. This requirement does not apply to a VDR in a LIMITED CURRENT CIRCUIT.! `1 v3 F4 w' t9 ]
2 ~# n/ Q3 F( Q) I# \ X( X$ b, fIEC60065:0 v$ q% W5 Q5 ^) `5 z9 ^. [- Y
– thermal stress
* K5 I2 \$ x' ^) S" VFor apparatus with nominal MAINS voltage of <150 V, the apparatus and a test resistor2 x; q$ Z5 N# Z4 o
connected in series with the apparatus shall be energised from an a.c. source of 250 V.+ ~: ^0 L) G# n! F; b* w* i
The voltage source shall be applied for 4 h or until the circuit path through the varistor3 f; L% r! W4 i* a# j1 Z
opens for each of the test series resistance values: 2 000 Ω, 500 Ω, 250 Ω, 50 Ω. A
3 l" p* O! t5 h. x! Wseparate apparatus shall be used for each resistor value, unless damage from the previous- N# z0 C. q7 a
test has been repaired.
4 R+ [( X5 n$ z7 PAt the end of each test, the apparatus shall comply with clause 11. |
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