安规网

标题: DSH 201A Characteristics of D.C. electric circuits for verifying normal operatio [打印本页]
作者: 小米    时间: 2012-9-5 11:26
标题: DSH 201A Characteristics of D.C. electric circuits for verifying normal operatio
DSH 201A
, ~0 Y0 `# P5 `$ s" I, h% l1 I& J7 A3 f) V. Y0 n% Y1 l
Characteristics of D.C. electric circuits for verifying normal operation and making and breaking cap ...: i: b7 U  b! A  Z: }9 c
-% i9 Z$ r5 B) y2 x* x" {
Generality
1 d- {$ m- X- A/ \
; O6 p# r' D& W9 p
To reach an acceptable test reproducibility, when verifying normal operation and making and breaking capacity, it is recommended that the test circuit has the following characteristics:
1 |- U5 [! x$ V/ A" _- Voltage drop
5 [( ]4 y- n2 N/ @The maximum voltage drop which should not be exceeded, when passing from noload, q1 C0 h& }8 y7 q3 t5 ]
to load condition, is 5% of the rated voltage.0 [* I4 |4 t8 F8 {
- Voltage ripple value
$ K7 k; D0 j3 T+ f( ~8 [( LThe supply voltage ripple, at no-load condition, should not exceed 5%.
, l- Z/ `' E8 I, r0 p; k# Q; B! ?NOTES:
; I8 l9 T- g. e5 r, w8 r5 Q1 h- Percentage ripple is given by r% = Vac/Vdc x 100, where Vac is the RMS value of the superimposed a.c. voltage and Vdc is the d.c. voltage.
, g& Z5 `3 X  m7 m/ }A simple way to evaluate the ripple is to use an oscilloscope, whose input is selected in a.c. for the measurement of Vac and in d.c. for the measurement of VDU.
+ r* ~" F/ K- u- The limitation of the ripple, which occurs, in practise, in rectifying converters, may be obtained choosing appropriately a rectifying bridge.0 a% y9 s. |' m7 {: o1 |! }8 g7 q5 A
- The use of a three-phase rectifying bridge, which gives a theoretical ripple of about 4,2%, complies with this recommendation.) h. ^' G+ |# [8 D8 L$ V
- Recovery voltage
" [  o( f# ^! k# QTest circuit, where:
; x& |$ ^. Y7 m- E is the supply voltage at no-load condition;
5 x- ^) g: `  U; {! ~- Li is equivalent to the different self-inductances of the supply as well as the stray inductances of the rest of the test circuit;
: B/ I" r! n* ~) Y" K) U- A- Cp is the stray capacitance of the circuit;. Z0 l, Q! r8 |$ t% d& Q% Z
- Rp is the parallel damping resistance.
$ t! T% u3 b, y7 b% QNeglecting the parallel damping resistor, Rp, the parameters Li and Cp should be adjusted so as to obtain:- u; f( J, c% q4 f* g
- Li = 2·10-3 H ± 25%, and( O, k" Q1 P# ~% _" a6 Z" ]
- Cp = 50 mF ± 25%., ^& ~) i8 v, Q1 Q+ F3 J3 ~- l
NOTE - Adopting the above mentioned parameters, all CTL Laboratories will get approximately
6 s8 t8 z( X- E. ?9 @! U4 t) a3 v- the same time constant T = Li / Ri = 2·10-3 / Ri;3 z' z6 F1 n+ H5 t) c# n% w
- the same oscillatory frequency fo = 1 / 2· (Li Cp)1/2  500 Hz.
5 M' `  D  @- W, L! B6 |# p
  V+ _" R3 [& [' T[attach]75565[/attach]( t) v  U2 n* M) }) N
1 N- m/ q6 Q; }, C
. F  h6 c6 T  _6 d
9 f; R0 m; |& T# T  W




欢迎光临 安规网 (http://bbs.angui.org/) Powered by Discuz! X3.2