OVERLOAD CURRENT PROTECTION OF MERCURY-ARC RECTIFIERS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600280537-5
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 4
• Document Creation Date: December 22, 2016
• Document Release Date: October 12, 2011
• Sequence Number: 537
• Publication Date: January 26, 1950
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/10/12 : CIA-RDP80-00809A000600280537-5
COUNTRY USSR
CLASSIFICATION COIHFIIIFti?P7AL ~~Ci'd~(ti Yli ~~
CENTRAL INTELLIGENCE AGENCY
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
50X1-HUM
DATE DIST. '?fib Jan 1950
NO. OF PAGES b
SUPPLEMENT TO
REPORT NO.
THIS IS UNEVALUATED INFORMATION
THIS DOCINIST CONTAINS INMSSAr,ON AAICTISS ma NATIONAL DIYINIS
OI TNT 051"g STASIS ?ITII^ The SU41a4 01 OSMOSASI ACT 00
S. f. C., TI AAN II. Al ASII1IN. in TI+SNg1+NaN 0I Till IIrILATIO^
1111!1150 ST SLAW. IN IMA., 11AN.11 . A% ODp'tl00 01 THIS POSH II fW# ILO. ~i IID
ODBRL0AD CTJRRE1T PR0i"EI1ION OF MESCUR?'-ARC aCTIFIEflS
Engr M. M. Feyerwark
"ruuhele tromontazh"
LA Digest
The basic requirements for the protection of mercury-arc rectifiers from
exceem currents are rapid action, selectivity, and. maximum sensitivity. High-
speed protection is necessary in view of the sharp lose in vac nun due to th,
tiu lag which occurs when the ere-backs in the rectifier are cut off.
A positive solution of the problem of high-speed protection simultaneously
satisfies the requirement of selectivity, when damtage occurs in the high-voltage
alternating current circuits. Consequently, the nature of the protective action
against this type of damage will not be discussed here. The requirement of m ri-
mum sensitivity is stipulated by the fact that relatively weak currents may arise
in the primary rinding of the transformer when the arc-backs originate.
In view of frequent occurences of arc-barks, protection for this form of
abnormal condition must be very reliable to prevent deterioration of the inter-
nal condition of the rectifier. Such deterioration W result from delayed
protective action or strong actuating current in overload relays.
Nxisting Msthods for Achieving Protection
As protection against excess currents, caused either by breckdWns in the
transformer or by arc-backs, two-phase overload protection has generally been
used, operating with tins delay or instantaneously (cut-off). For manual con-
trol with circuit breakers, direct-acting overload relays built into the break-
er drive mechanism were frequently used.
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CLA SIFICATION C044FIIfIA.L
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Sanitized Copy Approved for Release 2011/10/12 CIA-RDP80-00809A000600280537-5
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50X1-HUM
CONPJ)EETIAL
The actuating ct=. ent )f the cut-off relay must be greater than the mag-
netiLing current kick which mey ezise when the t:,ensfcrmer is ew;.tched or. In
practice this current has four to ten timed tat value of the nominal current.
Therefore, a protective scheme in which the actuating current is large enough
to permit evitching on the traneformer, with specified values for the iagnet-
izing current kick,., ::e inadequate from the standpoint of protection require
nets agaiast a arc-brscks in the rectifier, where the value of the breakdown cur.-
rent ir. the p:?rr.y winding of the transformer m&,y, in the initial stages, be
lower than the specified vvlues for the rajnetising current in some cases.
Further re, good results cannot be obtained from a time-delay protec-
tive device vhi_n ' n operate at lower actuating currents (due to the rapid
decreeee in the magnetising current kick) since instantaneous action of the
protective ci.eaic7 is the basic .:requirement for counteracting arc-backs.
The protection given by the two relays in tvno-phaae protective schemes
maybe inedequabe due to rebalance in the breakdown phase currents. There-
fore, three-phase protection should be used in such caeee. This does not re-
quire three-current tranafor ra; a1:1. that is needed is the inclusion of a
third relay operated by the sum of the currents of two phases. The effect ie
the same as that of including three relays operated by the phase current of
three c rrrent tr'nsf ormerr .
The circuit diagram bel.ov aho*ee a proposed scheme for overload current
protection which is largely free of the defects mentioned above. Protective
time dr ey is used only ?-1'en the transformer is switched on. t',=<
protective device operates without time delay, vhi--h makes it possible to sa-
lect the actuating current of the overload relays corresponding to the mini-
mum value of the breakdown current during arc-backs at the anodes.
Sanitized Copy Approved for Release
2011/10/12 : CIA-RDP80-00809A000600280537-5
 Sanitized Copy Approved for Release 2011/10/12 : CIA-RDP80-00809A000600280537-5
J -P7ptih butt-)n
3:&&r."'Eris L
SO-Cut-nut, eoie:ac:i f,.,r breske
V-Block onntac: for C:S:h oui t lre t1i:
ior " e f_}rSYr
retrons ate ,vuppiieI by the pant. So fear ae t.s kl'aovn to the author, at pree-
ant, there is no oper,stione,1 verificvrticrn cn the use of this device But .if it
_1:oven reliable in pr,,scticr., ar& gri.l~. protection Yatisfiey the given rsquire-
menta, the role of c-rexload protection in the sense of urotection from er e-
b>tcks will become leas important, since proper end protection, according to the
"Rules for the prrrtion of _rnduetziek1 Ina a irtione," must function in at least
75 percent of the saes of airc-backs,. In a,4%i:ion, there are grounds for an-
ticipattag, when gkid protection is us-d, that tte insta:ii&tion will. not be
switched off as D. zeCUI. :-f ovsr.,oe prot"5,;1:,.on be=coin=: of the great sensitivity
of the thyr'atrons and the greet potputia' .I 4pplied
to the rectifier paid q.
Protective Devices (,pea tine on ~7.terurti 'urgent
When i:re:e are uo independent eourcee of operating con cot, the prvFcued
protection scheme corn he operated on exl:`,ernnting c r ent.
In this case, the basic protection of the tra..nuforner against interph_nse
short circuits in the windings and at the outlet leads in effected by mesna of
direct-action rela'e which cut out the transfor er without time leg. The ac-
tuating current of these relsye is seliec.ted according to the mar_imum value of
the transformer current malgn?:tization kick vbich is determined e.mprrimentslly.
For protection from arc-backs, a sepw e,te re''>sy system 1e provided which,
when orerated on direct current, ;e:r.~,e es protection against all types o' break-
downs.
The operating circuits for arc-back protection are fed from the i;i.ternuting
current supply lines through selenium rectifiers connected in A Prate ful7vave
circuit. The output voltage of it Type VS-6 selenium rectifier, when supplied
with 220-volt alternating current, i. 160 volts with a load of 2 amperes. This
operating voltage is quite peel a t,;n for rapid closing of the iate mc3ie~te
relay and the cut-off solenoid, which have coils with a nominal voltage of 110
volts. The blocking relay with a nom ueL_ ecii voltage of 226 volts also oper-
ated i.ariabiy, it: core ?e1ng c i1ed in act to volts.
PT-DENTTAL
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 Connecting ~a1_a~cm rectifi?re :tire:?.tly to the 2^^-.volt phase voltage of
the alternate current net-aork is anti;se racle as there voald then be a perma-
nent ground on the operatir.& cir..'t.., Au let rueltete transformer should there-
fore oe pravried, e l- i:?-ag :netall l^t between alternate current ens
operating circuits. A eingle re t fytr.g cir;.''t of suitable power can bt used
Although the buebar voltage tt a E-lip kiiovo't substation may fall dulr-
ing arc-backs in a mereiry re:.tifier, it is praet:rally imposeitle for the
alternate current operated protection to faL1, wince a voltage margin gas pr:}-
vided for in the cir.:_, t, as deser:t'ed ebove, h`herefor:, the protection is
The holding ..il o f the 's, -. R,;e i ;.t r't= :e : al I,, I from the
sAleni-rn r_':aftSr 'h la ' ..`r ?P.4 L-7- f't 'f thie
ee.ipment can be fed from the
Opening cf the aa.t:ma*.i: 9.e-:'_-.-. :C.`: rh.rt in the aiter:a.te
current network, a^c:mpa~.Lei by ;:=s--, : t..zge irop._ are very rare, when the
hol'li.ng call is a, doe pit ' ._.... : tl,i kes not effect th-
1.. Relay proteett; _ "rpre ry-a-: r;-;:ti flars :y.u, as s rc'_= be oper-
ated or, alt:-rn? tine c~-errant., ce.r?,e `. = F i, ;,1d r. z d ah.en et:.reg but, -
tr--ties, ii-tallea ru ,, :. :c+ .--,? .ei ::h the n!e?rc.tu-r ar,, rectifiers,
are available.
2. Whether el:er_eate -'xrre.nt er '..-.... ..erreit is u,er?? rnexlenln eanei.-
ti-rity to are-bacico; in the rentifier is r _ .. -..-. This involve;, the ,._c of
three-.phas. . rerloaa pr- -'.ic :a h e :me i.t.:;r_o"k to cl:.~a for '.he ma
c-crre_. t -k. tt- _ tt a _.. it oc ..
nrTr ra eal
IIr1c C t9. ~
Sanitized Copy Approved for Release 2011/10/12 : CIA-RDP80-00809A000600280537-5