ML18019A852

SER Confirmatory Item - Undervoltage Protection

ML18019A852
Person / Time
Site:	Perry
Issue date:	06/08/1982
From:	Davidson D Cleveland Electric Illuminating Co
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 9206170290
Download: ML18019A852 (3)

Text

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lr*nch "°.

Hr. Schvenccr, Chief.

. _Licensing 2.

D:lviston of i.tcenUnit .

u. ;S *. Nuclear Regulatory Co111dsdon

• Washington, D. c. 20S5S

Dear Hr. Schvencer:

Perry Nuclear ;over flant Doc~t No,.* so~440; 50~441 so conftniator:,.Jteti -

Undervolta&e.Pfotectton.

Further revi~w a11d analysis of the Class IE unden-oltage*protection1che11e has been conducted iii respe>nlie t~ FSAR *qu~ation 430.17*. A var~~ty of

• grid conditions were evaluated and computer daulaUoiie u1ed to etudy the !Jfff!cts of the 31,s 'itv ayit:em gr*d voltages in relation to the .

Clase IE bue voltage. .Voltage ,natyses in both .steady atute and :

transient. condition were perfcirnied. * * *

• Tt1c acc~l'tance criteria for t_he .ClaBS 1E

• bua volta1es "as baaed on *. ';j the followilig purchase specificatfon requirenaenta: . .. i

• i

t. .MotQrs are capable of starting fl'.om rea_t and accelerating their specified load with 75%

of rated nameplate voltage e~i&t{ng(dtiring acceleration) at the motor tenninala~ .

2. Motors are capable of. delivering their rated horsepower continuously. when .the .terminal voltage is+/- *0% of rated voitage. *

3. Hc.,t;ors are capab~:e of deltver{11g _their rated full load tprque at, 70% pf.rated *v~ltage *for infrequent

. five ml11ute Jnt~rval~. ** *

4. Ho tors are ~apable ot starttm~ ,dth 110% of rate'd .

~:voua*se 1i'i>pilea *aa: the motor*fenitnda~ * ** *. * *. *

• Rev.lev of aU steady *state cas~s. shows that the Cla88 1E busea sust:aine~

• n6 dcgradati<>n Qf voltage greater tiian lo% duriiig o~et~tion *t111der hll load, goo(:

11hutdovn.

• unit trip and LQCA.aod~li. i"'9 tranalent.*cu.e* ~ - *a *re.** ... *. *

• aevt!ire t:eilt :o:,* 'the auJclliat, .'ayateia~ 11 .!~),tl'tb' *c:~* *,µppor.t' *(.itonraf ~1~*1* .

• durin1 tli* *tarting J>f ~tor* *. *ln only oi,,d,f"t~tl caj,, *~~tlld: '<

0 cHd_.the'voltage .on. th~ Cl*** lEblltie.~ MC~dl!prt!l~~d beiow*ttae.0,5% J~~l for* atarttna Jaotorli. Ira thh worat. came aceilado Perry vaa c*af,derecl tcf be offline 'ta\'. 'startup or juat :trlpped:m~e 111~~ _other' 'iiaj'*qr: ....~..,tt..,

~its of the. CEl .syateti of0il)e and *a feedvater p...p(SOOO .-,) "* _Ul)ually started concurrent with receipt: c,f a LOCA aignal and the *-ltarieoui .

starttn1 ot *the. zero second LOCA 1o~da(21too *KW>. * :1.; thiil c*** the voltaae decays to 73%>ofmotor rate.cLvoltage.. . . . .

In evaluation of this atudy, thl! auxUiary-ayatem provide~ 1uftict1nt and reUable voltage riecea~aryJor litarting*Claiia I~ 11e>tora in*au ca***

except the highly improl,able:aequence deacribed above. In order to. provide further assurance of required ClaH IE operation even undf!r the IIOU adverse conditions, two levels of undervoltage protection will be provided .

for the Class l E buses.

• The first level of protection is. provided .to trip the offaite power

• source breakers arid'start and load* the diesel generator* in the caae of a lose of offsite power. A ,et of widervoltage relays vtll be provided for each ClaH IE bus, set to trip: at 86% of 110tor rated voltaae. The undervoltage relays, fol1ovtn1 a l second fixed tliie delay, wUi initiate the neceB&ary logic to r,onnect the ClaH lE buaea to the dteael generaton.

A LOCA signal initiates a diesel generator start signal, however, the .

• diesel geriei'ator breaker ia not closed unless an undervoltage condition .

exists~ . Hence, even if a LOCA aignal ts rec.eived during the l second time delay vhen voltage ta 86%, a system performance'within regulatory re-quirements is still met. A short time delay *111 required for this level of protection to allow time for fault cle~rtng operations to attempt to return the system to an acceptable level.

• The second level of undervoltage.protection will be provided to.insure the off site power source does not degrade to .a level. which* could jeopardize starting of Class lE motors in an adverie situation.

A second set of undervoltage relays will be provided for each ClaH lE bus, set to trip at 96% of motor rated voltage.* The undervoltage relays will energhe two separate time delay relays. The first time delay relay will initate undervoltage alarms apd a diesel generator start signal after 15 secon~s. The second tilne delay, will be set for approxlmately 5 n1inutes at which time the offsite source breakers: will be tripped and tile diesel* gener11tor loaded on the bus~.* .The five minute timer wtU also insure against motor overheating between 90% and 86% voltage *. The 1110tors purchased for Perry have perfol'liance characteristics.11uch that they can operate for. !nfrequerat 5 minute pedoda:at' 70% 'voltage.* . . , . .

This und~TV~ltage schemede(f.Cl'.'ibed above is presently being incorporated into O!,lr ~eli1BR* 'J,'estlng will al&O!be coriduct:ed to inilure.correct.reJay 11,tttngs.

• Th~ Unal :design and. settings viH be esi:abUshed after a review

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