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TitleNEMA SM23-1991.pdf
TagsValve Copyright Steam Turbine Consensus Decision Making
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Table of Contents
                            NOTICE AND DISCLAIMER
TABLE OF CONTENTS
	Foreword
	Scope
	Section 1 REFERENCED STANDARDS AND DEFINITIONS
	Section 2 CONSTRUCTION
	Section 3 CONTROLS
	Section 4 PROTECTION
	Sectlon 5 FACTORY TESTING
	Section 6 SOUND PRESSURE LEVELS
	Section 7 PREPARATION FOR SHIPMENT AND STORAGE
	Sectlon 8 INSTALLATION
	Section 9 OPERATION AND MAINTENANCE
	Section 10 INQUIRY GUIDE (Authorized Engineering Information)
                        
Document Text Contents
Page 1

NEMA Standards Publication No. SM 23-1991 (R1997, R2002)

Steam Turbines for Mechanical Drive Service

Published by:

National Electrical Manufacturers Association
1300 North 17th Street, Suite 1847
Rosslyn, VA 22209

O Copyright 2002 by the National Electrical Manufacturers Association. All rights including
translation into other languages, reserved under the Universal Copyright Convention, the Berne
Convention for the Protection of Literary and Artistic Works, and the international and Pan
American Copyright Conventions.

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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Page 2

NOTICE AND DISCLAIMER

The information in this publication was considered technically sound by the consensus of
persons engaged in the development and approval of the document at the time it was
developed, Consensus does not necessarily mean that there is unanimous agreement
among every person participating in the development of this document.

The National Electrical Manufacturers Association (NEMA) standards and guideline
publications, of which the document contained herein is one, are developed through a
voluntary consensus standards development process. This process brings together
volunteers and/or seeks out the views of persons who have an interest in the topic covered
by this publication. While NEMA administers the process and establishes rules to promote
fairness in the development of consensus, it does not write the document and it does not
independently test, evaluate, or verify the accuracy or completeness of any information or
the soundness of any judgments contained in its standards and guideline publications.

NEMA disclaims liability for any personal injury, property, or other damages of any nature
whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly
resulting from the publication, use of, application, or reliance on this document. NEMA
disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or
completeness of any information published herein, and disclaims and makes no warranty
that the information in this document will fulfill any of your particular purposes or needs.
NEMA does not undertake to guarantee the performance of any individual manufacturer or
seller’s products or services by virtue of this standard or guide.

In publishing and making this document available, NEMA is not undertaking to render
professional or other services for or on behalf of any person or entity, nor is NEMA
undertaking to perform any duty owed by any person or entity to someone else. Anyone
using this document should rely on his or her own independent judgment or, as appropriate,
seek the advice of a competent professional in determining the exercise of reasonable care
in any given circumstances. Information and other standards on the topic covered by this
publication may be available from other sources, which the user may wish to consult for
additional views or information not covered by this publication.

O

NEMA has no power, nor does it undertake to police or enforce compliance with the
contents of this document. NEMA does not certify, test, or inspect products, designs, or
installations for safety or health purposes. Any certification or other statement of
compliance with any health or safety-related information in this document shall not be
attributable to NEMA and is solely the responsibility of the certifier or maker of the
statement.

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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Page 32

STD-NEMA SM 23-ENGL 1991 b470247 0524324 5 7 2 M

3.3.6.1 PRESSURE REGULA^

iacreases with decrease in steani flow.

3.3.7 Stablltty
Stabiîity is the capabiiity of the pessure regulating

system(s) to position the pressurt controlled vaIve(s) so
that sustained oscillations of the coaadled pressrno(s) ar
theeaxzgy~puttothesteamturbincarenotproducedby
the pressrire regulating SY-m drnmg m m undfx
mstaimîfiow demands or fauowing achange to another
value of sustained flow dtmand.

For Ihe pirpose of this standad ~ ~ i l . l a t i ~
~ b Y ~ p r e s s u r e r e g u l a t i a g s y s t e n i O f -
pressurtar of encrgy inpt are definedas the dinaence
b c t w c c n t h o s e e ~ w i t h t h e p r e s 9 u r e r e ~ s y s t e m
in semicc and thme existing with thepressrinregularing
system blocked or inaperstve.

338 Pressum~rolperformanee
A Class D goveniOring system (see 3.2) shall exhibit the

following characteristics when u t i h ú in a com-
conml system:

w . 1 changeinsuseainedspeedshallbe196maximum
for any sustamed change in flow within limits of 5% and
95% of maximum inductionor exmuion fbw guaranteed
forthatload.

Rcssueregulation iscoasideredpositivewhcnprtssure

NEMASEandard6-12-1985.

NEW-6-12-1985.

NEMA- 11-14-1985.

3.3.8.2 Steady state plessare regdation shall be 0.5 psi
(35 kpa) maximm or496 of ratedexbaust, extrauion.n

whichever is larger.
indmion plesule wtpressed m psig oc kPa (absolue);

N E W S U d d 11-14-1985.

3.3.8.3 sustained 0Scillat.i~ of canttolled pressure,
wiien aprating at C O I I S E B ~ ~ flow demaad op foiiowing a
change to another canstant flow, Shan notcxcetdoa psi
(1.7 kPa) ar 2% of thecon~fledpnsnireexptssed in psi
ob kPa (absolute); whichever is larger.

334.4 s ~ o s c i l l a t i ~ o f e i a e r g y i n p u ~ w h e n o p

NEMA- 11-14-1985.

&gatconstant flow demand or foilowing achange to
a n o r h e r ~ t f i o w , s h a U n o t e ~ 4 % ofratedpcwer.

338.5 The range of adjustment for ptsmre change(s)
shaü pennit adjustment of exhaust, extraction, or iaduc-
tion pressure betweem f5 p i g (35 kPa) M f10% of the
coamlled pressure expressed in psi or kFa (absolute);
whichever is iarger.

NEMA- 11-14-1û8!j.

SM 23-1991
Page 21

3.4 COMPENSATED CONTROLSYSTEM
Acompcrisatedcontral system is one which is proviâd

with intaconneciions between its conml mechanisms so
that the action dthe speed governar or of the pressure
qdator (s) also directly actuates the Othet control mech-
anism.

3.5 ELEC”K= GOVERNING SVSTEM

3.5.1 BaslcFeatures
An electronic govanhg system shaü include the foilow-

ingbasiccompooeprs:
1 Sensorswhichmeasureanoperat8igparamctaof

the turbineai system, andpoduce
electricsipah.

2 Agovamx which compares -(s) fnw dic sea-
gor(s) witb the seiectcd set point(s) and padeces a
Qgnal(s)fobthevalveactuator(s)tomaintainsystem
Parametebs-

3. An [email protected]) whicb positions the valve(s) directly
or though a a m l nucbamm * i n I e s p s e t o h
gov=SiEm.

one or mon of following parameters shallbecxxumlld

a. speed

c. othersforspecificapplicatiom.

NEMASEandaid6-21-1979.

bythegovemingsystem:

b. Eachinduct ion/exaact ion~

NEMASE8ndard 11-14-1985.

332-

a e p e n d i n g o n r a t i n g a o d ~

u . 1 CONTROLP~ES
Asignal selectmmay be incorporated intbegOVUIIOrt0

aüowthegovenwrrtoreceivesignalsfromse.veralscnsus
and tochoose the signal, which wiii result in thc piopa
valveopening.

Any paramm may be primary which the governing
as constant during IK)iTmBI operation. Sy- -

Any panunetex could be secondary which is i g n d as
lcQg asitisbelow the preset value.

3.599 CONTROLOF INDUCTION OR E X T R A m
The governor may be designed to control the low pres-

surevahrt(s) daninductim urextlxtion mine in con-
junctian wiíh the high pressure nive(~) . in this case, the
governar wnmls the flow to maintain the steam pressure
at each controlled extraction or induction opening while
simuuaneously controlling speed when necessary for the
appiication.

The following are accessories which may be selected,

. .

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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标准分享网 www.bzfxw.com 免费下载

Page 33

STDmNEMA SM 23-ENGL L991 6470247 0524325 409

Agoveniar with h i s capability incorporates featUtes to
adjust aii the ccmtroiied valves in mponse to a change in
any controlled parameters.

NEMAStandard 1-1-1991.

3.5.23 MISSHG SIGNAL DRECllON FEAtLIRE
nie missing signai &tecrion feature monitors all input

signahandaetaminesif they are in the cmect range. Any
signai that is out of range shwld cause immediate action
by the electmiic govexnor to enSure safe operation of the
tmbine, and should cause an alami indication.

3.52.4 SENSOAREDUNDANCV

8.5.2.5 OVU1SPEEDTmP

vided in addition to the primary trip.
nie overspeed trip feature in the governor can be pro-

3.5.26 other demonic governor accessories may be
available.

3.5.3 GENERAL
Caw shouid be talren in each installation to provide for

adequate wiring. in addition, elecmnic governors and

INPUTS

theirassociafedWiringshouldbepro~fmnheat,weat
and induced signais Local codes and area classif-
should be con-

Whenmi~basedturbinecontrolsystemsIrre
provided which interface with plant distributed control
systems, there may be some overlap of control loops and
confusion regarding inpuWoutputs. in these cases the pni
chaser and the vendor should mutually agree upon scapt
and responsibility spiiL Extemal selpoints can come íknn
the piant DCS but the turbine control loop should be
suppiieü by the Wine manufacturer.

A typid eiec&onic governor schematic is shown m
Figure 34.

3.6 AUTOMATIC START CONTROLS
Automatic start controls are avaiiabie for turbine and

driven machine. nie Wine manufacturer should te m-
suited for recommended equipment and pnicediires

Auaionred~neeringInfonnabon * 6-12-1mS.

NEMAStandard 1-30-1991.

Figure 34
ELECTRONIC GOVERNOR FOR PUMP OR COMPRESSOR CONTROL

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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Page 63

STD*NEMA Sf l 23-ENGL 1991 6470247 0524355 L 4 b

SM23-1991
Page 57

Factory Tests

Hydo test
No-load running test
DynamiCbalancerotor

site utilities
cooling w8t#: NOM Fresh Brackish
coding wata: other Tempcracure- -
Electrid supply: ddc

Conml(s) volts phase Hz
Motaro volts phase Hz

Air Supply pressiire

Site Environment

Elevation
Ambient tempexatwe Maximm Minimm

Environment Rdection at Site (S or i )
Enclosed SheltfXd outdooa
other
For monthss!crragepriortowartup
S = Storage
I = Installation

Remarks

Drawings and Data to be Supplied
certifiedoutlinedrawings
Recommendedspanpamlist
Instnicdonbooks No.
other

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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Page 64

MA

Copyright National Electrical Manufacturers Association
Provided by IHS under license with NEMA Licensee=Defense Contract Mgmt Command/5935922100

Not for Resale, 09/18/2006 02:36:51 MDTNo reproduction or networking permitted without license from IHS

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