Presentation (Synch Condenser)

8/19/2019 Presentation (Synch Condenser)

1/60

ENHANCEMENT OF VAR

MANAGEMENT IN CESC

NETWORK

(Operation of NCGS units asSynchronous Condensers)

A PRESENTATION BY VAR ENHANCEMENT TASK FOCE


2/60

1.Introduction

2.Exercises that have been carried out

3.Path forward to execution


3/60

Introduction


4/60


5/60

Q: What is the effect of low system voltage? A:

a) There is a possibility of VAR drawal from SEB.

~ ~CESC SEB

VAR FLOW

V

~ ~CESC SEB

V1 V2

V1 < V2

b) Low system voltage may lead to grid voltage instability and the wholegrid may collapse. Such grid failure at Southern and Western grid tookplace, a few years back due to low voltage.

c) Low voltage may lead to rotor angle instability while overloading agenerator.


6/60


7/60

Q: What is the limitation in method 1?

A:

• In the process of increasing excitation, overall MVA delivered by thegenerator increases (provided the active power delivered remains constant).

• This increases the generator current and often crosses the rated limit.

• However increased lagging load can be met at the cost of reduction inactive load.

• Hence contradictory in nature.

• During peak summer evening load, both active and reactive becomesequally important


8/60

Resort to Method 2

(Disadvantages of Cap Banks)

• Several cap banks have been installed. But supply / demand reactive power

is so much impaired, that we are not yet been able to manage the reactive

demand.

• The cap banks are prone to failure due to harmonic overheating andelectrical resonances.

• Switched capacitors are added to the system in steps which can develop

over voltages.

• In addition to abrupt system changes, switched capacitors cause voltage

transients on the electrical system during this switching steps

• Life expectancy of a cap bank can be in the range of 3 – 5 years.


9/60

Resort to method 2(Advantages of Synchronous Condenser)

•Step less smooth control.

•The system produces no switching transients and is not affected by system

electrical harmonics.

•Some harmonics can even be absorbed by synchronous condensers.

•Synchronous condensers will not produce excessive voltage levels and are not

susceptible to electrical resonances.

•Synchronous condensers are also very reliable and require little maintenance.

•Initial cost is comparable to switched capacitors and is considerably less than

static VAR compensators.

•Life expectancy is in the range of 20 – 30 years.


10/60

With a view to the advantages of

synchronous condensers and imminent

retirement of NCGS Units as generators,

conversion of the NCGS units tosynchronous condensers is being thought

of.


11/60

A task force comprising of the following

officers has been formed for the purpose.

1. P.K. Guha (Manager, SGS)

2. J.R. Bhattacharjee (Manager, Testing)

3. S. Samaddar (Manager, CTM)4. P. Dey (Asst. Manager, NCGS)


12/60

What is a Synchronous Condenser?

A synchronous motor designed to run

unloaded and over excited to serve as a

load on the supply system of a very low

leading P.F. is called a synchronouscondenser.


13/60

Typical characteristic of a synchronous condenser

a) Large synchronous reactance (Xs) to minimize active

load on the system

EV Active Load= --------- Sinδ

Xs

b) Large field winding for over excitation

c) Typical P.F. at full load = 0.02


14/60

Exercises that have been carried out


15/60

• As a first step to study the feasibility of conversion of NCGS 30 MW unit, the

capability curve of the machine has been developed.

•To develop the capability curve, an old OCC and SCC characteristic curve has

been retrieved from Testing Department archive. This is required to find out the

synchronous reactance of the machine.

Specification of NCGS 30 MW unit

MW 30

MVA 35.3

Volts 33 KV

Stator Amps 618 A

PF 0.85

Star Connected, 50 Hz 3000 RPMExcitation voltage 300 V

Rotor current 360 A


16/60

NCGS #2 (OCC-SCC)

0

5

10

15

20

25

30

35

0 50 100 150 200

Rotor Current (A)

S t a t o r V o l t s ( K V )

0

100

200

300

400

500

600

700

S t a t o r C u r r e n t

If1 = 100 A

180 A

IG = 618 A

If2 = 180 A

SCR = 100/180 = 5/9 = 0.55

Xs = (1/0.55)x100 % = 180 %


17/60

Capabilty

Chart

Of

NCGS

30 MW

Machine


18/60

Inferences derived from capability curve

•The capability curve reveals that machine can deliver 29 MVAR

(max) at 260 % excitation which corresponds to the maximum

rated current of 260 A of rotor current.

•NCGS data shows that, of late the rotor has handled 210 Awithout any problem.

•Keeping a margin of 20 A rotor current (meaning 240% excitation

or 240 A rotor current) and considering 0.5 MW active power loss

in the machine, it is evident from the capability chart that themachine can deliver around 26 MVAR.


19/60

Speeding up of the machine

Once the reactive capability of the machine is

evaluated, the next greatest challenge is to raisethe machine to synchronous speed and

subsequent decoupling of the prime mover after

synchronisation.


20/60

Some practical means of speeding up the

synchronous condenser

a) Using the steam turbine

b) Using a pony motor (may be a low slip induction motor)

c) Using the existing DC exciter

d) Using another generator


21/60

Mr. S. J. Lishman of Siemens, UK, has answeredseveral questions raised by CESC in connection

to conversion of NCGS generator to synchronous

condenser. The question answer session is shown

in the next few slides.

Note:Mr. Lishman has commented that the following notes are

intended as guidance comments only and do not make any

particular recommendations for which system would be more

suitable for New Cossipore unit 1.


22/60

Q: We intend to remove the LP spindle and fit a dummy shaft, remove enough

HP turbine blading such that the output of HP is limited to running the generator

rotor to speed. Once synchronised the steam supply will cut off leaving the HP

blading to run in the air. Is this option possible? If so,

•How much HP blading needs to be removed to power the machine to speed?

•Is vacuum necessary with the remaining blades or can they run in air?

•Can the condenser take resulting positive pressure?

A: Generally for smaller machines it takes around 6% of the mass flow of steam

to drive a machine up to full speed no load. However, regarding how much of

the existing blading would be required to do this is not a simple calculation as

there are potential windage heating effects etc to be considered. Coupled with

the fact that the HP blading is old design 600 series we believe this would be a

novel approach to the conversion to synchronous condenser operation and

therefore a design study would be required to confirm whether this method ofconversion would be possible. Given that this method also removes the

possibility of the machine ever again operating as a turbine generator it would

be better to consider other less destructive options for the conversion, as

above. In addition, all the reports and literature consulted have indicated that

the steam turbine is mechanically uncoupled from the generator when

operating as a synchronous condenser.


23/60

Q: Is there any clutch available for decoupling the machine from the prime

mover?

A:There is a special type of clutch available commercially called a synchro-

self-shifting clutch (SSS clutch). The clutch is connected between thegenerator and the prime mover. The clutch is an arrangement of fluid-drive

gears which operate automatically by torque reversals. On starting, the

clutch engages both the prime mover and the generator as soon as torque is

applied. When the generator is synchronised to the system, power is cut off

from the prime mover, the clutch disengages and the prime mover slows

down alone. If required the prime mover can be run up again and at thecorrect speed the clutch will engage both machines. This system has been

used on gas turbine generators up to around 100 MVA. The supplier of this

type of clutch is SSS Gears Limited UK.

Note: There should be some form of bound bearing applied to the generatorrotor following disconnection from the turbine. This is to eliminate any axial

movement of the rotor during operation as a synchronous condenser. Also,

for New Cossipore unit 1, the main oil pump is at the governor end,

therefore as the main turbine would be disconnected the auxiliary oil pump

must be in operation during run up and operation of the synchronous

condenser.


24/60

Q: If LP is removed permanently from generator rotor coupling,

can the DC exciter be used as motor and does it have suffcient

drive to run the generator rotor?

A: It is possible for a dc exciter to be used as a motor to run a

generator to full speed no load, however, it is generally the case

that the exciter is designed to take this extra duty. Also, there

requires to be an adequate dc supply available. From the

design files for New Cossipore units 1 and 2 the mechanicallosses (windage and friction) are quoted as 286 kW, the design

rating of the dc exciter is quoted as 225 kW with an output of 90

kW for CMR operation. Although the power required to

overcome the mechanical losses is greater than the rating it may

be possible for the exciter to carry out this duty as it is only

required to run the condenser up to speed, the mechanical

losses will be taken from the generating system once

synchronised.


25/60

Q: If using the DC exciter as a motor is a feasible proposition, then

can the quill shaft also take the torque required to turn thegenerator rotor up to full speed?

A: Another consideration is whether the torsion rod drive will take

the load from the condenser rotor when driven from the dc exciter.

A quick calculation as to the increase in torque applied to the

torsion rod drive when driving the condenser from the dc exciter (as

opposed to driving the dc exciter from the generator) shows an

increase in torque by a factor of approximately 3.6 times. At steady

state conditions, ie, 3000 revs / min, the increased shear stress in

the torsion rod is within the ultimate tensile strength of the material,

however, this does not take account of the initial starting torquerequired to turn the shafts from zero speed. How the application of

current to the dc exciter during starting is carried out is thus

important and should be considered.


26/60

Some precautions which are necessary when

generators are used as synchronous

condensers

1. It must be ensured that in cases where the generator is uncoupled from

the prime mover the lubrication system is still effective.

2. When the rotor is uncoupled it should have no axial play.

3. The synchronous condenser will require protection against over-speeding

and loss of voltage.

4. Overheating is possible when the machine is excited before the rotor is

up to speed, care should be taken to avoid damage to the rotor windings.

5. With small generators coarse synchronising is unavoidable, care must be

taken to choose the most favourable moment to close the synchronising

circuit breaker.


27/60

Mr. Lishman has another proposal for starting

mechanism as commented below

“One area which has not been discussed so far is the use ofanother generator to run up the synchronous condenser to

speed. In this configuration the generator and condenser

armature windings are connected together when both are at

rest or on turning gear via their respective generator

transformers and an isolated route through the station switch

yard. The field circuit breakers of both units are initially

open. The generator and condenser are synchronised at

turning gear speed and run up throughout the speed range as

a synchronous pair. This has been the practice of somecross-compound machines and at least one cross compound

set has been run up, with both generators uncoupled from

their turbines, using a third generator driven by an induction

motor, with all three generators synchronised at turning gear

speed.”


28/60

Some information downloaded from internet and E-mail

correspondence

From Tata Power site

In 1991 Tata Electric Company proposed utilisation of generators of unit-1, 2 &

3 as electrically driven synchronous condensers for P.F. improvement.

From BHEL EDN, Bangalore Site (which supports the above information)

In this page, some landmarks of important achievements in power plant

automation has been listed. One of them is as below

GTO Thyristor controls for starting of 67 MW Synchronous Condenser at TEC-

Trombay Plant, India.

http://www.bheledn.com/acheivments2.htm


29/60

On enquiry from Jojobera power station of Tata Electric the

following information has been received.

•One unit of capacity 62 MW was converted into a synchronouscondenser in the year 1992-93, having capacity of 42/45 MVAR.

•It ran for less than a year before the project was finally

declared failure and shutdown.

•Problems faced were aging, increased maintenance cost.

•Expertise for this project was taken from Tata Consulting

engineers and Tata Power’s own project group.

•Presently no such unit exists in Trombay Power station.


30/60


31/60

IEEE Power Engineering SocietyChicago Chapter 1998-1999

Conversion of Two Zion 1220 Mva Generators to Synchronous Condenser Operation

Wednesday, February 10, 1999

Raymond F. Cameron and Thomas W. Kay

Commonwealth Edison Company

About the Topic

During the Spring of 1998, Commonwealth Edison Company successfully modified two retired 1220

Mva nuclear generators for operation as synchronous condensers. This presentation will discuss the

planning studies which identified the need for the synchronous condenser, alternative starting

mechanisms considered, and operational issues and experience with the synchronous condenser.

The justification for the synchronous condenser was demonstrated by planning studies which

showed the critical need for voltage support after the Zion generators were retired. The synchronous

condensers enabled ComEd to maintain voltage stability margins to the same level as before thegenerators were retired.

During the design stage, one of the biggest challenges in the conversion to synchronous condenser

was designing the starting mechanism. Several alternatives were investigated, including utilization of

a starting motor to accelerate the generators to synchronous speed, and utilization of a variable

frequency drive to accelerate the generator from a standstill.

The first synchronous condenser was synchronized ahead of schedule on May 25, 1998. The

second unit was synchronized on June 2, 1998. The synchronous condensers proved to be a very

valuable asset during operation during the summer of 1998. Operation of the synchronous

condensers enabled ComEd to maintain adequate voltage stability margins throughout the summer.

http://www.ece.iit.edu/~flueck/chicago_pes/1998/anb0210.html


32/60

Correspondence with BHEL, Hyderabad

From Mr. STH Rizvi, GM/PED, R&D Engg

Dear Sir,

Your request letter in this forwarded mail is seen and dicussed with our design

engineers, concerned and the following are our comments:

Generator can be in principle operated as synchronous Condenser to improve Power

factor in the system. But if Generator is to be operated as Synchronous Condenser, a starting

motor with a suitable decoupling device is required to bring generator to synchronous speed. At

present BHEL does not have any such equipment (motor with decoupling device) nor the required

experience associated with this.

However you can visit, if desired so, TNEB Basin Bridge GT Power Plant where BHEL

(HYD) has supplied Generator to operate as generator normally and as synchronous condenser

occasionally.

Further we do not have any knowledge or necessary information on GTO thyristor

controls being supplied by BHEL EDn, Bangalore for 67 MW Synchonous Condenser at TEC as

mentioned in your letter. You may further probe in this matter with our Bangalore unit directly.

Lastly, we do not have information whether anybody in India is taking up jobs of

converting old generators to synchronous condensers.

Trust, we may be of help to you in some other occasion.

Regards.


33/60

Path forward to execution


34/60

Phase-1:

(On immediate basis)

•To prove the rotor withstanding capacity, the team feels to operate

the machine as a generator at a very low active power (to the tune of

4 – 5 MW) and maximum lagging MVAR (to the tune of 26 MVAR)

and P.F.=0.2

•To accomplish this, the following are required

-Generator rotor temperature detection system by VI method

already exists

-Generator Low Forward Power protection to be removed – does not

exist at all

-Generator Reverse Power protection to be incorporated –

Requisition made, order being processed


35/60

Phase-2:(Operation as pure synchronous condenser)

•In this phase, conversion to synchronous condenser is being thought of as

long as steam generation is available and active power from NCGS is

required.

•In this proposition one machine will be decoupled from LP coupling.

•Modification for the lubrication of the synchronous condenser with AOP is

required.

•The stator terminals of two machines are connected together.

•The field breakers of both the machines will be made on when both are at

turning gear speed.•One machine will be started as a generator with steam input which

eventually will speed up the second machine synchronously till the rated

speed is achieved.

•Finally the synchronous pair will be synchronised to the 33 KV Bus Bar.

~ ~Synchronous Condenser Synchronous Generator

Synchronising Circuit Breaker

33 KV Bus Bar


36/60

Phase-3:

(When NCGS retires fully and there is no active

demand & steam generation)

•In this phase, NCGS will be considered as pure synchronous condenserstation.

• The exciter will be used as prime mover.

•The electrical supply to the exciter will be provided from a motor generator

set. One such motor generator set exists at Mulajor Generating Station.

• A separate excitation system will be required for the excitation of the

synchronous condenser


37/60

SEEG

M

33 KV Bus Bar

Synchronising Circuit Breaker

Synchronous

Condenser

3 phase AC supply

Induction Motor

DC Generator

JOP Supply

Turning Gear

Arrangement

Lube Supply

From AOP

Existing Exciter

To be used as

DC Motor

Schematic of phase-3

Extra Thrust

Bearing Arrangement


38/60

Once the task force gets the

direction towards the

execution of the three phases,the team will go in for detailed

engineering with the help of a

competent party.


39/60

CONVERSION OF 30 MW

SYNCHRONOUS GENERATOR

TO SYNCHRONOUS

CONDENSER

A PRESENTATION BY VAR ENHANCEMENT TASK FOCE


40/60

RATING OF THE 30 MW GENERATOR

• MW : 30 MW

• MVA : 35.3 MVA

• VOLTS : 33 KV

• STATOR CURRENT : 618 A

• P.F. : 0.85

• RPM : 3000

• EXCITATION VOLTAGE : 300 V

• ROTOR CURRENT : 260 A

O ti f th U it # 1


41/60

Operation of the Unit # 1

Synchronous Generator at low active and high

reactive:To prove the rotor withstanding capacity, the team felt to operate the

machine as a generator at a very low active power (to the tune of 4 –

5 MW) and maximum lagging MVAR (to the tune of 26 MVAR) and

P.F.=0.2

•To accomplish this, the following additional protections are

incorporated

-Generator rotor temperature detection system by VI method

has been calibrated

-Generator Reverse Power protection relay has been procured

and installed-Generator over voltage relay has been procured and installed

-A new calibrated VAR meter has been procured and installed

-Both the air coolers are cleaned


42/60

Results of the test carried out on

24th November, 2006 are shown in

the next slide


43/60

T/A-1 READINGS FOR LOW ACTIVE POWER & HIGH REACTIVE POWER

TEST ------- ON 24.11.06 L=LIMIT

Sl

.

N

o

Start

Time

Pilot

Excitor

output

voltage

Pilot

excitor

output

crt (1-5)

A

Main

excitor

field

voltage

(7-8) V

Gen.

Field

(rotor)

voltage

V

Gen.

Field

(rotor)

current

(L-260 )

A

Stat

or

volta

ge

KV

Deriv

ed

Powe

r

facto

r

Activ

e

power

MW

Rea

ctiv

e

pow

er

MVA

R

Stator

current

(L-550

A)

Rotor

temp

(L-

190 O

F) =

88 o C

Air Air

cooler

temp I/L

(L- 140 O F)

Air

Air

cool

er

tem

p

O/L

(L-

108

O F)

Cond

Temp

opp ex

duct

(L- 198O F)

Back of

core

temp (L-

198 O F)

End

Time

1 10-10 13 6.3 10.32 118 119 34.2 0.781 5 4 100 34 97 87 107.1 106.7

2 10-20 15 7 11.82 138 139 34 0.53 5 8 135 43 101 88 113.3 116.1 10-30

3 10-35 18 8 13.82 162 162 34 0.385 5 12 235 50 102 88 115.2 123.2 10-50

4 10-50 19 8.6 14.99 184 181 33.9 0.298 5 16 295 56 105 89 120 130.1 11-15

5 11-15 22 9.8 17.53 215 210 33.8 0.242 5 20 380 66 108 90 125.7 136.7 11-45

6 11-45 25 10.6 19.3 240 230 33.8 0.204 5 24 405 82 113 92 136 148 12-40

Frequency = 49.45 HZ Bus voltage = 32.4 KV


44/60

A

Gen. Field Ammeter Shunt

Field Switch

Gen. Field

Voltmeter

T/ARotor

Field

M Ex

Ex Field

Ammeter

MainRheostat

M

ai

n

Neg

Fi

el

dP.

Ex

S

h.

Fiel

d

Fi

el

d

Vo

lt

m

eter

42

68

7513

T/A FIELD EXCITATION SYSTEM

Disc

Res

Main

Ex

Field

Dis

Sw

V

V

Rotor

Temp

Shunt


45/60

Results of the test carried out on

12th December, 2006 are shown in

the next slide

T/A-1 READINGS FOR LOW ACTIVE POWER & HIGH REACTIVE POWER TEST -------

ON 12-12-2006


46/60

Freq

= 49.15 Hz Bus Voltage = 33 KV T/A-1 synchronised at 9-40 AM

Sl.

No

Start

Time

Pil

ot

Ex

cit

or

vo

lta

ge

V

Pilo

t

exci

tor

out

put

ct

A

Main

excito

r field

voltag

e

(7-8)

V

Gen.

Field

(rotor)

voltage

V

Gen.

Field

(rotor)

current

A

Stato

r

volta

ge

KV

Powe

r

factor

Ac

tiv

e

po

w

er

M

W

Reactive

power

MVAR

(from

SCADA)

Reac

tive

powe

r

MVA

R

(from

analo

g

meter

)

Stator

curre

nt

(L-

550

A)

Rotor

temp

(L- 84

O C)

Air Air

cooler

temp

I/L

(L- 140

O F)

Air Air

cooler

temp

O/L

(L-

108 O

F)

Cond

Temp

opp

ex

duct

(L-

198 O

F)

Back

of

core

temp

(L-

198 O

F)

End

Time

1 9-50 15 6.9 140 142 33.2 0.96 10 5 5 190 48 93 80 105.5 108.6 10-15

2 10-15 16 7.5 12.6 149 149 33 0.55 5 10 10 195 54 96 81 110 118.2 10-30

3 10-30 19 8.5 15.2 180 179 32.4 0.32 5 14 14 270 64 97 81 113.3 125.3 11-00

4 11-00 22 9.6 16.7 220 210 32.3 0.26 5 20 20 360 72 99 82 118.2 130.9 11-30

5 11-30 25

10.

9 19.3 245 235 32 0.21 5 25 25 455 82 97 86 125.8 138.6 13-00

6 13-00 27

11.

5 21.05 258 235 32.6 0.1 3 25 25 450 84 93 87 124.8 140 14-00

7 14-00 3 25 25 84 93 88 126.9 143.8 15-00


47/60

SINCE IT IS PROVEN THAT THE MACHINE CAN GENERATE 25

MVAR WITH ALL THE RELEVANT PARAMETERS WITHIN LIMIT,

THE NEXT CHALLENGE IS TO SPEED UP THE MACHINE TO 3000

RPM


48/60

• To accomplish this, the team decided touse the main exciter as DC Motor to turn

the generator rotor.• The generator will remain decoupled

from the LP stage of the turbine

• The Lub oil pump will be in service• JOP will be in service

• As an extra precaution a gravity feed

tank for generator bearing oil will beinstalled

R i f h i i k


49/60

Requirements for the main exciter to work as aDC Motor

• The armature of the main exciter will be fed

with the 90 KW transformer rectifier broughtfrom MGS

• The pilot exciter will be electricallydisconnected from the main exciter shunt field.

• It is observed experimentally that the directoutput voltage of the pilot exciter at 3000 rpmis approximately 100 v dc and fixed in nature.

• Since the pilot exciter voltage will not be available,

hence it is decided to make a separate powersupply tailored to our requirement to feed theshunt of the main exciter


50/60

T/A-1 rpm vs Pilot Gen. DC voltage

0

20

4060

80

100

120

0 1000 2000 3000 4000

rpm

P i l o t G e n

D C V

o l ( V )

DC pilot volt (V)


51/60

• Input voltage: 230 V AC

• Output voltage: 100 V DC• Output current capacity: 20 A

• A minimum current sensing device

• In the event of the shunt current going below a

minimum preset value the armature contactor willdrop out

• In the event of armature contactor dropping out, theshunt current will be removed

• The shunt field power supply will be interlocked to

the lube-oil pressure switch

• The schematic of the power supply unit is shown inthe next slide

The features of the external DC Power supply unit


52/60


53/60

T/A

Rotor

Field

A

Gen.Field

Ammeter

ShuntField

Switch

Gen.

Field

Volt

mete

r

M Ex

Main

Rheostat

Mai

n

N

eg

Fi

el

d

Fi

el

d

Volt

m

et

er

42

68

7513

T/A FIELD EXCITATION

SYSTEM WITH

EXTERNAL POWER

SUPPLY UNIT

Di

sc

.R

es

Mai

n

Ex

Fiel

dV

V90 KW

Tr.

Rectifier

Armature

Supply

Ext

100 V

Power

Supply

Unit P. Ex

Sh.

Field

Rotor

Temp

Shunt


54/60

•90 KW oil cooled transformer rectifier brought from MGS.

•Output DC current capacity: 300 A

•Output DC voltage (with step less control): 0-300 Vdc


55/60

New 100 V DC power supply to feed the main exciter shunt

field externally


56/60

•DC power contactor of the 90 KW transformer rectifier being mounted

on a separate obsolete panel

•A load test has been carried out for the transformer rectifier with

heater load


57/60

•Front view of the 100 V DC power supply. When the shut current is below

set value, the red lamp will glow and drop out the DC contactor of the

armature supply.

•When the shut current is more than the set value, the green lamp will glow

and enable the armature DC contactor to pick up


58/60

The 100 V DC power supply is being tested for set value


59/60

STEPS TO BE FOLLOWED FOR MOTORING

THE ROTOR WITH MAIN EXCITER

• OCB ISOLATED/ VT DISCONNECTED / UNIT TRANSFORMER ISOLATED & RACKED OUT

• TURBINE DECOUPLED.• AOP IS PUT IN SERVICE AND LUBRCATING OIL PRESSURE O.K.

• JACKING OIL Pp. RUNNING JUST BEFORE THE OPERATION.

• DOUBLE AAF IS PUT IN SERVICE.

• A NEWLY INSTALLED ELECTRONIC RPM METER IS PUT IN SERVICE.

• 300A CFS IS KEPT ON FOR 90 KW RECTIFIER TRANSFORMER.

• A.C. 220 V SOURCE IS AVAILABLE FROM REMOTE.

• EXCITATION RHEOSTAT AT SWITCHBOARD IS KEPT AT ITS MINIMUM PSITION.

• ATA IS RESET TO ENABLE THE AAFS TO RUN.• RECTIFIER TRANSFORMER AT MIN TAP.

• PSU UNIT PUT ON BY PRESSING THE BYPASS SWITCH AND THE POWER CONTACTOR OF MAIN

EXCITER ARMATURE SUPPLY IS MADE ON.

• BYPASS SWITCH IS RELEASED ONLY AFTER THE POWER CONTACTOR OF THE MAIN EXCITER

POWER CONTACTOR IS MADE ON.

• THE RHEOSTAT POSITION IN THE SWITCH BOARD IS SLOWLY INCREASEDUNTILL THE PSU REGISTRS

10 AMPERES.

• IN THE PROCESS IT IS TO BE NOTED THAT THE MINIMUM SET CURRENT VALUE IS REACHED.• AAT THIS STAGE IT IS EXPECTED THAT THE FULL EXCITATION FLUX IS ESTABLISHED.

• THE ARMATURE SUPPLY VOLTAGE IS THEN SLOWLY INCREASED UNTILL THE GENERATOR ROTOR

STARTS ROTATING.

• CONSIDERING THE RATED VOLTAGE AND THE CAPACITY OF THE MAIN EXCITER ARE 300 VOLTS AND

90 KW RESPECTIVELY, IT IS TO BE NOTED THAT IN NO CICUMSTANCES THE MAIN RXCITER OUTPUT

VOLTAGE AND CURRENT EXCEEDS 300 V AND 300 A.


60/60

Presentation (Synch Condenser)

Documents

Transcript of Presentation (Synch Condenser)