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Typical Limiting Values of Sub Station Electrical Equipments.

1. Transformer / Reactor:

Sr. No. Equipment / test data ermissible limits Reference

A)

Transformer oil

a) BDV

-At the time of first charging 60 kV (Gap – 2. mm) – !inim"m #$ – %&66

-D"ring '! 0 kV (Gap – 2. mm) – !inim"m #$ – %&6

 *) !oist"re content #$ – %&6&

-At the time of first charging % ++! (!a,.) #$ – %&6

-D"ring '! 2 ++! (!a,.) #$ – %&0

c) esisti/it at 0 1egree 0.%-%0%2 'hm-! (!in.) #$ – %&%

1) Aci1it 0.2 mg 3'45gm (!a,.) #$ – %&2

e) #T at 2 1egree 0.0%& 75! (!in.) #$ – %&8

f) Tan 1elta at 0 1egree 0.20 (!a,.) #$ – %&9

g) lash point %26 Deg. (!in.) #$ – %&

B)Vi*ration le/el for reactors 200 !icrons (+eak to +eak) #$ – %&6

  60 !icrons (A/erage) #$ – %&

) Tan 1elta for *"shing at 20 Deg. 0.00: #; – %8

D) apacitance for *"shing < = /ariation #; – %8&

;) # /al"e for >in1ing%000 !-'hm B .05%0.0 kV

!egger 

#; – %8

)Tan 1elta for >in1ings at 20 Deg.

0.00: #;;;5.%2.0.%&0

G)ontact resistance of *"shing

terminal connectors

%0 !. 'hm 5 onnector 

 7G.?3 ecommen1atio

4) T"rret 7e"tral T ratio errors 8 #$ – 20

 !. "ircuit #rea$ers

Sr. No. Equipment / test data ermissible limits Reference

A) De> point of $6 gasDe> point /al"es as per Anne,"re

 – ##

B) De> point of operating air -9 Deg. at AT!. +ress"re

) B 'perating timings 900 kV 2203V

a) losing time (!a,.) %0 !$ 200!$

 *) Trip time (!a,.) 2 !$ 8!$

c) lose5trip time@ +ole

1iscrepanc

 – +hase to +hase (!a,.) 8.88 !$ 8.88!$

-Break to *reak (!a,.) of same 2. !$ 2.!$

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 phase

D)

+# time

B4; make%2-%6 !$

!an"fact"rers

ecommen1ations

 

ABB make&-%2 !$

!an"fact"rers

ecommen1ations

 7G; make&-%2 !$

!an"fact"rers

ecommen1ations

!G make&-%2 !$

!an"fact"rers

ecommen1ations

T;3 make&-%2 !$

!an"fact"rers

ecommen1ations

ABB make (4VD) &-%2 !$

!an"fact"rers

ecommen1ations

;)

+# opening time prior to opening

of main contacts (ABB@ G@

 7G; make Bs) !$ (!in.) at rate1 press"re

!an"fact"rers

ecommen1ations

)

+ir an1 main contacts o/erlap time

B4;@ !G@ ABB (importe1)

make BsC 6 !$ (!in.) at rate1 press"re

!an"fact"rers

ecommen1ations

G) Tan 1elta of gra1ing capacitors 0.00 at 20 Deg.

4) apacitance of gra1ing capacitorsithin < %0= 5 -= of the rate1

/al"e #; 8

#) ontact resistance of B %0 !. 'hm

E)ontact resistance of B terminal

connector %0 !. 'hm per connector 7G@ ?3 recommen1atio

3)

# /al"eF

%. +hase – earth%000 ! 'hm (!in.) * .0 5 %0.0

kV !egger

2. Across open contacts%000 ! 'hm (!in.) * .05%0.0 kV

!egger

8. ontrol ca*les0 ! 'hm (!in.) * 0. kV

!egger

)

+ress"re s>itch settings

-$6 gas press"re s>itches ithin < 0.% Bar of set /al"e

-'perating air pr. $>itches ithin < 0.% Bar of set /al"e

-'perating oil pr. $>itches ithin < 0.% Bar of set /al"e

!)

BDV of oil "se1 for !'B

-At the time of filling 90 kV at 2. mm Gap (!in.) !fgs. ecommen1ation

-D"ring '! 20 kV at 2. mm Gap. (!in.) !fgs. ecommen1ation

 %. "urrent Transformer

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Sr. No. Equipment / test data ermissible limits Reference

A)

# /al"e

%. +rimar – earth%000 ! – 'hm (!in.) * .05%0.0

kV !egger

2. $econ1ar – earth 0 ! – 'hm (!in.) * 0. kV!egger

8. ontrol ca*les0 !-'hm (!in.) * 0. kV

!egger

B) Tan 1elta /al"e 0.00: at 20 Deg.

) Terminal onnector  %0 !-'hm per connector 

 7G@ ?3

ecommen1ations

D) T ratio errors < 8= -+rotection cores #$ – 20

D) T ratio errors < %= -!etering cores #$ – 206

 &. "apaciti'e Voltage

Sr. No. Equipment / test data ermissible limits Reference

A) Tan Delta 0.00: at 20 Deg.

B) apacitanceithin <%0=5-= of the rate1

/al"e #; – 8&

ontact resistance of terminal

connector %0 !-'hm per connector  

 7G@ ?3

ecommen1ations

D)

# Val"e # Val"e

%. +rimar – earth %000 ! – 'hm (!in.) * .05%0.0kV !egger

2. $econ1ar – earth0 ! – 'hm (!in.) * 0. kV

!egger

8. ontrol ca*les0 !-'hm (!in.) * 0. kV

!egger

;)

;!? tank oil parameters ;!? tank oil parameters

a) BDV (!in.) 80 kV (Gap. –2. mm) #$ – %&66

 *) !oist"re content (!a,.) 8 ppm -1o-

c) esisti/it at 0 Deg. 0.% – %0%2 'hm. – ! -1o-

1) Aci1it 0. mg k'4 5gm (!a,.) -1o-

e) #T at 2 Deg. 0.0%& 75! (!in.) -1o-

f) Tan 1elta at 0 Deg. %.0 !a,. -1o-

g) lash point %2 Deg. (!in.) -1o-

) VT /oltage ratio errors < = protection cores #;;;58.%.%0

) VT /oltage ratio errors < 0.= metering cores #; %&6

 (. )solators

Sr. No. Equipment / test data ermissible limits Reference

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A) ontact resistance 800 !-'hm. (!a,.)

B)ontact resistance of terminal

connector %0 ! – 'hm per connector  

 7G@ ?3

ecommen1ations

)

# /al"e

%. +hase – earth %000 ! – 'hm (!in.) * .05%0.0kV !egger 

 7G@ ?3ecommen1ations

2. Across open contacts%000 ! – 'hm (!in.) * .05%0.0

kV !egger 

 7G@ ?3

ecommen1ations

8. ontrol ca*les0 !-'hm (!in.) * 0. kV

!egger

*. Surge +rrester

Sr. No. Equipment / test data ermissible limits Reference

A) eakage c"rrent 00 !-Amp. (esisti/e) 4itachi@ Eapan ecom.

B) # /al"e %000 !-'hm. (!in.) 4itachi@ Eapan ecom.

 ,. -iscellaneous

Sr. No. Equipment / test data ermissible limits Reference

A) $tation earth resistance %.0 'hm (!a,.)

B)

Thermo /ision scanning

Temp. "p to % Deg. (a*o/e

am*ient) 7ormalTemp. a*o/e %-0 Deg. (a*o/e

am*ient) Alert

Temp. a*o/e 0 Deg. (a*o/e

am*ient) To *e imme1iatel atten1e1

)Terminal connectors – ontact

resistance %0 !-'hm per connector  

4G@ ?3

ecommen1ations

D)

# /al"es

%. All electrical motors0 !-'hm (!in.) * 0. kV

!egger

2. ontrol ca*les0 !-'hm (!in) * 0. kV!egger

8. t. Transformers %00 !.-'hm (!in.) * !egger

9. t. $>itchgears%00 ! – 'hm (!in.) * 0. kV

!egger

. #atteries

Sr. No. Equipment / test data ermissible limits Reference

A) Terminal connector resistance %0 ! – 'hm < 20= A7$#5#;;; – 90 %&B) $pecific gra/it %200 < G!5 at 2 Deg.

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 Temperature "orrection actor for Tan 0elta -easurement

 

Sr. No. il temperature 0eg. " "orrection factor234

% %0 0.&

 2 % 0.

 8 20 %.0

 9 2 %.%2

  80 %.2

 6 8 %.90

  90 %.

 & 9 %.

  0 %.

 %0 2.%&

 %% 60 2.92

 %2 6 2.0

 %8 0 8.00

 

#f Tan Delta of *"shing5>in1ing5VT5T is meas"re1 at oil temperat"re T Deg. . Then Tan

Delta at 20 Deg. shall *e as gi/en *elo>F

Tan 0elta at !5 0eg. " 6 Tan 0elta at Temp T 0eg. " / actor 3.

0e7 oint Limits for S* 8as in E9V "ircuit #rea$ers

Sr.

No

Make of C.B 0e7 point at rated

r. 0eg. "

"orresponding de7 point

at +tmosperic .r. Remar$s

1 BHEL -% -86 At the time of commissioning

 - -2 D"ring '!

 - -2 ritical

2 M&G  – -8 At the time of commissioning

  -82 D"ring '!

3 CGL  -% -8 At the time of commissioning

 -%0 -8% D"ring '!

4 ABB  -% -8 At the time of commissioning

 - -26 D"ring '!

5 NGEF  -% -86 At the time of commissioning

 - -2 D"ring '!

 Note: Dew point of SF6 ga !a"ie wit# p"e$"e at w#i%# ea$"eent i%a""ie' o$t( So it i to )e en$"e' t#at if ea$"eent i 'one at p"e$"e

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ot#e" t#an atop#e"i% p"e$"e* it nee' to )e %on!e"te' to t#eatop#e"i% p"e$"e(