4. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code :SOP/MV-6.6KV/Rev:00
1.1. INTRODUCTION:Systematic Standard Operation
of the system has become most important for
ensuringsafe operation of Switchgear results in
least possible down time, extension of the
service life of the equipment,safety,reductionof
interruptions.
1.2. SCOPE:The policies defined in this document
cover a wide range of subjects about safe
operation of HIGH VOLTAGE 6.6 KV GIS SWITCH
BOARDwith compliance of ELECTRICAL SAFETY
RULES.
1.3. PURPOSE:These ELECTRICAL SAFETY
OPERATIONAL PROCEDURES are issued by the
NMDC Electrical Department to supplement the
ELECTRICAL SAFETY RULES and define policies
that assist in their implementation.
1.4.DEFENITION & ABBREVIATION:
AIS- Air Insulated Switchgear
A-I-M - Auto Independent Manual Switch
TSS - Trip Selection Switch
Synch – PT Voltage synchronisation
L/R- Local /Remote.
SCADA -Supervisory Control and Data
Acquisition.
IC-INCOMER
BC-BUS COUPLER
OG-OUTGOING
HV- HIGH VOLTAGE
LV-LOW VOLTAGE
Another INCOMER- The incomer on which
operation is not being performed.
Feeder & panel are interchangeably used.
1.5.Basic Rules
1.5.1. Before carrying out any SWITCHING operations
on a unitof HV or LV switchgear,check if it has a
'Plant Restriction' marker label fixed and check
its general condition by a visual inspection.
1.5.2. Do not trust your memory; consult your
SWITCHING PROGRAMME or written
instructions before carrying out any operation.
1.5.3. When instructed to carry out SWITCHING by
telephone or walkie-talkie, write down the
instruction and read it back to the person who
has given it to you.
1.5.4. Make sure you understand how the apparatus
you are going to operate works.
1.5.5. If in doubt, ask for assistance to your in-charge
or check if information that would help is
available.
1.5.6. Do not do experiment with LIVE APPARATUS.
1.5.7. Checkthe existingpositionof the switch you are
intend to operate. Is it in the position you
expected (i.e., closed, open, and EARTHED) If
not, inform the Shift In Charge.
1.5.8. Checkthe title (name) of anycircuittwice before
operating. If the title is not the same as your
SWITCHING PROGRAMME or instruction, inform
to concernedshiftIn-charge anddo not proceed
further, until proper confirmation of the title.
1.5.9. Check the visual indications, ammeters,
voltmeters, etc for verifications.
1.5.10. All protection relays’ indications shall be
recorded in the log book before resetting any
relay.
1.5.11. Rememberto pause and think before you act in
an operational substation or situation. All your
actionsshouldbe deliberate and not impulsive.
1.5.12. Whenleavingasubstationmake sure everything
is correctly locked and the substation door
secure.
1.6.Safety precautions before starting the job:
1.6.1. Inform the concerned downstream in-charges
before executing any operation.
1.6.2. Carry walkie-talkie to the work spot.
1.6.3. Wear Personal Protective Equipment such as
Safety shoes, Safety Helmet, Dust mask, Ear
plug, goggles and HT Hand Gloves etc. as per
requirement.
1.6.4. Ensure sufficient lighting at work place.
1.6.5. Ensure proper means of escape.
1.6.6. Ensure the availability of Fire Extinguisher.
5. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
1.6.7. Ensure the availability of First Aid Kit.
1.6.8. Ensure FDA system is working.
1.6.9. Ensure propermeansof escape is available near
work site.
1.6.10. Tool Box Talk to be conducted.
1.6.11. In case of Electrical shock instantly report to
control room & safety officer to arrange for first
aid as required
1.7. Requirement before starting the job:
1.7.1. Valid work permit.
1.7.2. LOTO
1.7.3. Follow all the Safety norms.
1.7.4. Toolbox kit
1.7.5. HIRA & JSA. (ReferHIRA Doc No .1)
1.7.6. Manpower (At least 2, Engineer presence is
must).
1.7.7. Breaker Spring Charge handle
1.7.8. 33 kV Panel key
1.7.9. Ladder or stool
1.7.10. Multi-meter
1.7.11. logbook
1.7.12. Other required accessories
1.8.Roles & Responsibilities:
Primary Responsibility: Field operator, Desk
engineer in respective LBDS (PPDS).
Secondary Responsibility: Shift In charge.
Overall responsibility: Operation In-charge.
Controlling & reviewing: HOD /O&M.
A. STEPS TO BE FOLLOWED TO SWITCH – ON 6.6KV
INCOMER FEEDER:
i) Condition before switching ON IF1 - IF2 and BC
are in On condition, and also outgoing feeders of
both sections are in ON condition.
ii) Switching ON IF1 after maintenance of IF1
iii) Switching of IF1 after maintenance of
respective Power Transformer
iv) Switching ON IF1 after bus bar maintenance
V) Switching ON IF1 when IF2 is already ion OFF
condition.
Vi) Swithing on IF1 after tripping on fault
Vii) Switching ON IF1 after intertrip
Viii) Switching ON IF1 when IF2 is ON and BC is OFF.
i) Condition before switching ON IF1:- IF2 and BC are in
On condition and also outgoing feeders of both
sections are in ON condition.
a) Obtain the clearance from shift incharge, CCC
operator and NMDC inc-charge.
b) Inform shift incharge of respective downstream.
c) Check the reasons due to which IF1 kept OFF.
d) Ensure no any persisting faults appearing in
numerical relay.
e) Ensure PTW is returned and isolation tag is
removed, if applicable.
f) Check maintenance report of IF1, if applicable.
g) Ensure cable chamber door is closed properly.
h) If no fault is found and maintenance report is also
OK, we can proceed for charging. For charging
following steps are to be followed.
i) Check line PT voltage in MFM, analogue voltmeter
and numerical relay.
j) Ensure the LINE VOLTAGE should be greater than
95% of nominal voltage 6.6kV (i.e.PTvoltageshould
not be Less than 6.27 KV.
k) Check position of CB in the IF1, whether the
breaker is in TEST position or in SERVICE position.
l) If CB is in TEST position, Check all the binary
input(BI) status in numerical relay.
m) FollowingBinaryinputs status should be in HIGH(1)
condition.
I. L1-86 RESET
6. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
II. L2-MCB3 HEALTHY
III. L3-TRIP CIRCUIT HEALTHY
IV. L5-CB OPEN
V. L6-CB SPRING CHARGE
VI. L7-CB IN TEST
VII. L18-LOCAL/REMOTE IN LOCAL
VIII. L19-IF2 CB CLOSE
IX. L21-BC CB CLOSED
n) If any BI as above mentioned is not getting High (1)
then inform to Shift incharge and if above BI status
is OK then following steps should be followed.
o) IF CB in Test Position, Following Indication lamp
should glow.
I. CB OFF - Green
II. Trip Circuit Healthy- White
III. Spring Charged- Blue
IV. CB in Test Position- White
V. Lock out Relay Healthy- White
p) Ensure CB chamber door is closed.
q) Checkthe electrical operationof CB in test position
in LOCAL & REMOTE mode. Follow the steps
described below from
r) For LOCAL operation, keep the L/R selector switch
in LOCAL mode.
s) Close the CB from TNC switch and check BI input
statusin numerical relay,indicationlampstatusand
52X flag operation.
t) Ensure CB spring got charged after closing the CB
and check status of SPRING CHARGE Indication
lamp.
u) If SPRING CHARGE INDICATION LAMP glows,
proceed for charging, otherwise inform to shift
incharge to rectify the problem.
v) Switch OFF the CB of IF1 using TNC switch.
w) Keep the L/R switch in REMOTE mode to check the
CB operation remotely.
x) Coordinate with CCC operator to check the
operation of CB of IF1 in TEST position in REMOTE
mode.
y) CCC operator will check the healthiness status of
IF1 in HMI before operation.
z) CCC operatorwill check the switching operation by
giving closing and tripping command from SCADA.
aa) If CB operation is found OK in Local and Remote
then proceed and Following instruction should be
followed.
bb) Informshiftincharge and CCC operator then rack in
CB into service position.
cc) Afterrack-inEnsure Service positionindicationlamp
glows.
dd) Ensure position of CB is in service and matching
with service position mark given in CB cubicle, use
torch and check through glass view which is given
in CB chamber door.
ee) If CB isnot rackedincompletelyorstuckduringrack
in then rack out CB and inform to shift incharge.
ff) If CB isproperlyrackedinthenproceedfor charging
and following steps should be followed.
gg) Keep Auto/Manual switch in Manual.
7. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
hh) Ensure which feeder is to be
ii) Select Trip selector switch in Bus coupler.
jj) If CB is in service position, Check all the binary
input(BI) status in numerical relay.
kk) FollowingBinaryinputs status should be in HIGH(1)
condition.
I. L1-86 RESET
II.L2-MCB3 HEALTHY
III. L3- TRIP CIRCUIT HEALTHY
IV. L4-IF1 CB CLOSE
V. L5- CB OPEN
VI. CB
L2-
L5-CB OPEN
L6-CB SPRING CHARGE
L7-CB IN TEST
L18-LOCAL/REMOTE IN LOCAL
L19-IF2 CB CLOSE
L21-BC CB CLOSED
ll)
1. Ensure READY TO CLOSE LED
innumericalrelay(ALSTOMP143 or any) is glowing.
2. Login the SCADA as Operator or skip to step 27,if
SCADA control is not available.
3. Keep L/R selector switch in REMOTE.
4. Execute the Close command from SCADA to close
the Circuit Breaker.
5. KeepL/Rswitchin local mode use “TNC” switch to
close the breaker.
6. If any problem found while closing, rectify the
problem or contact Shift-in-charge.
7. If breakergetsclosed,follow further instructions.
8. Ensure the healthiness of all relays, Trip circuit,
spring charge, all indication lamps & any other
installedequipmentandSCADA HMI afterclosing
the breaker.
mm)
nn)
9. Ensure shutdown permit has been returned.
10. Ensure all the tools & tackles are removed and no
maintenance personnel are not present at the
specific site.
11. Keepthe AIS area clean and free from any
obstacles.
12. Get the clearance fromelectrical EngineerShift-in-
charge & also from down-stream end.
13. Reset numerical relay if tripping record is
persisting.
14. Ensure all the equipment installed in the IC panel
are in healthy condition.
15. Ensure no faultinany of outgoingfeeder/breaker.
16. Ensure proper protection setting is maintained in
the numerical relay.
17. Ensure time of the numerical relayissynchedwith
GPS.
18. Remove the “LOTO” tagsfrom “INCOMER” feeder.
19. Once check the maintenance report,if the breaker
& panel were under breakdown or preventive
maintenance.
20. Isolate & rack-out the corresponding EARTH
TRUCK Breaker, ifit was inserted during the
maintenance in the respective panel.
21. Keep the Earth Truck in assigned location in the
substation.
22. Ensureclosing spring of INCOMER VCB is
discharged and then Rack it in the VCB to test
position.
23. Plug in breaker control socket.
24. Normalize the AC/DC control supply.
25. check the test position indication in the panel.
26. Ensure the healthiness of trip circuit and all the
Auxiliary & Protection relays.
27. Testthe all the breakeroperationin test position.
8. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
28. Rack in the breaker to service position safely and
check the service position indication lamp.
29. Ensure that VCB- closing spring is charged.
30. Incomer can be closed in two modes
22.1. MODE 1: Independent (or) Dead bus mode
In this mode, any two out of three breakers(IC-
1,BC & IC-2) can be switched ON.
Case 1: BC-OFF&OTHER IC - ON
Case 2:BC-OFF &OTHERIC- OFF
22.1.1. There must be no fault on the bus of that
section whose incomer feeder is going to be
switched ONand ensure that Master trip relay
(86) of (IC-1&2 and BC )should be in healthy
condition.
22.1.2. Follow step 23 to 37 to operate the breaker in
INDEPENDENT mode.
22.2. MODE 2: Manual (or) Momentary paralleling
Mode.
22.2.1. BC-ON &OTHERIC–ON
22.2.2. Follow step36 to 44 to operate the breaker in
manual mode.
31. Keep Auto-Independent-Manual switch in
Independent mode.
32. Ensure the LINE VOLTAGE should be greater that
95% of nominal voltage 6.6 kV (i.e. Not Less than
6.27 KV.)
33. Ensure READY TO CLOSE LED in
numericalrelay(ALSTOMP143 or any) is glowing.
34. Login the SCADA as Operator or skip to step 27,if
SCADA control is not available.
35. Keep L/R selector switch in REMOTE.
36. Execute the Close command from SCADA to close
the Circuit Breaker.
37. KeepL/Rswitchin local mode use “TNC” switch to
close the breaker.
38. If any problem found while closing, rectify the
problem or contact Shift-in-charge.
39. If breakergetsclosed,follow further instructions.
40. Ensure the healthiness of all relays, Trip circuit,
spring charge, all indication lamps & any other
installedequipment andSCADA HMI afterclosing
the breaker.
41. Keep Auto- Independent -Manual switch in Auto
mode if BC feeder &its breaker are in healthy
condition and both the incomers are in Switched
ON condition.
42. Logout from SCADA as Operator and Login as
Monitor.
43. After closing the breaker, check & note all the
Electrical parameters in SCADA HMI.
44. Inform to NMDC in-charge after charging the
feeder.
45. Note down the following in logbook:
a) Name of the LBDS.
b) Date& Timeof operation from numerical
relay.
c) Feeder serial no.
d) Details of charged feeder.
e) All the required electrical parameters.
f) Healthiness status of the feeder.
g) Shift-in-charge, Area-in-charge.
h) Name of the requester.
i) Charging code, if generated.
j) CCC operator’s name.
k) Name of the Engineers& technicians who
have performed the job.
46. Keep Auto- Independent -Manual switch in
Manual mode
47. TheTripSelectorSwitch(TSSswitch)istobekeptina
position(either IC-1 or BC or IC-2)which is to be
tripped.
27.1. In case of IC-1 charging, keep the TSS at either
IC-2 or BC which is required to be tripped.
27.2. In case of IC-2 charging, keep the TSS at either
IC-1 or BC which is required to be tripped.
48. Numerical relay (MicomP143 or any) will
checkthesynchronizationbetween respective
IncomerLine voltage&Bus voltage.
49. If two sources are satisfying the
synchronisationcondition,the indication lamp,
assignedforcheck-synch,of Numerical Relaywill
glow.
50. Follow step 24 to 29 to give close command.
51. After closing, two incoming supply will become
parallel throughBC for a moment. “This is called
as Momentary Paralleling”.
52. Based on the selection of TSS position, the
selectedfeeder (Either IC or BC) will get tripped
9. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
after pre-definedtime delay.If it fails to trip
automatically,switch OFF the breaker of the
feeder manuallywhich is selected in TSS.
53. Ensure both the bus sections are charged.
54. Follow steps30to 37 except 33.
B. STEPS TO BE FOLLOWED TO SWITCH-OFF 6.6KV
INCOMER FEEDER:
55. Ensure shutdown permit is taken.
56. Ensure the Feeder no.&Tag Name.
57. Inform all the concerned downstream end users
58. CASE-1: If total Bus is charged through any one
IC&BC.
59. Transfer the load to OTHER IC, if OTHER IC is
healthy,usingMANUALmode operationdescribed
from steps 38 to 46. Also follow the steps from 1
to 22.
60. In this mode, IC will trip automatically.
61. After transferring the load to OTHER IC, rack out
the breaker form service position to test position
if testing is required.
62. If OTHER IC feeder is not healthy, get clearance
from downstream in-charge before taking
shutdown of any of the incomer.
63. Follow instruction from steps 56 to 59 to switch
OFF the IC feeder.
64. Login the SCADA as Operator or skip to step59, if
SCADA control is not available.
65. Keep L/R selector switch in REMOTE.
66. Execute the OPEN command from SCADA to
switch OFF the Circuit Breaker.
67. KeepL/Rswitchin local mode use “TNC” switch to
Switch OFF the breaker.
68. If any problemfoundwhile Switching OFF, rectify
the problem or contact Shift-in-charge.
69. After Switching OFF the breaker, rack out the
breaker from service position to test position.
70. Tag the LOTO in the panel.
71. Check & note all the Electrical parameters in the
feeder &SCADA HMI.
72. Check the bus voltage in SCADA HMI Page &BUS
PT.
73. Log-out SCADA as “Operator” and log in as
“monitor”.
74. Inform the site in-charge/NMDC in-charge about
the operation.
75. Note down the following in logbook:
l) Name of the LBDS.
m) Date& Time of operation from numerical
relay.
n) Feeder serial no.
o) Details of charged feeder.
p) All the required electrical parameters.
q) Healthiness status of the feeder.
r) Shift-in-charge, Area-in-charge.
s) Name of the requester.
t) Charging code, if generated.
u) CCC operator’s name.
v) Name of the Engineers& technicians who
have performed the job.
76. CASE-2: If both Incomer Feeders are in charged
condition & Bus Coupler is in OFF condition.
77. If BC feederishealthy,transferthe complete load
to OTHER IC throughLoad transferscheme before
switching OFF any of the Incomers.
78. To switch OFF any of the Incomers, follow 56 to
65.
79. If BC feederisnothealthy,switchoff anyone IC as
per requirement after getting clearance form
downstream in-charge and follow instruction
from steps 56 to 65 to switch OFF the IC feeder.
80. If complete shutdown is required, get clearance
from downstream and followsteps 56 to 65 to
switch OFF the IC feeder.
81. To switchOFFany of the Incomers,alsofollowthe
general rules.
FOR INCOMING LINE DISCHARGE
82. Ensure that LINE isDead(Line PTvoltage shouldbe
zero) and UPSTREAMBreaker isin Switched “OFF”
condition and LOTO is tagged.
83. Switch of the AC/DC control supply if required.
84. Remove plug socket from the breaker.
85. Rack out the breakerfrom the panel andkeepit in
an assigned location in the substation.
86. Ensure healthiness of Feeder Earth Truck (PT,
contact fingers,Vacuum Interrupter, limit switch,
flexible cables etc.) and rack it in the Incomer
Feeder.
10. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
87. Ensure there is NO buzzer active in Earth truck.
88. Keep the panel door open and close the Feeder
Earth truck by pressing the FEB close push button
in Panel.
89. Close the door and use LOTO in the discharged
panel.
90. Ensure the LOTO tag has full details of the panel
mentioned in the work permit.
91. Record the details as per the list mentioned at
step 66.
C. STEPS TO BE FOLLOWED TO SWITCH-ON 6.6KV BUS
COUPLER:
92. Follow steps 1 to 14 based on the site condition.
93. If BC breaker is kept isolated from the panel,
discharge the closing spring of BUS COUPLER VCB
for safety&thenrackinthe breaker to testposition.
94. Follow steps 15 to21.
95. There must be no fault on the bus and ensure that
Master trip relay(86) of (IC-1, IC-2 and BC )should
be in healthy condition.
96. The Bus-coupler can be closed in any of the three
modes (Mentioned in steps 60,61 & 62).
97. MODE 1 : Independent (or) Dead bus mode
a. IC-1-OFF &IC-2- ON (This case is similarto case 1
mentioned under step 22.1.)
b. IC-1-ON &IC-2 OFF (This case is similarto case 2
mentioned under step 22.1.)
c. Follow steps from 23 to 37 for BC feeder.
98. MODE 2: Manual (or) Momentary paralleling
Mode
90.1. Ensure IC-1 &IC-2 are in ON condition.
90.2. Follow steps from63 to 70 only.
91. MODE 3: Auto Closingmode
91.1. Ensure IC-1&IC-2- are ON and BC is OFF &
service position.
91.2. The BC will getclosedautomaticallyif anyone of
the INCOMER is tripped in under voltage.
91.3. Follow steps71 to76
92. Keep Auto- Independent -Manual switch in Manual
mode
93. TheTripSelectorSwitch(TSSswitch)istobekeptin a
position(IC-1 or IC-2) which is to be tripped.
94. P143 Relaywill checkthesynchronizationbetweenthe
twoBUS VOLTAGES.
95. If two sources are satisfying the synchronization
condition, the indication lamp, assigned for check-
synch, of Numerical Relay will glow.
96. Follow step 24 to 29 to give close command.
97. Afterclosing the BC breaker, two incoming supply
gets paralleled through BC for a moment. “This is
called as Momentary Paralleling”.
98. Based on the position of TSS, the selected feeder
(Either IC1 or IC2) will get tripped
automaticallyaftera pre-definedtime delay, if it
fails to trip switch OFF the breaker which is
selected in TSS.
99. Follow step 30 to 37 except 33.
100. A-I-Mselector switch is to be kept in
“Auto”position.
101. If any one of the INCOMERS get tripped
manually or in UV , the breaker of BC will get
closed automatically and the dead bus will get
instantly charged.
102. Incomer tripping & bus-coupler closing will
happen simultaneously, if there is no
intentionaltime-delay.
103. Check the bus voltage in SCADAHMI Page &BUS
PT.
104. Ensure the healthiness of all relays, Trip circuit,
spring charge, all indication lamps & any other
installed equipment after auto closingof BC
breaker.
105. Record the switching operation in logbook.
106. Informsite in-charge/NMDCin-charge about the
operation.
D. STEPS TO BE FOLLOWED TO SWITCH-OFF 6.6KV
BUSCOUPLER FEEDER:
107. Ensure shutdown permit is Taken.
108. Doubly ensure the Feeder no & Name.
109. Inform all the concerned downstream end users
and get their clearance.
110. Case 1: If any of theIncomers & Bus Coupler are
ON and OTHER IC is OFF but it healthy.
111. If case 1 satisfies, follow the IC Load transfer
procedure, i.e. energise both the buses through
individual IC before switching OFF the BC.
11. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
112. To energise both buses through individual IC
withoutanypowerinterruption,follow stepsfrom
38 to 46.
113. Case 2: If any of the Incomers & Bus Coupler are
ON and OTHER IC is OFF but it not healthy.
114. If case 2 satisfies, follow steps from 86
115. Get clearance from downstream
consumer/consumers.
116. If get clearance, Login the SCADA as Operator, if
not available skip to step 90.
117. Keep L/R selector switch in REMOTE.
118. Execute the OPEN Command to switch OFF the
breaker.
119. Keep L/R switch in local mode use “TNC” switch to
Open the breaker.
120. Checkthe bus voltage in SCADAHMI Page &BUS PT.
121. Follow steps 60 to 66.
E. STEPS TO BE FOLLOWED TO SWITCH -ON 6.6KV
OUT GOING FEEDER:
122. Ensure PTW has been returned if the feeder was
under shutdown for maintenance.
123. Ensure all the tools & tackles are removed and no
maintenance personnel are not present at the
specific site.
124. Once check the maintenance report,if the breaker
& panel were under breakdown or preventive
maintenance.
125. if maintenance activities has not been done,
confirm why the feeder was in OFF condition.
126. Ensure whether downstream consumer has
requested for charging the feeder.
127. Get the clearance fromelectrical EngineerShift-in-
charge & also from down-stream end.
128. Reset numerical relay if tripping record is
persisting.
129. Ensure all the equipment installed in the IC panel
are in healthy condition.
130. Ensure no fault in the breaker.
131. Ensure proper protection setting is maintained in
the numerical relay.
132. Ensure time of the numerical relayissynchedwith
GPS.
133. Keep the AIS area clean and free from any
obstacles.
134. Remove the “LOTO” tags from “respective”
feeder.
135. Isolate & rack-out the corresponding EARTH
TRUCK Breaker, if it was inserted during the
maintenance in the respective panel.
136. Keep the Earth Truck in assigned location in the
substation.
137. Rack out the earth truck and isolate from the
panel.
138. Ensure closing spring of the respective breaker is
discharged and then Rack in the VCB to test
position.
139. Plug in breaker control socket and rack it in the
breaker to service position.
140. Normalize the AC/DC control supply.
141. Ensure healthinessof tripcircuitandall the relays.
142. Ensure that closing spring of the breaker is
charged.
143. Ensure the “BUS” is “LIVE”.
144. If “Bus” is “Dead”, check incomer feeder.
145. Loginthe SCADA as Operatoror skiptostep 119, if
SCADA control is not available.
146. Keep L/R selector switch in REMOTE.
147. Execute the Close command from SCADA to close
the Circuit Breaker.
148. KeepL/Rswitchin local mode use “TNC” switch to
close the breaker.
149. If any problem found while closing, rectify the
problem or contact Shift-in-charge.
150. If breakergetsclosed,follow further instructions.
151. Ensure the healthiness of all relays, Trip circuit,
spring charge, all indication lamps & any other
installed equipment and SCADA HMI status after
closing the breaker.
152. Log out as “OPERATOR” as login as “MONITOR” in
SCADA.
153. Note downthe eventsinlogbookasmentioned in
step 67.
154. Inform site in-charge/ NMDC in-charge.
F. STEPS TO BE FOLLOWED TO SWITCH-OFF 6.6KV
OUT GOING FEEDER:
155. Ensure whether downstream consumer has
requested for switching OFF the feeder.
156. If yes, follow further instruction mention below.
157. Doubly Ensure the Feeder no.& Tag Name
158. Loginthe SCADA as Operator, if not available skip
12. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
to step 107
159. Keep L/R selector switch in REMOTE.
160. Execute the OPEN Command to switch OFF the
breaker
161. KeepL/Rswitchin local mode use “TNC” switch to
open the breaker.
162. Follow steps from 60 to 67.
G. STEPS TO BE FOLLOWED TO ENGAGE BUS
EARTHING TRUCK.
163. Bus earthing will be done during maintenance.
164. Get the clearance from downstream consumers.
165. Ensure PTW is issued from authorised person.
166. Switch OFF the IC, as per SOP mentioned in clause
“B”, of the bussectionwhichisgoingto be earthed.
167. SwitchOFFthe BC,,as perSOP mentionedin clause
“D”, if the bus section is energised through OTHER
IC.
168. Ensure that Bus is in Dead condition which is to be
earthed.
169. Doubly ensure that respective BUS Section is
isolated from primary source (i.eIC&BC Breaker &
TP Bus Link).
170. Ensure Bus PT voltage of respective section is zero.
171. Ensure that all O/G breakers are switched off and
isolatedfromrespective Bus section (To avoid back
feed from Downstream).
172. Keepthe breakersof all the outgoing feeder in test
position.
173. Ensure Earthing Truck is healthy and check the
tightnessandcontinuityof polestogroundingstrip.
174. Isolate one of the breakers of outgoing feeders
from the panel and Rack in the Bus Earth truck in
the outgoing panel of respective bus section..
175. Check that there is NO buzzer active in Earth truck.
176. Close the Earth truck bypressingthe FEB close push
button in Panel.
177. Tag the LOTO in Bus Earth truck engaged panel and
also in IC & BC panel.
178. Follow steps 66 to 67.
H. STEPS TO BE FOLLOWED TO ENGAGE FEEDER
EARTHING TRUCK.
179. Ensure that Isolation permit was taken for
respective feeder.
180. Get clearance from Downstream In-Charge to
engage the Feeder Earth Truck.
181. Ensure that the Feeder Earthing Truck is healthy
and check the tightness and continuity of poles to
grounding strip in CB –ON.
182. Rack out and isolate the breaker from the
respective panel.
183. Rack in the Earth truck inrespective feederwhich is
going to be earthed.
184. Check that there is NO buzzer active in Earth truck.
185. Close the Earth truck bypressingthe FEB close push
button.
186. Tag LOTO in respective Feeder (Earth truck
engaged).
187. Follow steps from 66 to 67.
I. EMERGENCY CONDITION
188. IF complete DC CONTROL SUPPLY OF SUBSTATION
FAILS, Switch OFF the breakers of all the incomers
of 33 kV GIS immediately.
189. IF DC CONTROL SUPPLY OF A FEEDERFAILS, Switch
OFF the breakers of that feeder.
190. If any of the outgoing feeder of 6.6 kV AIS fails to
trip from REMOTE as well as LOCAL, use “PULL TO
TRIP”, providedinthe rightside of panel,totrip the
breaker.
191. If “PULL TO TRIP” doesnot work,trip the IC breaker
or BC breaker of respective bus section using TNC
switch or “PULL TO TRIP” if TNC switch doesn’t
work.
192. IF IC breakerorBC breakeralso fails to trip, trip the
correspondingGIStransformerfeederorBC feeder.
193. If 33 kV GIS fails to trip, take shutdown from
upstream.
J. GENERAL INSTRUCTION:
a) Follow propersafety protocol.
b) Ensure valid PTW is available and returned after
job completion.
c) Conduct TBT before operation.
d) Inform your in-charges before & after the
operation.
e) Ensure full preparedness before operation.
f) Don’t be in hurry.
g) Don’t leave the site just after the operation.
13. NMDC
STANDARD OPERATING PROCEDURE OF6.6KV –SWITCH BOARD
Document Code : SOP/MV-6.6KV/Rev:00
h) All operation should be done from CCC (Central
Control Center).
i) Observe the systemregularly after each operation.
j) After operation of GIS, check all the electrical
equipment of substation.
k) Ensure Fire Fighting system is working.
l) Ensure housekeeping at workplace.
m) Shift should be handed over properly.
REFERENCE:
1. BHEL - VM12 TYPE VCB & MV METAL CLAD
6.6KV AIR INSULATED SWITCHGEAR - O&M
Manual
