Areva T&D WI User manual

AREVA T&D
Technical Instructions
WI
Gas-Insulated switchgear
single/two phase version 55 kV
Operating Instructions
No. AGS 531 491-01
Edition 09/2009
>>
GAS-INSULATED SWITCHGEAR

AREVA T&D Worldwide Contact Centre
http://www.areva-td.com/contactcentre/
[phone]
http://www.areva-td.com
Manufacturer:
AREVA Energietechnik GmbH – Sachsenwerk Medium Voltage
Rathenaustraße 2
D-93055 Regensburg, Germany
+49 (0) 9 41 / 46 20-0
 +49 (0) 9 41 / 46 20-418
Service:
Should you have any queries as to our service, please contact:
AREVA Energietechnik GmbH – Sachsenwerk Medium Voltage
Service-Center
D-93055 Regensburg, Germany
+49 (0) 9 41 / 46 20-777
 +49 (0) 9 41 / 46 20-778
©AREVA Energietechnik GmbH, Sachsenwerk Medium Voltage -2009-
All rights reserved to this technical instruction.
Reproduction and making available of this technical instruction, or extracts, to third parties are prohibited. Only the complete reproduc-
tion of this technical instruction is permitted by written permission from AREVA Energietechnik GmbH, Sachsenwerk Medium Voltage.
Electronic copies, e.g. as PDF format or as scanned version, have the status “for information only”.
The only valid technical instructions are those which are supplied directly from the manufacturer with the delivery of the product.

3
1 Regulations and provisions 4
1.1 Introduction 4
1.2 Terms and symbols used 4
1.3 Use in line with the intended purpose 4
1.4 Applied standards 5
1.5 Safety provisions 6
1.6 Disposal after the end of the
useful life 6
2 Technical data, control and
operating devices 7
2.1 Type designation 7
2.2 Control and operating devices
8
3 Panel type overview 10
4 Voltage detection systems 12
4.1 HR-System 12
4.2 IVIS 12
4.3 Phase comparator 12
5 Operation 13
5.1 Operator interfaces and variants for WIA 13
5.2 Interlocks 15
5.2.1 Mechanical interlocks 15
5.2.2 Electromechanical interlocks 15
5.2.3 Key locking of mechanical operation
5.2.4 Interlocking of various panel types 16
5.2.4.1 Incomer and feeder panels 16
5.2.4.2 Bus section coupler 16
5.2.4.3 Bus sectionalizer 19
5.2.4.4 Busbar earthing switch 20
5.3 Switching operation - circuit-breakers,
disconnectors, earthing switches 21
5.4 Standard switching operations 24
5.5 Earthing the busbar 25
5.6 Isolating the voltage transformer 27
6 Cable test 28
7 Insulating gas, tanks 29
8 Servicing 31
8.1 General 31
8.2 Servicing schedule 31
8.3 Lubrication instructions 32
8.4 Exchange of voltage transformers 36
8.5 Permissible number of break operations 38
9 Annex 39
9.1 Screw and bolt connections 39
9.2 Auxiliary products 39
9.3 Accessories 39
Contents
>>

4
1.1 Introduction
These Technical Instructions de-
scribe the operation of gas-insulated
WI medium-voltage switchgear.
These instructions are an integral
part of the product. It must be made
available at any time to the persons
who work on the switchgear.
The following additional documents
for this switchgear must be ob-
served:
•Purchase contract with the agree-
ments on the configuration of the
switchgear and with the legal
details
•Installation Instructions
•the wiring drawings for the whole
switchboard
•the Operating Instructions of the
devices installed in the switchgear
(e.g. IVIS, devices in low-voltage
cabinet)
•the Instructions for Assembly pro-
vided by the manufacturer of the
cable connection systems to be
connected to the switchgear
•the System Configuration “WI”
As our products are subject to con-
tinuous further development, we
reserve the right to make changes
regarding standards, illustrations and
technical data.
1.2 Terms and symbols
used
This manual uses certain symbols
which warn about dangers or pro-
vide important information which
must be observed to avoid danger
to personnel and damage to equip-
ment:
Warning!
This symbol warns of
dangerous electrical
voltage. Contact with
live parts may result in fatal
injury!
Warning!
This symbol indicates
important instructions.
Non-compliance may
result in serious injury, death
or damage to the equipment.
Important!
This symbol is used for
information which is impor-
tant to avoid damage.
1.3 Use in accordance
with the intended
purpose
WI gas-insulated medium-voltage
switchgear units are exclusively
intended for switching and distribu-
ting electrical power. They may only
be used in the scope of the speci-
fied standards and the appropriate
switchgear-specific technical data.
Any other use constitutes improper
use and may result in dangers and
damage.
Disclaimer of liability
The manufacturer shall not be held
responsible for damage which
occurs if:
•instructions in this manual are not
complied with,
•the switchgear is not operated
according to its intended use
(see above),
•the switchgear is assembled,
connected or operated improperly,
•accessories or spare parts are
used which have not been appro-
ved by the manufacturer,
•the switchgear is modified without
the manufacturer’s approval, or if
inadmissible parts are attached.
No liability is accepted for parts
provided by customers, e.g. current
transformers.
1 Regulations and provisions
>>

5
1.4 Applied standards
WI switchgear units are
•metal-enclosed
•SF6insulated
•type-tested
Designation IEC standard EN standard
Switchgear IEC 62271-1 EN 62271-1
IEC 62271-200 EN 62271-200
– EN 50124-1
Circuit-breaker – EN 50152-1
Earthing switch – EN 50152-2
Disconnector – EN 50152-2
Current transformer IEC 60044-1 EN 60044-1
Voltage transformer IEC 60044-2 EN 60044-2
Voltage detection systems IEC 61243-5 EN 61243-5
Protection against accidental
contact, foreign objects and water IEC 60529 EN 60529
Installation IEC 61936-1 HD 637 S1
Operation of electrical equipment – EN 50110
WI switchgear units meet the following standards and regulations:
WI switchgear may only be operated
under normal operating conditions
according to the IEC Publication
IEC 62271-1.
Operation under conditions deviating
from these is only admissible upon
consultation with and approved by
the manufacturer.
1) Other values possible on request
Ambient conditions (acc. to IEC 62271-1)
Temperature class ”Minus 5 indoors”
Min./max. ambient temperature °C -5 / 40 1)
Average value over 24 hours °C ≤35 1)
Average rel. air humidity: 24 h / 1 month % ≤95 / 90
Max. installation altitude above sea level m ≤1000 1)
2) optional: IP 52
Degree of protection against accidental contact and foreign objects
(acc. IEC 60529)
Main electric circuits IP65
Drives IP2X
Low-voltage cabinet IP3X 2)
Insulating gas (acc. to IEC 60 376)
Type Sulphurhexafluorid (SF6)
Rated pressure pre at 20 °C MPa 0.22
Environmental and operating conditions

6
1.5 Safety provisions
The user shall ensure that the work
described in this manual is carried
out only by the manufacturer‘s Ser-
vice Centre staff, or by personnel
qualified and authorized to assemble
and test WI switchgear.
Read these instructions carefully
before starting work on the switch-
gear, and perform the work detailed
in them as described. Do not per-
form any work on the switchgear
panel which is not described in this
technical instruction.
Applicable standards and regu-
lations:
Please comply with:
•the locally applicable health
and safety, operating and work
instructions
•Installation:
IEC 61936-1 / HD 637 S1 1)
•Operation of electrical installa-
tions:
EN 50110-1 1)
1) The national standards applicable
in the country where the equip-
ment is to be installed must be
complied with.
Important!
Operating reliability and
useful life depend on correct
operation.
Before performing work on the
panel, make sure to comply with the
following instructions:
Warning!
Before starting work on
the high-voltage com-
ponents, de-energize
the system, verify it for zero
voltage and earth the system
according to the applicable
safety rules pursuant to
EN 50110-1.
Warning!
Before performing work
on the drives, switch off
the auxiliary voltage
and prevent it from reclosing.
Warning!
There is a risk of injury
when working on the
drive mechanism.
Release the circuit-breaker’s
energy storing device by per-
forming the corresponding
•OFF-ON-OFF operating
sequence.
•in case of a make-proof
earthing switch, by the
appropriate ON-operation.
Action in the event of incidents or
accidents
The WI switchgear panels feature
pressure relief ports for the case
of an internal arc fault to ensure
operator safety.
In case of fire or of internal faults,
toxic and caustic decomposition
products may arise. Comply with the
locally applicable health and safety
provisions.
In the event of injury to personnel,
ensure that appropriate first-aid
measures are taken.
1.6 Disposal at the end
of service life
A material and recycling data sheet
can be provided on request for the
disposal of series WI switchgear at
the end of its service life:
Disposal is performed as a service
by the manufacturer’s Service Cen-
ter which is subject to a fee.
The operating equipment contains
the fluorinated greenhouse gas SF6
mentioned in the Kyoto protocol with
a global warming potential (GWP) of
22 200.
SF6must be recovered and must
not be released into the atmosphe-
re. When using and handling SF6,
comply with the specifications in the
standard IEC 62271 High-Voltage
Switchgear and Controlgear – Part
303 Use and Handling
of Sulphur Hexafluoride (SF6).

7
2.1 Type designation
The type designation of the switch-
gear panels - see name plate -
informs about
•design
•rated peak withstand current
•rated voltage
•dimensions
Example: W I A 6 / 5 5 - T / 6 2 6
Series WI
Single busbar A
Rated peak with-
stand current 63 kA
Rated
votage 55 kV
S single phase version
T two phase version
Dimensions:
Panel width 600 mm
Panel height 2664 mm
(3020, by enlarged bottom
and front cover plate)
In case of queries and orders for
spare parts, the following data on
the name plate must be specified:
- Type designation
- Serial number
- Year of manufacture
1
23
4
Fig. 2.1
Name plate
1 Type designation
2 Serial number
3 Year of manufacture
4 Rating (see also IEC 62271-200)
2 Technical data, control and
operating devices
>>

2.2 Control and operating
devices
The drive mechanism is designed
on principle for manual charging of
the energy storing device (closing
spring).
The drive can be equipped with
additional operating and control
devices which are characterized
according to the LV wiring diagram
for the whole switchboard.
Component fitting options:
Motor
•for charging the energy-storing
device (closing spring)
•for actuation of the disconnector
and earthing switch
Closing release
•1 unit
Opening release
•max. 2 units
Secondary release
(CT-powered release)
•max. 2 units
•(Maximum equipment – opening
release and secondary release,
3 units in total)
Undervoltage release
•1 unit
Blocking coil
Blocking coils prevent the circu-
it breaker from being closed and
opened via the mechanical push-
buttons “ON“ or “OFF“, as well as
actuation of the interlocking levers
of the disconnectors and earthing
switches.
Operating counter
•The operating counter indicates
the number of switching opera-
tions.
8
Power consumption, solenoids and motor
Power consumption
DC AC 50/60 Hz
approx. [W] approx. [VA]
Closing release 160 160
Opening release with
auxiliary spring energy store 25 25
Undervoltage release 15 15
CT-powered release – 12
Blocking coil 12 12
Motor 200 - 250 200 - 250
Please enquire at the manufacturer’s for details of the motor’s starting current.
The auxiliary voltage data is required to this effect.
Times for solenoids and motor
Minimum command time
„OFF“ el. tripping [ms] 50
Minimum command time
„ON“ [ms] 20
Motor charging time [s] ≤ 12

9
Adjustment of Auxiliary Switches
Auxiliary switches are always actua-
ted directly by the switch shaft via an
intermediate linkage. Their position
always corresponds to that of the
main contacts.
Please take current adjustment of
auxiliary switches from the latest
revision of switchboard‘s LV sche-
matics.
Auxiliary switches may not be disas-
sembled.
Rated supply voltage DC
Switching capacity
Time constant T=L/R
Rated short-time current
[V]
[A]
24
8
[ms] ≤ 20
100 A for a duration of 30 ms
48
4
60
3
110
2
220
1
Rated continuous current [A] 10
AC
120
10
230
10
–
Auxiliary switch

10
3 Panel type overview
>>
1
2
3
14
4
5
15
7
6
8
10
9
11a
12
13
Fig. 3.1
Circuit breaker panel, single/two phase design, 2 cable termina-
tion sockets per phase, busbar and circuit connected voltage
transformer
Fig. 3.2
Bus Sectionalizer panel two phase design
-25kV
B2
+25kV
B1
3
14
4
16
15
12
13
1 Over pressure release circuit-breaker tank
2 Circuit-breaker tank
3 Busbar tank
4 Disconnector / earthing switch
5 Vacuum circuit-breaker
6 Ring core current transformer
7 Density gauge circuit-breaker tank
8 Voltage transformer disconnector (optional)
9 Metal-enclosed voltage transformer (optional)
10 Socket size 3 for voltage transformer termination
11 Socket size 3 for HV cable termination per phase –
11a Socket size 3 for double HV cable termination per phase
11b Socket size 3 for single HV cable termination per phase
12 Panel supporting frame
13 Low voltage cabinet
14 Front cover plate
15 Circuit-breaker, disconnector,
earthing switch drive cabinet
16 Over pressure release busbar tank
1
Fig. 3.3
Riser Panel (no circuit breaker), 1 cable termination socket per
phase, busbar connected voltage transformer
2
3
14
4
15
7
6
8
10
9
11b
12
13

11
1
Fig. 3.4
Bus section panel with circuit-breaker
2
3
9
4
5
10
7
6
12
8
1 Over pressure release circuit-breaker tank
2 Circuit-breaker tank
3 Busbar tank
4 Disconnector / earthing switch
5 Vacuum circuit-breaker
6 Ring core current transformer
7 Density gauge circuit-breaker tank
8 Low voltage cabinet
9 Front cover plate
10 Circuit-breaker, disconnector,
earthing switch drive cabinet
11 Over pressure release busbar tank
12 Panel supporting frame
17 Interconnecting tank
1
17
17
Fig. 3.5
Bus riser panel
2
3
9
4
10
7
6
12
8
A
B
E
C
D
Fig. 3.6
Single busbar, WIA up to 55 kV
A Drive with front control panel operation unit
B Tank with circuit-breaker, disconnector and earthing switch
C Busbar tank
D Supporting structure with cable connection area
E Low voltage cabinet

4.2 IVIS (Intelligent Voltage
Information System)
A fixed mounted indication unit is
used to indicate presence of high
voltage for each phase via a black
high voltage lightning symbol.
The unit is located at panel‘s front
and rear side providing a permanent
indication.
It is complying with IEC 61243-5
and featuring indicating limits speci-
fied in this publication.
The system is maintenance-free and
does not require external power
suppl
Important!
Observe the Operating
Instructions of the IVIS
system.
4.1 HR-System
(High Resistance System)
Separate plug-in type indicators are
used to determine presence of high
voltage via a neon glow lamp. Indi-
cators are plugged into test sockets
located at panel‘s front underneath
the drive mechanism cabinet and
rear side. Indication system is com-
plying with IEC 61243-5 and featu-
ring indicating limits specified in this
publication. Only indicators supplied
by authorized manufacturers may be
applied.
Warning!
The indicators must not
be plugged in at the
front and rear simulta-
neously (offset response limits).
Important!
Observe the Operating
Manual of the voltage
indicators used.
Important!
All phases L1 and L3
must always be checked.
12
4 Voltage Detecting Systems (VDS)
Two capacitive voltage indication systems are in use
ensuring phase is live (energized) and phase is dead
(deenergized) indication.
>>
Fig. 4.1
Horstmann indicator (HR-ST)
Fig. 4.2
Metering sockets for the continuous voltage
indicator
Fig. 4.4
Phase comparator device for system HR,
type Orion 3.0 (manufacturer: Horstmann
GmbH)
Fig. 4.5
Phase comparator MS 100 for the
IVIS-system
4.3 Phase comparator
Phase sequence must be checked
before a new or refurbished high vol-
tage system is going to be connec-
ted to the already exsisting.
Voltage detecting systems together
with a phase comparator available as
optional accessory can be used to
check phase sequence.
HR-System
Phase comparator type Orion 3.0
manufactured by Horstmann GmbH,
Germany is available.
Please refer to associated operation
instructions for application and furt-
her details.
IVIS
Phase comparator type MS 100
manufactured AREVA Sachsenwerk
GmbH, Germany is available.
Please refer to associated operation
instructions for application and furt-
her details.
Fig. 4.3
1 IVIS on the panel front side
2 IVIS on the panel rear side
1
2

13
0,5
SF6
bei 20°C
KL1.0 bar
-0,5
-1,0
0
1,0
1,5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
All operation and indication devices are purely mechanical.
1 push button, circuit breaker ON (close)
2 push button, circuit breaker OFF (trip)
3 opening to put in crank handle for circuit breaker spring charging
4 position indicator circuit breaker spring charging (spring free, spring charged)
5 position indicator circuit breaker
6 position indicator earthing switch
7 opening to put in crank handle for earthing switch operation
8 interlocking lever earthing switch
9 position indicator disconnector
10 opening to put in crank handle for disconnector operation
11 interlocking lever disconnector
12 optional device to lock mechanical operation of circuit breaker,
disconnector and earthing switch
13 name plate
14 density gauge monitoring insulating gas
15 circuit breaker operations counter
16 label
Fig. 5.1
Example: Operation unit feeder panel
5.1 Mechanical operation and control units for various panel types
5 Mechanical Operation and Control
>>

14
0,5
SF6
bei20°C
KL1.0bar
-0,5
-1,0
0
1,0
1,5
0,5
SF6
bei20°C
KL1.0bar
-0,5
-1,0
0
1,0
1,5
0,5
SF6
bei20°C
KL1.0bar
-0,5
-1,0
0
1,0
1,5
Further panel types
Feeder, incomer Bus section riser
Bus sectionalizer
Bus section coupler with
circuit breaker

15
5.2 Interlocking
5.2.1 Mechanical
Interlocks
•Each operation procedure must
be duly carried out (at one of the
both possible end positions) prior
to commencing the next opera-
tion.
•Simultaneous operation of interlo-
cking levers is not possible!
•Crank handle for disconnector or
earthing switch operation can be
removed only, if belonging drive
mechanism has reached its end
position.
•Earthing switch can only be
moved into ON postion if circuit
breaker spring is charged. (The
circuit-breaker is switched ON
automatically after reaching the
earthing position, see sect. 5.3.)
Reverse actuation during the
switching operation is prevented.
Each actuation of the earthing
switch must be performed to its
end.
•Circuit breaker cannot be swit-
ched ON (close) if:
- crank handle for disconnector or
earthing switch operation
has not been removed
- interlocking lever is actuated
(Means: Circuit breakers mecha-
nical push button ON (close),
and its electrical remote control
are blocked. This applies for bus
section panels circuit breakers as
well.)
5.2.2 Electromechanical
interlocks
In addition to mechanical interlocking
electro-magnetic blocking coils are
used for realization of interlocking:
- between adjacent panels within
a switchboard (for example
busbar earthing)
- between panel and external
located panel (for example
between earthing switch incomer
and earthing switch of infeeding
high voltage panel)
- between panel‘s switching
device and a solenoid switch
located in its low voltage cabinet
Number of blocking coils and their
location depend on switchboard‘s
interlocking configuration and can be
taken from the associated low volta-
ge schematics.
5.2.3 Key locking of
mechanical
operation
Optionally two alternatives are availa-
ble to lock mechanical (manual) ope-
ration of circuit breaker, ON (close),
disconnector and earthing switch.
A label sticked close to key locking
points to a incomplete interlocking
scheme.
Important!
Depending on switchboard‘s
interlocking configuration the
key locked operation is sup-
posed to be applied under special
circumstances only.
Alternative 1:
Central key locking featuring a
cylinder lock.
Turning a key means moving a plate
which prevents to press of circuit
breaker ON (close) push button.
(Blocking of circuit breaker OFF
(trip) on special request only.)
Furthermore opening to put crank
handle for disconnector and earthing
switch operation is blocked.
Alternative 2:
Padlocking
A padlockable cover is installed to
enable padlocking of circuit breaker
on (close) push button (device for
circuit breaker OFF (trip) supplied on
special request only).
Padlockable interlocking levers for
disconnector and earthing switch are
fitted.
Warning!
Provision of complete
interlocking may be
ensured by electrical
operation only.
Warning!
Before operating
switchgear refer to
specific low voltage
schematics first!
0,5
SF6
bei20°C
KL1.0 bar
-0,5
-1,0
0
1,0
1,5
Attention!
No interlocks are effective
in case of manual actuation
1
2
Fig. 5.2
Alternative 1: Central Key Locking
1 Mechanical lock-out mechanism with
cylinder lock
2 Information plate (enlarged)
Mechanical lock-out mechanism
pad lockable (optional)
Fig. 5.3
Alternative 2: Padlocking
1 pad lockable lid for push button
2 pad lockable lever
1
2

ON
OFF
Bus Zone 2 (BZ2)
blocking coil
Bus Zone 1 (BZ1)
16
5.2.4 Interlocking of various panel types
In case of remote control interlocking will perform accordingly.
5.2.4.1 Incomer and feeder panels
Important!
As per 5.2.2 interlocking
scheme may depart from
the above.
5.2.4.2 Bus section coupler (consisting of bus section circuit-breaker and riser panel)
Usually a bus section coupler inter-
locking scheme applying a mixture
of mechanical (as per 5.2.3.1) and
electrical interlocks using blocking
coils is installed.
These blocking coils ensure safe
switchboard / bus section coupler
operation if bus zones have to be
separated, reconnected or earthed.
They are mounted at drive
mechanisme of:
•Bus section panel:
- earthing switch
- disconnector switch
- circuit-breaker ON (close)
and OFF (trip)
•Bus riser panel:
- earthing switch
- disconnector switch
•Incomer and feeder panels
- disconnector switch
Fig. 5.4
Principle of electromechanical interlocking
bus section coupler
Switching device position/ position/ position/ position/ position/
operation operation operation operation operation
Circuit-breaker ON ON OFF ON OFF
Spring charging – – – – discharged
3position switch:
Disconnector ON OFF ON OFF OFF
Interlocking lever blocked blocked free blocked free
Earthing switch OFF OFF OFF ON OFF
Interlocking lever blocked blocked blocked free free
Crank handle operation – – – – blocked
– not relevant for interlocking

17
Switching devices of bus section
panels (BS/BR) can be used to
earth either the busbars of BZ1 or
BZ2 by operation of:
- earthing switch located in BS
panel to earth BZ2 busbars
- earthing switch located in BS
panel to earth BZ1 busbars
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
a) Bus Zone Separation / Reconnection
b) Bus Zone (BZ) Earthing
Important!
Deviations from described
interlocking schemes may
occur. Therefore please refer
to switchboard specific low voltage
drawings also.
Further details of switchgear opera-
tion can be found in chapter 5.3/4/5.
^
^
BS = bus section panel
BR = bus riser panel
Switching devices BS position/ position/ position/
operation operation operation
Circuit-breaker ON OFF OFF
Spring charging – – –
3position switch:
Disconnector ON ON OFF
Interlocking lever blocked free free
Earthing switch OFF OFF OFF
Interlocking lever blocked blocked free
Crank handle operation
Switching devices BR position/ position/ position/
operation operation operation
3position switch:
Disconnector ON ON OFF
Interlocking lever blocked free free
Earthing switch OFF OFF OFF
Interlocking lever blocked blocked free
– not relevant for interlocking

Bus Bar Earthing Bus Zone 1 (BZ1)
18
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
BZ1 BZ2
BS BR
^
^
BS = bus section panel
BR = bus riser panel
^
^
BS = bus section panel
BR = bus riser panel
Bus Bar Earthing Bus Zone 2 (BZ2)
Switching devices BS position/ position/ position/ position/
operation operation operation operation
Circuit-breaker OFF OFF OFF ON
Spring charging charged discharged charged charged
3position switch:
Disconnector OFF ON ON ON
Interlocking lever free free free blocked
Earthing switch OFF OFF OFF OFF
Interlocking lever free blocked blocked blocked
Switching devices BR position/ position/ position/ position/
operation operation operation operation
3position switch:
Disconnector OFF OFF OFF OFF
Interlocking lever free free free blocked
Earthing switch OFF OFF OFF ON
Interlocking lever free blocked free 1) free
1) All incomer and feeder disconnectors of BZ1 must be in open position before earthing operations can be carried out.
Switching devices BS position/ position/ position/ position/
operation operation operation operation
Circuit-breaker OFF OFF OFF ON
Spring charging charged discharged charged charged
3position switch:
Disconnector OFF OFF OFF OFF
Interlocking lever free free free blocked
Earthing switch OFF OFF OFF ON
Interlocking lever free blocked free 1) free
Switching devices BR position/operation position/ position/ position/
operation operation operation operation
3position switch:
Disconnector OFF ON ON ON
Interlocking lever free free free blocked
Earthing switch OFF OFF OFF OFF
Interlocking lever free blocked blocked blocked
1) All incomer and feeder disconnectors of BZ2 must be in open position before earthing operations can be carried out.

Switching device position/ position/ position/ position/
operation operation operation operation
Bus sectionalizer
Disconnector ON ON OFF OFF
Interlocking lever free free free free
BZ1 earthing switch OFF OFF OFF OFF
Interlocking lever blocked blocked free free
BZ2 earthing switch OFF OFF OFF OFF
Interlocking lever blocked blocked free blocked
BZ1 disconnectors of
incomer / feeder panels all OFF ON all OFF all OFF
BZ2 disconnectors of
incomer / feeder panels all OFF all OFF all OFF ON
19
5.2.4.3 Bus sectionalizer
Usually an interlocking scheme
applying a mechanical (as per
5.2.3.1) and electromechanical inter-
locks using blocking coils (as per
5.2.2) is installed.
These blocking coils ensure safe
switchboard / bus sectionalizer ope-
ration if bus zones have to be sepa-
rated, reconnected or earthed.
They are mounted at drive
mechanism of:
•Bus sectionalizer panel:
- busbar disconnector
- earthing switch bus zone 1
- earthing switch bus zone 2
•Incomer and feeder panels:
- disconnector switch
a) Bus Zone Separation / Reconnection
BZ1 BZ2 BZ1 BZ2 BZ1 BZ2 BZ1 BZ2
blocking coil
Bus Zone 2 (BZ2)
Bus Zone 1 (BZ1)
Fig. 5.5
Principle of electromechanical interlocking bus
sectionalizer
^
^
BZ1 = Bus Zone 1
BZ2 = Bus Zone 2

20
blocking coil
BZ1 BZ2
^
^
BZ1 = Bus Zone 1
BZ2 = Bus Zone 2
5.2.4.4 Busbar earthing
switch
Busbar earthing switch installed insi-
de a separate busbar tank located
either on the left or right hand end
of switchboard.
An electromechanical interlocking
scheme using blocking coils (as per
5.2.2) is installed to ensure safe
busbar earthing.
Fig. 5.6
Principle of electromechanical interlocking
busbar earthing switch
Switching device position/ position/ position/
operation operation operation
Busbar earthing switch OFF OFF ON
Unlocking button blocked free free
Disconnectors of
incomer / feeder panels ON all OFF all OFF
Interlocking lever blocked blocked blocked
b) Busbar Earthing Bus Zone 1/2
BZ1 BZ2 BZ1 BZ2 BZ1 BZ2 BZ1 BZ2
Switching device position/ position/ position/ position/ position/
operation operation operation operation operation
Bus sectionalizer
Disconnector ON OFF OFF OFF ON
Interlocking lever free free blocked blocked free
BZ1 earthing switch OFF OFF ON OFF ON
Interlocking lever blocked free free blocked free
BZ2 earthing switch OFF OFF OFF ON ON
Interlocking lever blocked free blocked free free
BZ1 disconnectors of
incomer / feeder panels all OFF all OFF all OFF ON all OFF
Interlocking lever free free blocked free blocked
BZ2 disconnectors of
incomer / feeder panels all OFF all OFF ON all OFF all OFF
Interlocking lever free free free blocked blocked