This document provides comprehensive information on medium voltage (MV) switchgear, including types, designs, electrical ratings, testing standards, and essential protective features. It emphasizes the significance of proper installation, maintenance, and protection of electrical equipment to ensure reliability and safety. Additionally, it discusses the benefits of IEEE membership and the associated costs for joining.

1. IMRAN ZAFAR
Country Manager – Enercon Pakistan
Member Local Council – IEEEP Karachi Centre
Secretary – IEEE PES Society
WhatsApp : +92 335 2224287
E-mail : imran@enercon-eng.com.sg
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2. 2
MV SWITCHGEAR
Network Location
Technology
Electrical Ratings
Application in Circuit
Everything You Would Need To Know…

3. Electrical Network in Pakistan
3
WAPDA
K-Electric
IPPs
PAEC
NTDC
K-Electric
GRID STATION
DISCOs
K-Electric
SUBSTATION
13-18kV
500kV, 220kV , 132kV
11kV
11kV400V

4. 4
Types of Electricity Consumers
Transmission line
500, 220, 132kV
220kV /132kV
Consumer
11kV Consumer
400V Consumer
230V Consumer
Own Generation
Power Generation
Up to 18kV

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MV Switchgear – Types (Based on Network Position)
primary
distribution
up to 36 kV
feeder current
up to 630 A
Customer
Trans-
fer Substation
Distribution
Substation
secondary
distributio
n
up to 24 kV
feeder current
up to 630 A
Utility
Ring Main Unit
Secondary
Distribution
Primary
Distribution

6. 6
AIR
INSULATED
GAS
INSULATED
MV Switchgear – Types (Based on Technology)
MV Switchgear Video

7. 7
MV Switchgear Design in Pakistan

8. 8
MV Switchgear – VCB Trolley Design
Cable Compartment
BUSBAR
Compartment
Low-voltage compartment
BUSBARS
VCB
VCB Trolley
CTs
Cables
Earthing Switch
PTs
LV Compartment
VCB Compartment

9. 9
MV Switchgear – Truck Type Design
Low-voltage compartment
BUSBARS
VCB
VCB Truck
CTs
PTs
Cables

10. 10
MV Switchgear –WAPDA / KE GRID DESIGN
KESC / WAPDA GRID
LV compartment
BUSBARS
VCB
Door + VCB Trolley
CTs
PTs
Cables

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Type & Routine Test According to IEC – 62271-200
TYPE TEST (MANDATORY)
 Tests to verify insulation level
 Tests to prove temperature-rise
 Tests to prove the capability of main and earthing circuits with
rated peak withstand current and short-time withstand current
 Tests to prove making and breaking capacity
of included switching devices
 Tests to prove satisfactory mechanical functions
 Tests to verify the protection of personal safety
 Tests of internal arc classification
(mandatory type test, where applicable)
ROUTINE TEST
 Dielectric test of main circuit
at power-frequency voltage
 Test of auxiliary and control circuits
 Evidence of mechanical functioning

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Ventilation duct necessary for
installations with ceiling height less
than 4 Metre:
5 criteria are defined, all 5 criteria must be tested and
evaluated positively without exception
Criterion 1: Doors and covers remain closed
Criterion 2: No parts must fly off (>60 g)
Criterion 3: No holes in accessible sides
Criterion 4: No indicators may ignite
Criterion 5: Earth connections remain effective
Internal Arc Classification IAC A FLR

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8-15µΩ
>6<20mm
10-9 Bar
Interrupter bottles with laser welding in vacuum corner
Achieve High Di-electric Strength with only 6-10mm due to low pressure.
Vacuum Interrupter Video

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VCB COILS & RELEASES

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Operating Times Operating times at rated voltage of secondary
circuit

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Electrical Terms for MV Switchgear
3.3, 3.6, 4.8, 6.6 KV
20kV, 22kV
Rated Voltage
 Applicable Standard (IEC, NEMA, BS, etc.)
 Rated Voltage, Service Voltage,
 Short Duration Power Frequency Withstand Voltage
 Basic Impulse Lightning Test Voltage
 Correction Factor
10kV , 11kV
13.8kV, 15kV
Electrical
Ratings
33kV
Service VoltagePower Frequency Voltage
BIL Voltage

18. 18
Electrical Terms for MV Switchgear
Rated Current
630A, 800 A
1250 A, 1600A
2000A , 2500A
3200A, 4000A
Rated Short Circuit
20kA
25kA
31.5kA
40kA , 50kA
Rated Frequency
50 Hz , 60Hz
 Rated Current, Rated Busbar Current, Rated Feeder Current
 Service Current ,
 Short-Circuit Making Current , Short-Circuit Breaking Current
 Rated Frequency
Electrical
Ratings

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Electrical Ratings Variant 1 Variant 2 Variant 3
Rated voltage, max. kV 12 17.5 24
Rated short-circuit
current, max.
kA 25 31.5 40/50 25
Rated busbar
current, max.
A 2500 2500 4000
Rated feeder current,
max.
A 1000 1250 2500 2000 2500 2500 4000
1250A, 2500A BB, 31.5kA , 12/28/75kV , 50Hz
How you would specify Complete Rating of MV Switchgear ?

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Altitude Correction Factor

21. 21
132
/
11kV Typical MV Line-up

22. 22

23. 25
What You Need to Have in Your MV Switchgear?
Features Incomer
Panel
Feeding to
Transformer
Feeding to
Downstream Feeder
Feeding to Motor
Basic Protections
Relays
Yes Yes Yes Yes
Special
Protections
BUSBAR
Diff
Bucholz,
Differential
Directional ,
Distance
Differential
Ammeter
Voltmeter
Yes Yes Yes Yes
Energy Meter Yes Depending on Customer Wish
Test Plug Optional Choice, depend on Budget & Specs
VCB Motor
VCB UVT coil
Yes, if you need to operate your VCB via Electrical Switch or through Remote
Trip Circuit
Supervision
Optional Choice, depend on Budget & Specs
VCB Operation
Counter
Yes Yes Yes Yes

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What You Need to have in your Switchgear?
Features Incomer
Panel
Feeding to
Transformer
Feeding to
Downstream
Feeder
Feeding to
Motor
Earthing Switch Yes Yes Yes Yes
Earthing Switch
blocking Coil
Yes NO NO NO
Surge Arrester Yes Yes Yes NO
Surge limiter NO NO NO YES
Voltage Transformer Yes, If you need to measure voltage
Current Transformer YES, Core 1 – Protection , Core 2 – Metering,
Core 3 – Differential if needed
Thermostat &
Heaters
Yes, Considering Environmental Condition

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What You Need to have in your Switchgear?
Additional Indications / Remote Status
VCB Status Signal (ON, OFF , TRIP )
VCB Trolley Position Status (Service , TEST)
Earthing switch Status (ON, OFF)
Standard Interlocks
Capacitive Voltage Indicators

26. 28
Current & Voltage Transformers
Measuring CTs
Potential Transformer
Protection CTs

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A
B
C
D
E
Earthing Switch

28. 30
Surge Arrestors

29. 31
The Purpose of Protection…
The damages aredue to:
 Short Circuitin system
 Abnormal condition in the system
The Protection can not prevent system faults andabnormal conditions
 But it can
 limit the damage caused by short circuits andabnormal conditions.
While
 Protecting people andequipment from damage

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The Purpose of installation of protection relay is…
 To protect the veryexpensive equipment likeTransformers, Generators, Motors, Cables and
other installed equipment.
 To ensurethe interruption of supply to minimumnumberof consumers.
 To minimise the production losses of thefactories.
 To avoid major Countrylevel shut downs.

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MV Switchgear – Basic Protections
1. Over Current Protection
2. Short Circuit Protection
3. Earth Fault Protection
1. Motor Protection
2. Transformer Protection
3. Line Protection
4. Capacitor Protection
1. Main Protection
2. Back up Protection
WithRespect to Application
WithRespect to Devices
WithRespect to Fault

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MV Switchgear – Basic Protections
• O/L, S/C and E/F protection
• Phase sequence protection
• Surge protection
• Reverse power protection
• Thermistor protection
Generators
• O/L, S/C and E/F protection
• Thermistor protection
• Phase sequence protection
• O/V & U/V protection
•Thermistor protection
Motors
• O/C, S/C and E/F protection
• Bucholz protection
• Differential protection
Transformers

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1. Provides service reliability.
2. Ensures longer life of switchgear.
3. Minimizes fault probability.
4. Increases productivity.
5. Ensures Safety of personnel
6. Saves Investment.
Finally , Maintenance of MV Switchgear, Why it is so Important?

34. How to do Maintenance of VCB ?
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1. Rack out the trolley in disconnected position.
2. Clean all the dust with the help of cotton cloth from
upward to downward position.
4. Open the VCB front cover plate.
5. Clean the parts with the help of cotton cloth wherever
possible.
6. Apply the WD40 spray on mechanical parts.
7. Apply the petroleum jelly on slow moving parts such as
bearing, Connection Jaws etc.
8. Close the VCB front door.
9. Clean the insulator on VCB trolley as much as you can do.
10. Apply Silicon spray on insulators.

35. Maintenance of MV Switchgear, Tips…
38
1. Remove the back plate of the panels.
2. Clean all the insulators properly & apply Silicon spray.
3. Clean the compartment with the help of vacuums
cleaner or cotton cloth.
4. Check all the power & control cable connections
for proper tightening.
5. Special attention to be paid on HT insulation kit.
6. Open the LT compartment door.
7. Check all the connection for tightness.
8. Bring the trolley on test position and connect the control plug.
9. Circuit of Anti Condensation Heater should be checked.
10. Heater should be ON when panel is not energized to kill moisture.

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How IEEE Membership benefit you?
• Giving back to Society
• Social Networking & Connection with Community
• Number of Tangible & Intangible Benefits

37. 40
Becoming A Member of IEEE
If you don’t have credit card:
• Send IEEE Account number, Password and payment to mohd_shahab@hotmail.com.
• Total payment in PKR = (13.50*169) + 7 per USD
= 2375 PKR
Note:
• 169 is today’s dollar rate. It might change
• PKR 7 per USD for taxes on foreign transaction / other charges.
Career Phase Price
Student USD 13.50 (For half year)
Professional USD 79.00

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