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Low Voltage Switchgear Design & Calculation Presentation

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Low Voltage
Switchgear:
Design &
Calculation
Internal
OBJECTIVE
• To acquire basic LVSG design &
construction
• Understand the critical elements of
switchgear
• Calculate the equivalent busbar for
the LVSG
Internal
CONTENTS
• Definition
• Construction
• How to design?
Internal
DEFINITION – LVSG
• Designed for switching and protection
of low voltage equipment
• Used both to de-energize equipment
to allow work to be done and to clear
faults downstream
• LVSG range 24VDC – 690VAC
Internal
LVSG CONSTRUCTION
• Enclosure
• Busbar
• Incoming , outgoing
devices & auxiliary
Circuits
Internal
CONTENTS
• Definition
• Construction
• How to design?
Internal
ENCLOSURE
• A part providing a specified degree of
protection of equipment against certain
external influences and a specified
degree of protection against approach
to or contact with live parts and moving
parts
• Housing affording the type and degree
of protection suitable for the intended
application
Internal
ENCLOSURE
• Consists of the following:
• Functional unit
• Section
• Sub-section
• Compartment
• Partition
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit – part of an assembly comprising all
the electrical and mechanical elements that
contribute to the fulfilment of the same function
• Section
• Sub-section
• Compartment
• Partition
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit
• Section – constructional unit of an
assembly between two successive
vertical delineations
• Sub-section
• Compartment
• Partition
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit
• Section
• Sub-section – constructional unit of an
assembly between two successive
horizontal or vertical delineations of
compartment
• Partition
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit
• Section
• Sub-section
• Compartment – section or sub-section
enclosed necessary for
interconnection, control or ventilation
• Partition
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit
• Section
• Sub-section
• Compartment
Partition
• Partition – part of the enclosure of a
compartment separating it from other
compartments
• Barrier
• IP Rating
• Forms of Separation
Internal
ENCLOSURE
• Consists of the following:
• Functional Unit
• Section
• Sub-section
Barrier
• Compartment
• Partition
• Barrier – part providing protection
against direct contact from any usual
direction of access
• IP Rating
• Forms of Separation
Internal
IP RATING (IEC 60529)
Degrees of protection provided by
enclosures (IP Code)
IP XX
Internal
IP Rating (IEC 60529)
Description
Degrees of protection provided by enclosures
(IP Code)
IP XX
First Character
Protection against
ingress of solid foreign
objects
Internal
0
No Protection
1
Protected against solid foreign
objects of 50 mm ∅ and greater
2
Protected against solid foreign
objects of 12,5 mm ∅ and greater
3
Protected against solid foreign
objects of 2,5 mm ∅ and greater
4
Protected against solid foreign
objects of 1,0 mm ∅ and greater
5
Dust-protected
6
Dust-tight
IP Rating (IEC 60529)
Description
Degrees of protection provided by enclosures
(IP Code)
IP XX
Second Character
Protection against
ingress of water
with harmful effects
Internal
0
No Protection
1
Protected against vertically falling
water drops
2
Protected against vertically falling
water drops when enclosure tilted
up to 15°
3
Protected against spraying water
@ 60° on either side
4
Protected against splashing water
5
Protected against water jets
6
Protected against powerful water
jets
7
Protected against the effects of
temporary immersion in water
8
Protected against the effects of
continuous immersion in water
QUIZ # 1
IP 00
No protection at all
Internal
QUIZ # 2
IP 54
5 – Dust protected
4 – Protected against
splashing water
Internal
QUIZ # 3
IP 30
3 – Protected against solid
foreign objects of >2,5 mm
∅
0 – No protection against
water
Internal
QUIZ # 4
IP 65
6 – Dust-tight
5 – Protected against water
jets
Internal
QUIZ # 5
IP 31
3 – Protected against solid
foreign objects of 2,5 mm ∅
and greater
1 – Protected against vertically
falling water drops
Internal
NEMA
Rating
NEMA Definitions
Rating
NEMA Definitions
Enclosures constructed for either indoor or outdoor use to provide a degree of protection
to personnel against incidental contact with the enclosed equipment; to provide a degree
of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water,
hose-directed water, & corrosion; & that will be undamaged by thee external formation
of ice on the enclosure
Enclosures constructed for indoor use to provide a degree of protection to personnel
against incidental contact with the enclosed equipment; to provide a degree of protection
against falling dirt; against settling airborne dust, lint, fibers, & flyings; & to provide a
degree of protection against dripping & light splashing of liquids.
Enclosures constructed for either indoor or outdoor use to provide a degree of protection
to personnel against incidental contact with the enclosed equipment; to provide a degree
of protection against falling dirt; against hose-directed water & the entry of water during
occasional temporary submersion at a limited depth; & that will be undamaged by the
external formation of ice on the enclosure.
Enclosures constructed for either indoor or outdoor use to provide a degree of protection
to the personnel against incidental contact with the enclosed equipment; to provide a
degree of protection against falling dirt; against hose-directed water & the entry of water
during prolonged submersion at a limited depth; & that will be undamaged by the
external formation of ice on the enclosure
1
Enclosures constructed for indoor use to provide a degree of protection to personnel
against incidental contact with the enclosed equipment & to provide a degree of
protection against falling dirt
4X
2
Enclosures constructed for indoor used to provide a degree of protection to
personnel against incidental contact with the enclosed equipment, to provide a
degree of protection against falling dirt, & to provide a degree of protection against
dripping & light splashing of liquids
5
3
Enclosures constructed for either indoor or outdoor used to provide a degree of
protection to personnel against incidental contact with the enclosed equipment; to
proved a degree of protection against falling dirt, rain, sleet, snow, & windblown
dust; & that will undamaged by external formation of ice on the enclosure
6
3R
Enclosures constructed for either indoor or outdoor used to provide a degree of
protection to personnel against incidental contact with the enclosed equipment; to
provide a degree of protection against falling dirt, rain, sleet, & snow; & that will be
undamaged by external formation of ice on the enclosure
6P
3S
Enclosures are constructed for either indoor or outdoor use to provide a degree of
protection to personnel against incidental contact with the enclosed equipment; to
provide a degree of protection against falling dirt, rain, sleet, snow, & windblown
dust; & in which the external mechanism(s) remain operable when ice laden.
12 &
12K
Enclosures constructed (without knockouts) for indoor use to provide a degree of
protection to personnel against incidental contact with the enclosed equipment; to
provide a degree of protection against falling dirt; against circulating dust, lint, fibers, &
flying; & against dripping & light splashing of liquids
4
Enclosures constructed for either indoor or outdoor use to provide a degree of
protection to personnel against incidental contact with the enclosed equipment; to
provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust,
splashing water, & hose-directed water; & that will be undamaged by the external
formation of ice on the enclosure
13
Enclosures constructed for indoor use to provide a degree of protection to personnel
against incidental contact with the enclosed equipment; to provide a degree of protection
against falling dirt; against circulating dust, lint, fibers, & flyings; & against the spraying,
splashing, & seepage of water, oil, & noncorrosive coolants.
Internal
IP vs NEMA
Are they the same?
Internal
FORMS OF
SEPARATION
• Based from IEC 61439-2
• Protection against contact with live parts
belonging to the adjacent functional units
• Protection against the passage of solid
foreign bodies from one unit of an assembly
to an adjacent unit.
• Note: forms of separation is a guide
Internal
FORMS OF
SEPARATION
• Form 1
• Form 2
• Form 3
• Form 4
Internal
FORMS OF
SEPARATION
• Form 1 – no separation
FORM
• Form 2 – separation of bus-bars from the
functional units
CONSTRUCTION
TYPE
1
2a
• Form 3 – separation of bus-bars,
separation of all functional units from one
another, but not their outgoing terminals
2b
Type 1
Type 2
• Form 4 – separation of bus-bars,
separation of all functional units from one
another including their outgoing terminals
3a
3b
Type 1
Type 2
Internal
FORMS OF
SEPARATION
• Form 1 – no separation
• Form 2 – separation of bus-bars from the
functional units
FORM
CONSTRUCTION
TYPE
4a
Type 1
Type 2
• Form 3 – separation of bus-bars,
separation of all functional units from one
another, but not their outgoing terminals
Type 3
4b
• Form 4 – separation of bus-bars,
separation of all functional units from one
another including their outgoing terminals
Type 4
Type 5
Type 6
Type 7
Internal
FORMS OF
SEPARATION
• Form 1 – no segregation of busbar,
terminals, cables & functional unit
• Advantage:
• Cheap
• Fast fabrication
• Air circulation
• Disadvantage:
• Possible damage to adjacent functional
unit during arc flash
Internal
FORMS OF
SEPARATION
• Form 2a
- Busbars are separated from functional units
only
- Functional units are not separated from
each other and not separated from incoming
or outgoing termination
• Advantage: value engineering
• Disadvantage: Can affect other functional
units during arcflash
Internal
FORMS OF
SEPARATION
• Form 2b – Type 1
- Busbars are separated from functional units
- Separation is thru insulation
Heat Shrinkable Sleeve
1kV – 36kV
PVC Busbar Sleeve
Tagging only
Internal
FORMS OF
SEPARATION
• Form 2b – Type 2
- Busbars/conductor are separated from
functional units via partitions
- Functional units are not separated
Internal
FORMS OF
SEPARATION
• Form 3a
- Busbars are separated from functional units
- Functional units are separated from each
other
- Functional units are separated from
incoming and outgoing terminals
- Incoming and outgoing terminals are not
separated from each other
Internal
FORMS OF
SEPARATION
• Form 3b – Type 1
- Busbars are separated from functional units
- Functional units are separated from each
other
- Terminals for external conductors are
separated from the respective functional
unit and the busbars
- Busbars with insulation cover
`
Internal
FORMS OF
SEPARATION
• Form 3b – Type 2
- Busbars are separated from functional units
- Functional units are separated from each
other
- Terminals for external conductors are
separated from the respective functional
unit and the busbars
- Busbar separation is thru barrier or partition
Internal
FORMS OF
SEPARATION
• Form 4a – Type 1
- Busbars are separated from functional units
- Functional units are separated from each
other
- Separation of terminals for external
conductors from other terminals and from
the busbars
- Busbar is with insulation
Internal
FORMS OF
SEPARATION
• Form 4a – Type 2
- Busbars are separated from functional units
- Functional units are separated from each
other
- Separation of terminals for external
conductors from other terminals and from
the busbars
- Busbar separation is thru barrier or partition
Internal
FORMS OF
SEPARATION
• Form 4a – Type 3
- Busbars are separated from functional units
- Functional units are separated from each
other
- Individual, integral cable glanding facilities
are to be provided for each circuit
Internal
FORMS OF
SEPARATION
• Form 4b – Type 4
- Busbars are separated from functional units
- Functional units are separated from each
other
- Terminals for external conductors from their
own functional unit, other sets of terminals
and from the busbars
Internal
FORMS OF
SEPARATION
• Form 4b – Type 5
- Busbars are separated from functional units
- Functional units are separated from each other
- Terminals for external conductors from their
own functional unit, other sets of terminals and
from the busbars
- Separation of terminals for external conductors
to be achieved by insulated coverings.
Internal
FORMS OF
SEPARATION
• Form 4b – Type 6
- Busbars are separated from functional units
- Functional units are separated from each
other
- Terminals for external conductors from other
terminals and from the busbars
Internal
FORMS OF
SEPARATION
• Form 4b – Type 7
- Busbars are separated from functional units
- Functional units are separated from each
other
- Terminals for external conductors from other
terminals and from the busbars
- Individual, integral cable glanding facilities
are to be provided for each circuit.
Internal
BUSBAR
• Low-impedance conductor to
which several electric circuits
can be separately connected
• Backbone of LVSG
• Main Busbar
• Distribution Busbar
Internal
BUSBAR DESIGN
CONSIDERATIONS
• Material
• Busbar Jointing
• Calculation
Internal
MATERIAL
Conductor material needs the following properties:
• Low electrical and thermal resistance
• High mechanical strength in tension, compression and shear
• High resistance to fatigue failure
• Low electrical resistance of surface films
• Ease of fabrication
• High resistance to corrosion
• Competitive first cost and high eventual recovery value.
Internal
MATERIAL
PROPERTY (@20C)
COPPER
(C101)
ALUMINUM
(1350)
Electrical Conductivity (Annealed)
% IACS
101
61
Electrical Resistance (Annealed)
mΩ mm
17.2
28.3
Temperature Coefficient of Resistivity per K
0.0039
0.004
Thermal Conductivity
W/m-K
397
230
Specific Heat
J/kg-K
385
900
Coefficient of Expansion
per K
17 x 10-6
23 x 10-6
Tensile Strength (Annealed)
N/mm2
200-250
50-60
Tensile Strength (half hard)
N/mm2
260-300
85-100
0.2% Proof Strength (annealed)
N/mm2
50-55
20-30
0.2% Proof Strength (half hard)
N/mm2
170-200
60-65
Elastic Modulus
kN/mm2
116-130
70
kg/m2
8910
2700
°C
1083
660
Density
Melting Point
Internal
MATERIAL
Temperature Effect on Conductivity
– Conductivity varies with temperature
𝑅 = 𝑅20 (1 + 𝛼20βˆ†π‘‡)
Where:
𝑅
− π‘π‘œπ‘π‘π‘’π‘Ÿ π‘π‘œπ‘›π‘‘π‘’π‘π‘‘π‘œπ‘Ÿ π‘Ÿπ‘’π‘ π‘–π‘ π‘‘π‘Žπ‘›π‘π‘’ @ 200°πΆ, Ω
𝑅20 − π‘π‘œπ‘›π‘‘π‘’π‘π‘‘π‘œπ‘Ÿ π‘Ÿπ‘’π‘ π‘–π‘ π‘‘π‘Žπ‘›π‘π‘’ @ 20℃, Ω
𝛼20 − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘π‘œπ‘’π‘“π‘“π‘–π‘π‘–π‘’π‘›π‘‘ of resistance @ 20℃, π‘π‘’π‘Ÿ 𝐾
βˆ†π‘‡ − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘‘π‘–π‘“π‘“π‘’π‘Ÿπ‘’π‘›π‘π‘’, 𝐾
βˆ†π‘‡ = π‘‡π‘˜ − 20
π‘‡π‘˜ − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘‘π‘–π‘“π‘“π‘’π‘Ÿπ‘’π‘›π‘π‘’, 𝐾
Internal
BUSBAR JOINTING
• Jointing Considerations
• Jointing Method
Internal
JOINTING
CONSIDERATION
• Joint resistance
• Streamline effect
• Contact resistance
• Machining busbars
Internal
JOINTING
CONSIDERATION
Sizes of the contact areas
Contact area = 5 x cross section area
Ac = 5 x Ab
Lc = 5 x tb
Ac
Ab
Internal
JOINTING
CONSIDERATION
• Joint resistance – clamped or bolted joint is
made by bringing together two flat surfaces
under controlled (and maintained) pressure
• Streamline effect
𝑅𝑗 = 𝑅𝑠 + 𝑅𝑖
𝑅𝑗 − joint resistance
𝑅𝑠 − spreading resistance
• Contact resistance
𝑅𝑖 − π‘–π‘›π‘‘π‘’π‘Ÿπ‘“π‘Žπ‘π‘’ π‘Ÿπ‘’π‘ π‘–π‘ π‘‘π‘Žπ‘›π‘π‘’
• Machining busbars
Internal
JOINTING
CONSIDERATION
• Joint resistance
• Streamline effect – current flow to
the overlap related to the ratio of
busbar joint overlap & thickness
• Contact resistance
• Machining busbars
Internal
JOINTING
CONSIDERATION
• Joint resistance
𝑅𝑠 π‘Žπ‘
𝑒=
=
𝑅𝑠
𝑅𝑏 πœŒπ‘™
• Streamline effect – current flow to
𝑒 − resistance ratio
the overlap related to the ratio of
𝑅𝑠 − resistance of overlap, μΩ
busbar joint overlap & thickness
𝑅𝑏 − resistance of busbar, μΩ
𝜌 − resistivity of busbar, μΩ
• Contact resistance
π‘Ž − busbar width, π‘šπ‘š
𝑏 − busbar thickness, π‘šπ‘š
• Machining busbars
Internal
JOINTING
CONSIDERATION
• Joint resistance
• Streamline effect
• Contact resistance – the contact
interface between the 2 faces of a
busbar joint consists of a large number
of separate point contacts
• Condition of contact surface
• Contact pressure
Internal
JOINTING
CONSIDERATION
• Condition of contact surface
o dirt on busbar surface prior to
jointing affects conductivity
o busbar surface should be cleaned
from contaminants prior to jointing
o purpose of coating (tin, nickel,
silver) is to prevent re oxidation or
corrosion of busbar
Internal
JOINTING
CONSIDERATION
• Condition of contact surface
o Nickel plating
o a process that involves
depositing a layer of nickel
onto a copper substrate
o this layer provides a protective
barrier that enhances the
durability and resistance of the
copper to corrosion, wear, and
tarnishing
Internal
JOINTING
CONSIDERATION
• Condition of contact surface
o Silver plating
o providing stable contact
resistance and a low maximum
operating temperature that
increase the service life of the
bus joint.
Internal
JOINTING
CONSIDERATION
• Condition of contact surface
o Tin plating
o the most versatile finish for
copper bus bars.
o provides excellent corrosion
resistance for components
susceptible to tarnish under a
wide range of environmental
conditions. electronics.
Internal
JOINTING
CONSIDERATION
• Contact Pressure
𝑇 = 𝐾𝐹𝐷
o The appropriate torque for each
bolt size depends on the bolt
𝑇 − tightening torque (Nm)
material and the maximum
𝐾 − constant, often referred to
as the ‘nut factor
operating temperature expected.
𝐹 − force (kN)
o Contact resistance falls rapidly
with increasing pressure
𝐷 − nominal bolt diameter (mm)
Internal
JOINTING
CONSIDERATION
Nut Factors for Different States
of Lubrication
BOLT LUBRICATION
NUT
FACTOR
DRY
0.20 – 0.22
CONTACT ACID
COMPOUND
0.19 – 0.21
BOUNDARY
LUBRICANT (MO2S)
0.15 – 0.16
Typical Thread Characteristics
Internal
JOINTING
CONSIDERATION
EXAMPLE:
The proof load for a M30 metric bolt grad 8.8 is 337,000N. Calculate torque required to
achieve this tension with a dry bolt with 0% lubrication.
𝑇 = 𝐾𝐹𝐷
𝑇 = (0.2)(337π‘˜π‘)(30mm)
𝑇 = 2022π‘π‘š
Internal
JOINTING
CONSIDERATION
• Joint resistance
• Streamline effect
• Contact resistance
• Machining busbars
o Copper is a soft, “greasy” or “sticky” metal in
terms used in the trade
o shaping is generally carried out dry, but
lubrication is necessary for high-speed
cutting or drilling operations (up to 50 m/mn).
Internal
JOINTING
CONSIDERATION
• Joint resistance
• Streamline effect
• Contact resistance
• Machining busbars
o Cutting
o Punching
𝑙 = 𝐿1 + 𝐿2
o Bending
Internal
BUSBAR
THICKNESS
MINIMUM
BENDING
RADIUS
Upto 10mm
1t
11 – 25mm
1.5t
26 – 50mm
2t
JOINTING METHODS
• Bolted Joints
• Welded Joints
• Soldered Joints
• Clamped Joints
• Riveted Joints
Internal
JOINTING METHODS
• Bolted Joints – formed by overlapping the
bars and bolting through the overlap area
• Welded Joints
• Soldered Joints
• Clamped Joints
• Riveted Joints
Internal
JOINTING METHODS
Bar
Width
mm
Joint
Overlap
mm
Joint
Area
mm2
Number
of Bolts
Coarse
Thread
Bolt
Torque
Nm
Hole Size
mm
Washer
Diameter
mm
Washer
Thickness
mm
16
32
512
2
M6
7.2
7
14
1.8
20
40
800
2
M6
7.2
7
14
1.8
25
60
1500
2
M8
17
10
21
2.0
30
60
1800
2
M8
17
10
21
2.0
40
70
2800
2
M10
28
11.5
24
2.0
50
70
3500
2
M12
45
14
28
2.2
60
60
3600
4
M10
28
11.5
24
2.7
80
80
6400
4
M12
45
14
28
2.2
100
100
1000
5
M12
45
15
28
2.7
120
120
14400
5
M12
45
15
28
2.7
160
160
25600
6
M16
91
20
28
2.7
200
200
40000
8
M16
91
20
28
2.7
Internal
JOINTING METHODS
• Bolted Joints
• Welded Joints – made by butting the ends
of the bars and welding
• Soldered Joints
• Clamped Joints
• Riveted Joints
Internal
JOINTING METHODS
• Bolted Joints
• Welded Joints
• Soldered Joints – rarely used for busbars
unless they are reinforced with bolts or
clamps since heating under short-circuit
conditions can make them both
mechanically and electrically unsound.
Internal
JOINTING METHODS
• Bolted Joints
• Welded Joints
• Soldered Joints
• Clamped Joints – formed by overlapping the
bars and applying an external clamp around
the overlap.
Internal
JOINTING METHODS
• Bolted Joints
• Welded Joints
• Soldered Joints
• Clamped Joints
• Riveted Joints – similar to bolted joints but difficult
to control the contact pressure
Internal
BUSBAR CALCULATION
FACTORS
• Busbar Cross Section
• Arrangement & mounting
• Altitude
• Short circuit resistance & its support
Internal
BUSBAR CALCULATION
FACTORS
• Heat generated by a busbar
• DC: Heat is generated per unit length of a
conductor carrying a direct current, 𝐼 2 𝑅𝑑𝑐
• AC: resistance is increased due to
𝑃 = 𝐼 2 𝑅0 𝑆, W/mm
𝐼 − current, A
𝑅0 − dc resistance per length, Ω/π‘šπ‘š
tendency to flow to outer surface
𝑆 − skin effect
π‘…π‘Žπ‘
𝑆=
𝑅𝑑𝑐
π‘…π‘Žπ‘ − 𝑒𝑓𝑓𝑒𝑐𝑑𝑖𝑣𝑒 π‘Žπ‘ π‘Ÿπ‘’π‘ π‘–π‘ π‘‘π‘Žπ‘›π‘π‘’, Ω
Internal
BUSBAR CALCULATION
FACTORS
𝐼 − current, A
o Flat Bars @ 40°C
A − cross sectional area, π‘šπ‘š2
𝐴0.5 𝑝0.39 πœƒ 0.61
𝐼 = 1.02
[ 1 + π›Όπœƒ 𝜌]0.5
p − conductor perimeter, mm
θ − temperature βˆ† 𝑏𝑒𝑑𝑀𝑒𝑒𝑛 conductor & air, °πΆ
o Hollow Round Bars @ 40°C
α − temperature coefficient, per ℃
𝐴0.5 𝑝0.36 πœƒ 0.61
𝐼 = 1.13
[ 1 + π›Όπœƒ 𝜌]0.5
ρ − resistivity of copper, μΩmm
πΌπ‘Žπ‘ =
o Solid Round Bars @ 40°C
𝐴0.68 πœƒ 0.61
𝐼 = 1.78
[ 1 + π›Όπœƒ 𝜌]0.5
Internal
𝐼𝑑𝑐
π‘…π‘Žπ‘
𝑅𝑑𝑐
BUSBAR CALCULATION
FACTORS
𝐼 − current, A
o Flat Bars @ 50°C
A − cross sectional area, π‘šπ‘š2
𝐼 = 7.73𝐴0.5 𝑝0.39
p − conductor perimeter, mm
o Hollow Round Bars @ 50°C
𝐼 = 8.63𝐴0.5 𝑝0.36
πΌπ‘Žπ‘ =
o Solid Round Bars @ 50°C
𝐼 = 13.6𝐴0.68
Internal
𝐼𝑑𝑐
π‘…π‘Žπ‘
𝑅𝑑𝑐
BUSBAR CALCULATION
FACTORS
• Lamination or Parallel connection
• It is the combination of another busbar in
parallel
• Additional busbar to increase the
ampacity required
• This is due to obstruction to free air
(convection & radiation)
• Recommended spacing = busbar
thickness
Internal
BUSBAR PLY
MULTIPLYING
FACTOR
2
1.8
3
2.5
4
3.2
5
3.9
6
4.4
8
5.5
10
6.5
BUSBAR CALCULATION
FACTORS
A copper busbar @ 50C & 50Hz, with the following dimension: 100 x 5mm, S=1.12
• Determine the DC current
• Determine the AC current
• Determine the AC current if parallel with 3 bars
Internal
BUSBAR CALCULATION
FACTORS
A copper busbar @ 50C & 50Hz, with the following dimension: 100 x 5mm, S=1.12
• Determine the DC current
• Determine the AC current
• Determine the AC current if parallel with 3 bars
Given: copper busbar = 100 x 5mm, 50Hz, @ 50C, S=1.12
Required: Idc, Iac, Iac with 3 // bars
Internal
BUSBAR CALCULATION
FACTORS
Solution:
𝑰 = πŸ•. πŸ•πŸ‘π‘¨πŸŽ.πŸ“ π’‘πŸŽ.πŸ‘πŸ—
πΌπ‘Žπ‘ = 1314.75 π‘₯ 2.5
𝐴 = 100π‘₯5 = 500π‘šπ‘š2
𝑰𝒂𝒄 = πŸ‘, πŸπŸ–πŸ”. πŸ–πŸ–π‘¨ @ πŸ‘π’‘π’π’š 𝒃𝒖𝒔𝒃𝒂𝒓
𝑝 = 2 100 + 5 = 210π‘šπ‘š
𝐼 = 7.73(500)0.5 (210)0.39
𝑰𝒅𝒄 = 𝟏, πŸ‘πŸ—πŸπ‘¨
𝑆 = 1.12 = 1.058
1,391𝐴
πΌπ‘Žπ‘ =
1.058
𝑰𝒂𝒄 = πŸπŸ‘πŸπŸ’. πŸ•πŸ“π‘¨
Internal
BUSBAR CALCULATION
FACTORS
πΌπ‘π‘’π‘ π‘π‘Žπ‘Ÿ = πΌπ‘β„Žπ‘Žπ‘Ÿπ‘‘ π‘₯ π‘˜1 π‘₯ π‘˜2 π‘₯ π‘˜3 π‘₯ π‘˜4 π‘₯ π‘˜5
πΌπ‘π‘’π‘ π‘π‘Žπ‘Ÿ − π‘π‘Žπ‘™π‘π‘’π‘™π‘Žπ‘‘π‘’π‘‘ π‘π‘’π‘ π‘π‘Žπ‘Ÿ π‘Žπ‘šπ‘π‘Žπ‘π‘–π‘‘π‘¦
πΌπ‘β„Žπ‘Žπ‘Ÿπ‘‘ − π‘π‘’π‘Ÿπ‘Ÿπ‘’π‘›π‘‘ π‘£π‘Žπ‘™π‘’π‘’ π‘ π‘‘π‘Žπ‘‘π‘’π‘‘ π‘œπ‘› π‘β„Žπ‘Žπ‘Ÿπ‘‘
π‘˜1 , π‘˜2 , π‘˜3 , π‘˜4 , π‘˜5 − π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
Internal
BUSBAR CALCULATION
FACTORS
π‘˜1 − π‘šπ‘Žπ‘‘π‘’π‘Ÿπ‘–π‘Žπ‘™ π‘π‘œπ‘›π‘‘π‘’π‘π‘‘π‘–π‘£π‘–π‘‘π‘¦ π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜1 = 1, 𝑖𝑓 π‘’π‘›π‘˜π‘›π‘œπ‘€π‘›
π‘˜2 − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜2 – Heat resistance of equipment in
contact with busbars (such as insulators or
current transformers) must be considered
when determining the temperature level
that busbars can reach.
In electricity switch enclosures, busbar
temperature must be under 100°C.
Internal
BUSBAR CALCULATION
FACTORS
π‘˜1 − π‘šπ‘Žπ‘‘π‘’π‘Ÿπ‘–π‘Žπ‘™ π‘π‘œπ‘›π‘‘π‘’π‘π‘‘π‘–π‘£π‘–π‘‘π‘¦ π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜1 = 1, 𝑖𝑓 π‘’π‘›π‘˜π‘›π‘œπ‘€π‘›
π‘˜2 − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜2 – Heat resistance of equipment in
contact with busbars (such as insulators or
current transformers) must be considered
when determining the temperature level
that busbars can reach.
In electricity switch enclosures, busbar
temperature must be under 100°C.
Internal
BUSBAR CALCULATION
FACTORS
π‘˜3 − π‘šπ‘œπ‘’π‘›π‘‘π‘–π‘›π‘” 𝑒𝑓𝑓𝑒𝑐𝑑 π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜3 = 1, 𝑖𝑓 π‘£π‘’π‘Ÿπ‘‘π‘–π‘π‘Žπ‘™ π‘šπ‘œπ‘’π‘›π‘‘
Internal
BUSBAR CALCULATION
FACTORS
π‘˜4 − π‘Žπ‘ π‘ π‘’π‘šπ‘π‘™π‘¦ 𝑒𝑓𝑓𝑒𝑐𝑑 π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜4 = 1, 𝑒𝑠𝑒𝑑 π‘“π‘œπ‘Ÿ π‘’π‘™π‘’π‘π‘‘π‘Ÿπ‘–π‘π‘–π‘‘π‘¦ π‘ π‘€π‘–π‘‘π‘β„Ž π‘’π‘›π‘π‘™π‘œπ‘ π‘’π‘Ÿπ‘’π‘ 
𝑁𝑂𝑇𝐸: π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘–π‘’π‘Ÿ 𝑖𝑠 𝑒𝑠𝑒𝑑 π‘€β„Žπ‘’π‘› π‘‘β„Žπ‘’π‘Ÿπ‘’
𝑖𝑠 π‘›π‘œ π‘œπ‘’π‘‘π‘™π‘’π‘‘ 𝑖𝑛 2π‘š π‘œπ‘› π‘π‘’π‘ π‘π‘Žπ‘Ÿ
𝑏 −β„Ž
π‘˜4 =
π‘Ž2
Internal
BUSBAR CALCULATION
FACTORS
π‘˜4 − π‘Žπ‘ π‘ π‘’π‘šπ‘π‘™π‘¦ 𝑒𝑓𝑓𝑒𝑐𝑑 π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
π‘˜4 = 1, 𝑒𝑠𝑒𝑑 π‘“π‘œπ‘Ÿ π‘’π‘™π‘’π‘π‘‘π‘Ÿπ‘–π‘π‘–π‘‘π‘¦ π‘ π‘€π‘–π‘‘π‘β„Ž π‘’π‘›π‘π‘™π‘œπ‘ π‘’π‘Ÿπ‘’π‘ 
π‘˜4 𝑖𝑓 𝑆 = 10π‘šπ‘š
π‘˜4 𝑖𝑓 𝑆 = 5π‘šπ‘š
Internal
BUSBAR CALCULATION
FACTORS
π‘˜5 − π‘Žπ‘™π‘‘π‘–π‘‘π‘’π‘‘π‘’ 𝑒𝑓𝑓𝑒𝑐𝑑 π‘šπ‘’π‘™π‘‘π‘–π‘π‘™π‘¦π‘–π‘›π‘” π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿ
𝐴𝑠 π‘Žπ‘™π‘‘π‘–π‘‘π‘’π‘‘π‘’ π‘‘π‘’π‘π‘Ÿπ‘’π‘Žπ‘ π‘’π‘ , π‘ π‘œ π‘Žπ‘  π‘Žπ‘–π‘Ÿ 𝑑𝑒𝑛𝑠𝑖𝑑𝑦.
πΆπ‘œπ‘œπ‘™π‘–π‘›π‘” π‘π‘Žπ‘π‘Žπ‘π‘–π‘‘π‘¦ π‘‘π‘’π‘π‘Ÿπ‘’π‘Žπ‘ π‘’π‘ , π‘‘β„Žπ‘’π‘ ,
β„Žπ‘’π‘Žπ‘‘ π‘–π‘›π‘π‘Ÿπ‘’π‘Žπ‘ π‘’π‘ 
Internal
BUSBAR CALCULATION
FACTORS
A copper busbar with the following dimension: 80 x 10mm
• Determine the busbar ampacity
Internal
BUSBAR CALCULATION
FACTORS
A copper busbar with the following dimension: 80 x 10mm
• Determine the busbar ampacity if bare
Given: copper busbar = 2 x 80 x 10mm
Solution:
π‘˜1 = 1, π‘›π‘œ π‘šπ‘Žπ‘‘π‘’π‘Ÿπ‘–π‘Žπ‘™ π‘π‘œπ‘›π‘‘π‘’π‘π‘‘π‘–π‘£π‘–π‘‘π‘¦ π‘π‘Ÿπ‘œπ‘£π‘–π‘‘π‘’π‘‘
πΌπ‘π‘’π‘ π‘π‘Žπ‘Ÿ = πΌπ‘β„Žπ‘Žπ‘Ÿπ‘‘ π‘₯π‘˜1 π‘₯π‘˜2 π‘₯π‘˜3 π‘₯π‘˜4 π‘₯π‘˜5
π‘˜2 = 1, π‘Žπ‘šπ‘π‘–π‘’π‘›π‘‘ π‘‘π‘’π‘šπ‘ π‘œπ‘“ 𝐿𝑉𝑆𝐺 𝑖𝑠 35℃
πΌπ‘π‘’π‘ π‘π‘Žπ‘Ÿ = 2110π‘₯1x1x1x1
π‘˜3 = 1, 𝑠𝑖𝑛𝑐𝑒 π‘£π‘’π‘Ÿπ‘‘π‘–π‘π‘Žπ‘™ π‘šπ‘œπ‘’π‘›π‘‘
πΌπ‘π‘’π‘ π‘π‘Žπ‘Ÿ = 2110𝐴
π‘˜4 = 1, π‘›π‘œ π‘™π‘œπ‘›π‘”π‘’π‘Ÿ π‘‘β„Žπ‘Žπ‘› 2π‘š
π‘˜5 = 1, π‘Žπ‘π‘œπ‘£π‘’ π‘ π‘’π‘Ž 𝑙𝑒𝑣𝑒𝑙
Required: busbar ampacity
Internal
BUSBAR CALCULATION
Simpler means?
Use Rule of Thumb:
• Calculation 1:
2A/mm2
I = 2 xw x t
I = 2A /mm2 x 80mm x 10mm
I = 1600A
I = 1600 x 1.8 = 2880A
• Calculation 2:
Icu = 1.2 x w x t
Ial = 0.8 x w x t
Internal
BUSBAR CALCULATION
FACTORS
• Expansion of main busbar
Length of busbars increase by expanding due to
increase in temperature.
This must be taken into account when busbars
are supported
βˆ†π‘™ = π‘™π‘œ π‘₯ 𝛼 π‘₯ βˆ†π‘‘
βˆ†π‘™ − 𝑒π‘₯π‘Žπ‘π‘Žπ‘›π‘ π‘–π‘œπ‘› π‘™π‘’π‘›π‘”π‘‘β„Ž, π‘š
π‘™π‘œ − π‘–π‘›π‘–π‘‘π‘–π‘Žπ‘™ π‘™π‘’π‘›π‘”π‘‘β„Ž, π‘š
βˆ†π‘‘ − π‘‘π‘’π‘šπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘Ÿπ‘’ π‘‘π‘–π‘“π‘“π‘’π‘Ÿπ‘’π‘›π‘π‘’, 𝐾
𝛼 − π‘π‘œπ‘’π‘“π‘“π‘–π‘π‘–π‘’π‘›π‘‘ π‘œπ‘“ π‘‘β„Žπ‘’π‘Ÿπ‘šπ‘Žπ‘™ 𝑒π‘₯π‘Žπ‘π‘Žπ‘›π‘ π‘–π‘œπ‘›, π‘π‘’π‘Ÿ 𝐾
𝛼 = 0.000017/𝐾
Internal
BUSBAR CALCULATION
FACTORS
• Short Circuit Mechanical Resistance of copper busbar assemblies
πΉπ‘š − π‘“π‘œπ‘Ÿπ‘π‘’π‘  𝑏𝑒𝑑𝑀𝑒𝑒𝑛 π‘šπ‘Žπ‘–π‘› π‘π‘’π‘ π‘π‘Žπ‘Ÿπ‘ 
π‘‘β„Žπ‘’ π‘ π‘Žπ‘šπ‘’ π‘‘π‘–π‘Ÿπ‘’π‘π‘‘π‘–π‘œπ‘›. π‘Žπ‘‘π‘—π‘Žπ‘π‘’π‘›π‘‘ π‘Žπ‘’π‘₯π‘–π‘™π‘–π‘Žπ‘Ÿπ‘¦ 𝑏
π‘‘π‘–π‘Ÿπ‘’π‘π‘‘π‘–π‘œπ‘› π‘“π‘™π‘œπ‘€π‘–π‘›π‘” 𝑖𝑛 π‘Žπ‘‘π‘—π‘Žπ‘π‘’π‘›π‘‘ π‘β„Žπ‘Žπ‘ π‘’π‘ π‘‘π‘–π‘Ÿπ‘’π‘π‘‘π‘–π‘œπ‘› π‘Žπ‘π‘π‘œπ‘Ÿπ‘‘π‘–π‘›π‘” π‘‘π‘œ π‘π‘’π‘Ÿπ‘Ÿπ‘’π‘›π‘‘(π‘β„Žπ‘Žπ‘ π‘’ π‘π‘’π‘ π‘π‘Žπ‘Ÿπ‘ )
Internal
BUSBAR CALCULATION
FACTORS
Calculation of force generated between main busbars
√3 πœ‡π‘œ
2 πΏπ‘š
πΉπ‘š =
π‘₯
π‘₯𝑖𝑝3 π‘₯
2 2πœ‹
π‘Žπ‘š
πΉπ‘š − forces generated between main busbars, N
πœ‡π‘œ − magnetic field constant, H/m
πœ‡π‘œ = 4πœ‹10−7 𝐻/π‘š
𝑖𝑝3 −three phase symmetrical short circuit current peak value, A
πΏπ‘š −length of main busbars between to support points, m
π‘Žπ‘š −effective length between main busbars, m
Internal
BUSBAR CALCULATION
FACTORS
Calculation of force generated between auxiliary busbars
𝑖𝑝3
πœ‡π‘œ
𝐹𝑠 =
π‘₯
2πœ‹
𝒏
2
𝑳𝒔
π‘₯
𝒂𝒔
πΉπ‘š − forces generated between auxiliary busbars, N
πœ‡π‘œ − magnetic field constant, H/m
πœ‡π‘œ = 4πœ‹10−7 𝐻/π‘š
𝑖𝑝3 −three phase symmetrical short circuit current peak value, A
𝐿𝑠 −largest distance between two adjacent intermediate support element used between
main busbars, m
π‘Žπ‘  −effective length between main busbars, m
𝒏 −number of auxiliary busbars creating the main busbar
Internal
BUSBAR CALCULATION
FACTORS
• Busbar assembly whose short circuit mechanic strength will be calculated consists of 2 pcs
of busbars (with a cross-section of 100x10mm) per phase.
• Distance between phase axis is 150mm
• Short circuit current is unknown; however it is known that the transformer supplying the
entire plant has a power of 1000kVA
• Busbar assembly was supported on two lateral planes of each switch cabinets. The widest
switch cabinet has a width of 600mm
• Given:
• Effective short circuit current: 𝑖"π‘˜3 = 25kA
• Busbar = E-Cu F30
• Busbar dimension: 2 x 100 x 10
• 𝑖𝑝3 = n x 𝑖"π‘˜3 = 2.1 x 25kA = 52.5kA
•
•
Lm = 600mm
Ls = 600mm
a = 150mm
πœ‡π‘œ = 4πœ‹10−7 𝐻/π‘š
𝛼 = 1.1
Required: Find the force for the
busbar insulator
• 𝛽 = 0.73
• 𝑅𝑝0,2 π‘šπ‘–π‘› = 250𝑁/π‘šπ‘š2
• 𝑅𝑝0,2 π‘šπ‘Žπ‘₯ = 360𝑁/π‘šπ‘š2
Internal
BUSBAR CALCULATION
FACTORS
Solution:
√3 πœ‡π‘œ
√3 4πœ‹10−7
0.6
2 πΏπ‘š
πΉπ‘š = π‘₯ π‘₯𝑖𝑝3 π‘₯
= π‘₯
π‘₯(52.5k)2 π‘₯
= 1801𝑁
2
2πœ‹
π‘Žπ‘š
2
2πœ‹
0.159
𝑖𝑝3 2 𝑳𝒔
πœ‡π‘œ
4πœ‹10−7
𝐹𝑠 = π‘₯
π‘₯ =
π‘₯
2πœ‹
𝒏
𝒂𝒔
2πœ‹
52.5k 2
2
π‘₯
𝟎.πŸ”
= 1736N
πŸ’πŸ•.πŸ”πŸπ’™πŸπŸŽ−πŸ‘
π‘Žπ‘š =
150
= 159π‘šπ‘š
0.94
1
0.42
1
=
=
π‘Žπ‘ 
20
47.62π‘šπ‘š
πΉπ‘š3 π‘₯ πΏπ‘š
1801 π‘₯ 0.6
πœŽπ‘š = π‘‰πœŽ π‘₯ π‘‰π‘Ÿ π‘₯ 𝛽 π‘₯
= 1π‘₯ 1π‘₯ 0.73 π‘₯
= 29.61π‘₯106 𝑁/π‘š2
−6
8𝑍
8 π‘₯ 3.33π‘₯10
𝑏𝑑 2
0.1π‘₯(0.01)2
𝑍 = 𝑛π‘₯
= 2π‘₯
6
6
−6
3
𝑍 = 3.33π‘₯10 π‘š
𝐹𝑠 π‘₯ 𝐿𝑠
1736 π‘₯ 0.6
πœŽπ‘  = π‘‰πœŽπ‘  π‘₯ π‘‰π‘Ÿπ‘  π‘₯
= 1π‘₯ 1π‘₯
= 39.22π‘₯106 𝑁/π‘š2
−6
16𝑍𝑠
16 π‘₯ 1.66π‘₯10
𝑏𝑑 2 0.1π‘₯(0.01)2
𝑍=
=
6
6
𝑍 = 1.66π‘₯10−6 π‘š3
Internal
BUSBAR CALCULATION
FACTORS
Solution:
6
πœŽπ‘‘π‘œπ‘‘π‘Žπ‘™ = πœŽπ‘š + πœŽπ‘  = 29.61π‘₯10 + 39.22π‘₯10
6
𝑁
6 𝑁
= 68.83π‘₯10 2 π‘œπ‘Ÿ 68.83
π‘š
π‘šπ‘š2
𝐹𝑑 = 𝑉𝐹 π‘₯ π‘‰π‘Ÿ π‘₯ 𝛼 π‘₯ πΉπ‘š = 2.7 π‘₯ 1.1 π‘₯ 1801 = πŸ“πŸ‘πŸ’πŸ—π‘΅
πœŽπ‘‘π‘œπ‘‘π‘Žπ‘™
≤ 3.7
0.8 π‘₯𝑅𝑝0,2 π‘šπ‘Žπ‘₯
68.83
≤ 3.7; 0.24
0.8 π‘₯360
Internal
BUSBAR CALCULATION
FACTORS
Solution:
a.
𝐹𝑑 = πŸ“πŸ‘πŸ’πŸ—π‘΅ , force on the support point
which the busbar can resist short circuit
current w/o bending
b. Insulators need 5349N (535kgf) peak
force in order to resist short circuit
Internal
BUSBAR CALCULATION
FACTORS
Internal
EARTH OR GROUND
BAR
-
a central point for equipment ground
connections
-
a common point where surges flow
-
50% of main busbar rating
Internal
INCOMING &
OUTGOING DEVICES
• INCOMING
• ACB
• MCCB
• ISOLATOR
• FUSE
• OUTGOING
• ACB
• MCCB
• FUSE
• MCB
• MOTOR CB
Internal
AUXILIARY CIRCUITS
– used for controls or monitoring
• MCB
• Relay or contactor
• ATS
• Meter
• Terminal blocks
Internal
HOW TO DESIGN?
• SLD or customer specification
• Do the BOQ
• Determine the sizes & clearances of
functional units
• Determine the cable size, qty & route
• Design the switchgear based from
desired arrangement
Internal
HOW TO DESIGN?
REQUIREMENT
• SLD or customer specification
• Do the BOQ
TYPE
• Determine the sizes & clearances of
functional units
• Determine the cable size, qty & route
• Design the switchgear based from
desired arrangement
Internal
HIMEL OFFER
ITEM
QTY
REFERENCE CODE
TOTAL
HOW TO DESIGN?
• SLD or customer specification
• Do the BOQ
• Determine the sizes & clearances
of functional units
• Determine the cable size, qty & route
• Design the switchgear based from
desired arrangement
Internal
HOW TO DESIGN?
• SLD or customer specification
• Do the BOQ
• Determine the sizes & clearances of
functional units
• Determine the cable size, qty &
route
• Design the switchgear based from
desired arrangement
Internal
HOW TO DESIGN?
• SLD or customer specification
• Do the BOQ
• Determine the sizes & clearances of
functional units
• Determine the cable size, qty & route
• Design the switchgear based from
desired arrangement
Internal
HOW TO DESIGN?
• SLD or customer specification
• Do the BOQ
• Determine the sizes & clearances of
functional units
• Determine the cable size, qty & route
• Design the switchgear based from
desired arrangement
Internal
Q&A
Internal
Low Voltage
Switchgear:
Design &
Calculation
By Jason Sonido – REE
Internal
Thank You
For more information,
visit us on www.himel.com
Scan to contact us
Internal
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