low voltage D presentation_LVD presentation.pdf

1
Design and Operation of Low Voltage Switchboard

2
2
Design of Low
Voltage
Switchboard

3
Introduction to
International Standards

4
Switchgear &
controlgear:
IEC 60947-x
IEC Standards:
international references
Busbar trunking:
IEC 60439-2
IEC61439 Standard
Switchboard:
Old: IEC 60439-1
New: IEC 61439-1&2
LV electrical
Installations:
IEC 60364
& local
standards

5
Why an ASSEMBLY standard IEC61439?
Regarding ASSEMBLIES,
safety of persons and property, and availability of electrical power depends on:
> Designing the overall “system” according to the relevant standards
> Controlling various interactions
> Protecting persons against any hazards
due to the ASSEMBLIES themselves
> Providing operating, maintenance
and modification capabilities
IEC61439-1&2 Standard

6
Evolutions of the ASSEMBLY Standard
From IEC 60439-1 to IEC 61439-1&2
Evolutions of the ASSEMBLY Standard
From IEC 60439-1 to IEC 61439-1&2

7
Why a new standard ?
> 80% of the ASSEMBLIES worldwide do not comply with the standard
> Requirements not always clear
> Role of Switchboard System manufacturer and Panel Builder not clear enough
> A Partially Type Tested ASSEMBLY (PTTA) concept abused and misused

8
Main Changes
> Recognition of Original Manufacturer (Switchboard System
manufacturer) and ASSEMBLY Manufacturer (Panel Builder)
> PTTA/TTA concepts replaced with (tested) ASSEMBLY
> Many clarified & reinforced requirements

9
Clear definitions of roles
> ASSEMBLY Manufacturer (Panel Builder)
> Takes the responsibility for the final Assembly
> Carries out routine verifications
> Original Manufacturer (System manufacturer)
> Carries out the original design
> Carries out the design verifications that can be certified
through a certification body (ASEFA, ASTA, KEMA,…)
> ASSEMBLY System
> Full range of mechanical & electrical components (functional
units, switching devices, enclosures…) designed by the
Original Manufacturer to be assembled according to his
instructions
> Specifier (design office, End user,…)
> Specifies or selects the ASSEMBLY
Original
Manufacturer
Assembly
Manufacturer
(Panel Builder)
Specifier
Project Specification
Tested assembly
User
Certification
body
Assembly
system

10
Elimination of TTA and PTTA concepts
Type Tested Assemblies
Partially Type Tested Assemblies
Tested
ASSEMBLIES
●Design verifications
● Mainly type-tests
● Or possibility for only some of the verifications under
clear and strict conditions to do
● Comparison with a tested reference design
(Design Rules)
● Calculations including safety margins
●Routine verifications
● Same as TTA in 10 items instead of 3
●TTA:
●7 type tests on the design
● 3 routine tests on the realization of
each panel
●PTTA
● Calculations not clearly defined to
justify not to do some type-tests
● 3 same routine tests

12
Confidential Property of Schneider Electric
• Main Compartments
• Forms of separation
• Cable connection points
• Access
LV switchboard
assembly

13
Main Compartments

14
IK degree of protection
• International standard IEC
62262 deﬁnes an IK protection
code as the ability of enclosures
to resist external mechanical
impacts on their entire surface.
•Each code represents a value
of the impact energy for a
weight dropped from a height h

15
IP degree of protection

16
Electrical continuity
There are three techniques for
fastening
an earthing wire or braid on a
painted part:
- screw + contact washer,
- insert,
- welded stud.
Always place a contact washer
between
the earthing wire lug and the
painted part

17
Electrical continuity

18
Power bus-bar

19
Power busbar

20
Power busbar

21
Power busbar
The order of the busbars is usually N, L1,L2 and L3:
- from the front to the rear of the switchboard,
- from the left to the right of the switchboard.
This order is not imposed by the standard.
It is recommended for the following reasons:
- safety,
- ease of connection of switchgear,
- easier access to the Neutral bar.
At any event, follow the order recommended
in the technical guides. Whatever the order chosen, the
bars must be marked.

22
Power busbar

23
Clearance distance
IEC 61439-1 standard defines the
requirements applicable to clearances
inside a switchboard. These requirements
are based on the principles of IEC 60664-1
standard and enable the coordination of
clearance inside the switchboard.
Clearance is the shortest distance in the air:
- between two live conductors,
- between a live conductor and
the ground.

24
Creepage distance
The creepage distance is the shortest
distance along the surface of an insulation
between:
- two live conductors,
- between a live conductor and
the bounding surface.

25
Partitioning a switchboard

26

27

28

30
Current transformer connection

31
General

33
> Normal service conditions
 Ambient air temperature
➢for indoor installations
➢for outdoor installations
 Atmospheric conditions
➢ for indoor installations
➢ for outdoor installations
➢ Pollution degree
 Altitude
Maximum altitude over sea level.
Service Conditions

34
> Normal service conditions
 Ambient air temperature
➢ Ambient air temperature for indoor installations:
Tambient ≤ +40 °C
Taverage ≤ +35 °C over 24 hrs period.
Tambient lower = –5 °C.
➢ Ambient air temperature for outdoor installations:
Tambient ≤ +40 °C
Taverage ≤ +35 °C over 24 hrs period.
The lower limit of the ambient air temperature is:
• –25 °C in a temperate climate, and
• –50 °C in an icy climate
Service conditions

35
> Normal service conditions (continue):
 Atmospheric conditions
➢ for indoor installations
Humidity ≤ 50 % at Tmax = +40 °C,
➢ for outdoor installations
Humidity ≤ 100 % at Tmax = +25 °C.
➢ Pollution degree:
There are four Pollution degrees (1 .. To 4), industrial assemblies are generally of pollution degree 3
environment.
Service conditions

36
> Normal service conditions (continue):
 Altitude
- The altitude does not exceed 2000 m.
- High altitudes have reduction impact on dielectric strength and on the
cooling effect of air.
Service conditions

37
Example of current deration due to temperature around
Masterpact air circuit breaker for each connection type
Service conditions

38
Example of dielectric and current deration due to altitude for Masterpact air circuit breaker
Service conditions

39
Thermal Management of Switchboards

41
Calculation of the power dissipated by
devices in the incoming cubicle

42
Once the dissipated power of the devices has been determined and the enclosure with its IP selected,
transfer the results (sum of the dissipated power and width of the device zone) to the chart corresponding
to the enclosure IP.
For the given example, the heat rise is 22 °C at mid-
height in the enclosure.
The internal temperature
= external temperature + heat rise
= 35 °C + 22 °C = 57 °C
57 °C < 60 °C stipulated by the standard, i.e. the
result is acceptable for an IP30 cubicle.

low voltage D presentation_LVD presentation.pdf

More Related Content

Similar to low voltage D presentation_LVD presentation.pdf

Recently uploaded

low voltage D presentation_LVD presentation.pdf