Friday, November 29, 2013
Clearances & Creepage distances for LV panel boards
Clearances distances
Shortest distance in the air between two live conductors or between live
Conductors and exposed conductive parts.
14 mm for 12 kV impulse voltage
8 mm for 8 kV impulse voltage
5.5 mm for 6 kV impulse voltage
The IEC 60439-1 and IEC 61439-2 standards stipulate the minimum clearances
Required to withstand impulse voltage up to 2000 m above sea level.
Pollution degree 3.
Creepage distances
Shortest distance along an insulated material surface between two live
Conductors or between live conductors and exposed conductive parts.
16 mm for rated insulation voltage 1000 V AC and DC
12.5 mm for rated insulation voltage 750 V AC and DC
8 mm for rated insulation voltage 500 V AC and DC
See IEC 60439-1 and IEC 61439-2 table 16.
Pollution degree 3,
Material group 3a.
MILLIVOLT DROP TEST
The millivolt drop test is generally associated with
testing for weld quality on the armature. It is the
best test for verifying armature weld quality.
The millivolt drop test is the ultimate electrical test
for detecting bad welds. Unfortunately, it is
difficult to make on armatures with large diameter
wire and nearly impossible to make on armatures
with small wires.
The difficulty is breaking through the insulation on
the wire as it exits the tang or commutator bar
contact. The one testing contact, usually a sharp
knife edged probe, from the KOM (Kelvin Ohm
Meter) can cut through small wires and destroy
the armature. Contact with the knife-edge probe
needs to be made on each bar. Since this is such
a difficult test to perform, it is only practical as a
laboratory test.
Various test methods have been developed over
the last twenty years that come close to making
this test. These tests make it possible to test
100% of the armatures. However, none of these
tests are as accurate or repeatable as the Millivolt
Drop Test.
ESW's weld test, which uses techniques that have
been developed over the past 20 years, comes
very close to the Millivolt Drop Test. The
repeatability and speed of the test using a
stationary armature test fixture assures that a
reliable test has been performed.
Saturday, November 9, 2013
The new IEC 61439 standard
The new IEC 61439 standard applies to enclosures
for which the rated voltage is under 1000 V AC
(at frequencies not exceeding 1000 Hz) or 1500 V DC.
The standard defines the design verified ASSEMBLIES
and eliminates completely the categories TTA and PTTA.
In order to conform to the standard, type tests have been
replaced by a design verification which can be carried
out by the three following equivalent and alternative
methods: testing, calculation/measurement or
application of design rules.
The following parts are mentioned and do not have equal
weighting. There is a formal hierarchy. Each part cannot be
used individually:
−− IEC 61439-1 "General rules"
−− IEC 61439-2 "Power switchgear and control gear ASSEMBLIES"
−− IEC 61439-3 "Distribution boards"
−− IEC 61439-4 "ASSEMBLIES for construction sites"
−− IEC 61439-5 "ASSEMBLIES for power distribution"
−− IEC 61439-6 "Busbar trunking systems"
Part 1 is the general rules part and cannot be used alone to
specify an ASSEMBLY.
Part 2 defines the specific requirements of power switchgear
and controlgear ASSEMBLIES (PSC ASSEMBLIES) and must
be used with Part 1. This is the only part that has a double
role, it covers PSC ASS EMBLIES and any ASS EMBLY which
is not covered by any other specific parts.
Parts 3-X are still under preparation but are already mentioned
in Part 1. These could be more than four, as additional
parts may be developed as the need arises.
Summarising:
With the currently used IEC 60439, the rule
is "one part for each type of ASS EMBLY". With the new
IEC 61439 the rule is "two parts for each type of ASSEMBLY".
The compliance of an ASSEMBLY is declared referring
to the specific ASS EMBLY standard (e.g. IEC 61439-2),
and the compliance with the general rules (IEC 61439-1) is
always implicit. The sentence "TTA switchgear according to
IEC 60439-1" is now replaced by "Power switchgear and
controlgear
ASSEMBLIES according to IEC 61439-2, design
verified ASS EMBLY".
The validity of the two standards will overlap until 2014 and
prior to this date, ASSEMBLIES can be manufactured according
to IEC 61439 or IEC 60439.
Copyright by :
ABB The new standard for low-voltage
switchgear and controlgear assEmblies
IEC 60529 First Characteristic Numeral Degrees of Protection - Water
INDOOR
IP X1 Vertical Falling Drops 10 Min. Drip Test Limited Water Inside;
Not on Live Parts
IP X2 15° Vertical Falling Drops 10 min. 15° Drip Test Limited Water Inside;
Not on Live Parts
IP X3 Spraying Water 5 min. 120° Oscillating Tube or
5 min. Partial Spray
Limited Water Inside;
Not on Live Parts
IP X4 Splashing Water 10 min. 360° Oscillating Tube
or 5 Min. Full Spray
Limited Water Inside;
Not on Live Parts
IP X5 Waterjets Fire Hose 3.3 gal. (12.5L)/min Limited Water Inside;
Not on Live Parts
OUTDOOR
IP X6 Powerful Waterjets Fire Hose 26 gal. (100L)/Min. Limited Water Inside;
Not on Live Parts
IP X7 Temporary Submersion at Limited Depth Submerge 3 ft. (1m) – 30 Min. Limited Water Inside;
Not on Live Parts
IP X8 Prolonged Submersion at Limited Depth More Severe Than X7 Customer Agreement Limited Water Inside;
Not on Live Parts
IEC 60529 First Characteristic Numeral Degrees of Protection - Solids
>> IEC 60529 First Characteristic Numeral Degrees of Protection – Solids
Protection Test Method Pass Criteria
INDOOR
IP 1X Incidental Contact & Solid Objects Ø 50 mm – Probe No Penetration
IP 2X Incidental Contact & Solid Objects Ø 12.5 mm – Probe No Penetration
IP 3X Incidental Contact & Solid Objects Ø 2.5 mm – Probe No Penetration
IP 4X Incidental Contact & Solid Objects Ø 1.0 mm – Probe No Penetration
OD
IP 5X Dust Protected Circulating Dust Limited Dust Inside; Not on Live Parts
IP 6X Dust Tight Circulating Dust No Dust Inside
Thursday, October 24, 2013
Methods of explosion protection for electrical equipment
METHODS OF EXPLOSION PROTECTION
Method Type of Protection
Designed to prevent any means of ignition arising Ex e Increased Safety
Ex n or Ex N Non Sparking
Designed to limit the ignition energy of the circuit Ex I Intrinsic Safety
Designed to prevent the flammable mixture reaching Ex m Encapsulation
a means of ignition Ex p Pressurisation
Ex o Oil Immersion
Ex nR or Ex N Restricted Breathing
Designed to prevent any ignition from spreading Ex d Flameproof Enclosure
Ex q Powder Filling
Saturday, October 19, 2013
Minimum terminal capacity for copper protective conductors (PE, PEN)
| CROSS-SECTIONAL AREA OF PHASE CONDUCTORS S | MINIMUM CROSS-SECTIONAL AREA OF THE CORRESPONDING PROTECTIVE CONDUCTOR (PE, PEN) SPA |
| S ≤ 16 | S |
| 16 < S ≤ 35 | 16 |
| 35 < S ≤ 400 | S/2 |
| 400 < S ≤ 800 | 200 |
| 800 < S | S/4 |
| a Current in the neutral may be influenced where there are significant harmonics in the load. | |
| Minimum terminal capacity for copper protective conductors (PE, PEN) | |
Source: IEC 61439-1 2011 Table 5
Saturday, October 12, 2013
Standard-compliant switchgear and controlgear production (Application of IEC 61439)
A new standard. A new opportunity. 3
Contents 4
One standard for all switchgear and controlgear assemblies 6
What has changed under the new standard? 8
What does the new standard mean for you? 10
Rittal – The System.
Complete solutions – Customised for IEC 61439 12
Strength of materials 14
Protection category of enclosures 16
Verification of protective circuit function 18
Insulating properties 20
Calculation of temperature rise 22
Tested busbar technology 24
The system for the standard 26
Preparation of the design verification 28
I. The design verification 29
II. Individual verifications and verification methods 31
III. Information included in the design verification 32
IV. Sample design verification 44
V. Verification of temperature rise using calculations 48
VI. Verification of short-circuit withstand strength 66
VII. Verification records of individual
switchgear and controlgear assemblies 70
VIII. The routine verification 73
IX. Complete verification of a switchgear and
controlgear assembly 78
X. Assembly cover sheet and design verification form 80
Copyright: c 2013 Rittal GmbH & Co. KG
DOWNLOAD :
http://www.rittal.com/belgium/downloads/brochures/eng/IEC61439_compliant_switchgear_controlgear_production.pdf
Guide to migration from IEC 60439 to IEC 61439 (XL3 Confugurable Assemblies IEC 60439 >>> IEC 61439)
This document only deals with distribution enclosures for advanced users (authorised persons), i.e. parts 1 and 2 of the new standard. Part 3 of standard IEC 61439 discusses DBO (Distribution Boards intended to be operated by Ordinary persons) only up to 250 A. One of the new features of this standard is that the table in appendix D (checking the design) covered laterin this document does not apply in 61439-3.
In addition in its new version, standard 61439-3 takes account of domestic normative references.
DOWNLOAD :
http://www.export.legrand.com/files/fck/pdf-EN/EXB12074_GUIDE_TABLEAUTIERS_EN.pdf
Explanations on the concepts of IEC21439 (Fit for the future with Siemens SIVACON)
Explanations on the concepts of IEC21439 (Fit for the future with Siemens SIVACON)
DOWNLOAD :
Saturday, October 5, 2013
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