Low voltage power distribution & electrical installation technology

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A hipot tester

A hipot tester is an electronic device used to verify the electrical insulation in a device or other wired assembly that could subject someone to a shock if it failed. It generally consists of:

 

1.            A source of high voltage,

2.            A current meter,

3.            A switching matrix used to connect the high voltage source and the current meter to all of the contact points in a cable.

 

Hipot testers may also have a microcontroller and a display to automate the testing process and display the testing results.

A hipot tester can be very similar to a cable tester and often the two are combined into a single device.

In a typical wired assembly a hipot test should connect all circuits in common to ground. Then, one by one the tester will disconnect a given circuit from ground and connect that circuit to high voltage . The current that flows is monitored to verify that it is low enough.

 

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.

 

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

 

Minimum terminal capacity for copper protective conductors (PE, PEN)

CROSS-SECTIONAL AREA OF PHASE CONDUCTORS S MM2	MINIMUM CROSS-SECTIONAL AREA OF THE CORRESPONDING PROTECTIVE CONDUCTOR (PE, PEN) SPA MM2
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

Electrical Installation Calculations Advanced

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http://www.debian.org.ve/varios/libros/Electrical%20Installation%20Calculations%20Advanced,%207th%20Edition%20-%20(Malestrom).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.

 

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http://www.export.legrand.com/files/fck/pdf-EN/EXB12074_GUIDE_TABLEAUTIERS_EN.pdf