Presentation IEC Rey-An Moreno

8/17/2019 Presentation IEC Rey-An Moreno

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BY: REYNALDO A. MORENO


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• To gather and protect the control and protectivedevices together with electrical and mechanical

connections against external influences.• To inform the end-user on the state of his

installation.• To protect the switchboard user against the main

risk of accidents (direct contact protection,indirect contact protection and fire risk).

• To evolve with the activity

What is a switchboard used for ?


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The LV electrical switchboard has to be safe

and available

• It is a question of balance between:

–

the needs of safety and availability – the constraints of reliability and maintenability of

the installation.Safety

Maintenability

Reliability Availability


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Ingress protection of enclosures


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Power Distribution System

• The most common IT-system• Limited earth fault current – depending on capacitance in the cabling system• Alarm in case of an earth fault• Ideal for emergency power and important consumers with need for continuous

operation• To be used in UPS-systems

Isolated IT-system


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• The miniature circuit breaker with integrated earth fault tripping is

functioning very well in a fully insulated IT-system!

Isolated IT-system (230 V)


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• Earth fault current calculated to maximum 100 A

• Consumers will be tripped in case of an earth fault

Impedance earthed IT-system


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• Two voltage levels in one system!

• 400/230 V are the most common voltages

• Separate N- and PE-conductors

• Consumers will be tripped in case of an earth fault

• EMC Performance - Excellent

Directly earthed TN-S system


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Signal Classes

• Class 1 - Mains power lines, power circuits with ahigh di/dt, switch-mode converters, power regulation

• Class 2 - Relay contacts.• Class 3 - Digital circuits (HF switching).• Class 4 - Analogue input/output circuits (low-level

measurements, active sensor supply circuits)


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Protective Sheaths


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Routing of Cables


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Routing of Cables


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Routing of Cables

• Spare cable conductors shall either be terminated orinsulated.


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• Power and low level apparatus shall be physically separated andcables segregation and distances between power and sensitivecables shall also be respected as shown on the figure:


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Power Circuits


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Screening of horizontally installed busbars


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Termination


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Conductor Ends (Termination)


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Conductor Ends (Termination)


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Earthing Connections and Conductors

Minimum cross-section of Earthing conductors

Arrangement of earthconductor

Cross-section Q ofassociated currentcarrying conductor(one phase or pole)(mm2)

Minimum cross-section of earthconductor

2. Uninsulated earthconductor in cable for fixedinstallation, being laid underthe cable's lead sheath,armour or copper braid andin metal-to-metal contactwith this.

Q ≤ 2.5 1 mm2

2.5 < Q ≤ 6 1.5 mm2

6 < Q Not permitted

3. Separately installed earthconductor for fixedinstallation

Q < 2.5 Same as current-carrying conductorsubject to minimum 1.5 mm2 forstranded earthing connection or 2.5mm2 for unstranded earthingconnection


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Cabinet Cabling


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Cabinet Cabling


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Enclosure


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Arrangement of Earth Bus-bar

• IE Bar should be isolated from the panel


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Arrangement of Earth Bus-bar

IEC 61892-6 (2007):4.1.3 quotes:“Earth bars, when provided, shall

be located in front of equipmentand junction boxes to allow foreasy access for usage, inspectionand maintenance. All earth barsand terminals shall be visible andpossible to be checked also after

termination of cables.”


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Arrangement of Earth Bus-bar for MCC

Install the complete cable rightup to the level of the

actual starter, and terminate thebraiding and/or earthconductor to the vertical subearth bar at this level !


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Earth Terminations

IEC 61892-6 (2007):4.1.3 quotes:“Separate connections shall beused for each individual earthconductor.”


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Equipment Protective Earthing

• Suitable star washers and conductor terminals shallbe used, so that a reliable contact is ensured.


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Equipment Protective Earthing

• The earthing of the cable itself may be carried out by fixing thecable to the hull constructions, or to parts that are welded or

riveted to the hull constructions (metal to metal without paint orcoating), by corrosion resistant clamps or metal clips.


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Marking and Nameplate


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Clearance and Creepage Distances

Clearance Clearance is the shortest distance between two conductive parts measured through air.Creepage Creepage is the shortest distance between two conductive parts measured along a surface.


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“Type tested assemblies” and “Partly type tested assemblies”

a) Electrical low voltage assemblies constructed and tested in accordance withIEC 60092-302, item 7.1.2.101

(referring to IEC 61439-1) are accepted as long as the following conditionsare met:— minimum clearance distance shall be 8 mm, minimum creepage distanceshall be 16 mm— the assembly has been type tested with impulse voltage test in accordancewith IEC 61439-1

— maximum operating temperature of busbars shall be documented to beacceptable with respect to fixingmaterials and internal temperature by a full current type test— maximum temperature rise at termination points for external cables shallbe 60ºC — such assemblies shall not be installed in machinery space category “A”.


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HAZARDOUS AREAS

• Zone 0 – Area in which an explosive gas atmosphere is presentcontinuously or for long periods.

– Certified safe for Intrinsic safety Ex-ia

• Zone 1 – Area in which an explosive gas atmosphere is likely tooccur in normal operation.

• Zone 2 – Area in which an explosive gas atmosphere is not likelyto occur in normal operation and, if it does occur, islikely to do so infrequently and will exist for a shortperiod only.

– certified safe for Zone 1 and Zone 2 application.—Ex-n standard

—Minimum of IP45


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Ex Protection According to Zones

Zone 2 Zone 1 Zone 0Ex d (flameproof) Yes Yes No

Ex e (increased safety) Yes Yes No

Ex i (intrinsic safe) Yes Yes Yes

Ex p (pressurised) Yes Yes No

Ex n Yes No No

Ex s (special protection) Yes Yes Yes

Ex m (moulded) Yes Yes No

Ex q Yes Yes No

Ex o Yes Yes No


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HAZARDOUS AREAS


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HAZARDOUS AREAS


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HAZARDOUS AREAS

• Ex-i circuits

– All intrinsic safe circuits shall have a safety barrier in form of a zener

barrier or galvanic isolation certified safe for the application in front of thecircuit part going into hazardous areas.

– A circuit in which no spark or any thermal effect produced is capable ofcausing ignition of a given explosive atmosphere


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HAZARDOUS AREAS

• Ex-i circuits

– All intrinsic safe circuits shall have a safety barrier in form of a zener

barrier or galvanic isolation certified safe for the application in front of thecircuit part going into hazardous areas.

• Exi barrier and circuit(s)

must be sufficiently separatedfrom other circuits


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Corresponding Values for NEMA-Type and IP-rating


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Cable types, Cabling and Termination

• All cables installed in hazardous areas shall have an outer non-metallicimpervious sheath.

•

Power and signal cables shall have a metallic braiding or armourbetween conductors and the non-metallic impervious sheath in thefollowing zones and areas:

— zone 0

— zone 1


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The tests of standard IEC 60439-1

There are two type of tests:

• 7 type tests are performed by the manufacturer on one or severalconfigurations: – n°1 temperature rise limits – n°2 dielectric properties – n°3 short-circuit withstand – n°4 protective circuit effectiveness –

n°5 clearances and creepage distances

– n°6 mechanical operation – n°7 degree of protection.

• 3 routine tests are performed by the panelbuilder on each particularswitchboard:

– n°8 general inspection – n°9 insulation/dielectric test – n°10 protection measures.


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Presentation IEC Rey-An Moreno

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