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Introducing

The Insulating Materialfor Arc Furnaces

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Insulation material for arc furnacesconsists of several

layers ofMUSCOVITE (A colorless or pale

brown mica with potassium) MICA PAPERimpregnated with silicone binder.

Composition

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What Is MICA?

Any of various minerals consisting of

hydrous silicates ofaluminum or

potassium etc. that crystallize in forms

that allow perfect cleavage into very thin

leaves; used as dielectrics because of theirresistance to electricity.

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What Is MICA?

Any of various minerals consisting ofhydrous silicates ofaluminum

or potassium etc. that crystallize in forms that allow perfect cleavage

into very thin leaves; used as dielectrics because of their resistance to

electricity.

MICA has exceptional physical properties:- High temperature resistance,- Non-flammability,- High dielectric strength,- High compressive strength and high modulus of elasticity,

- Low water absorption,- Resistance to most chemicals and Mineral oil products

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Applications Insulation of electrode arm and

holder in arc and ladle furnaces.

Applications requiring high voltage

resistance at high temperatures.

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PHYSICAL PROPERTIESDescriptions UNIT VALUES

Thickness range Mm > 2 to 100

Thickness tolerance

:- Up to 5mm

:- Above 5 mm

10%

5%

Density Gms/cc 2.2 to 2.5

Mica Content % 90 2

Water absorption after

24 hour immersion% < 0. 5

Weight Loss at

550 0C / 4 hours% < 2.0

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THERMAL PROPERTIES

Descriptions UNIT VALUES

Continuous Operating Temperature 0 C > 500 #

Thermal Conductivity W / m 0K 0.20 min

Thermal Expansion parallel to the laminate cm / cm0 C 4.7 x 10-5 min

Specific Heat J / kg 0C > 850

#Application parameters such as pressure and clamping , the rate of increase /decrease of temperature , etc may have a significant impact on the continuousoperating temperature it can withstand .

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ELECTRICAL PROPERTIES

Descriptions UNIT VALUES

Dielectric Strength Kv / mm > 20

Arc Resistance Seconds > 300

Surface Resistivity Ohms > 1013

Volume Resistivity Ohms-cm > 1013

Dielectric Constant 3.8 min

Comparative Tracking Index Volts > 600

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MECHANICAL PROPERTIESDescriptions UNIT VALUES

Tensile Strength N/ sq.mm > 100

Impact Strength kg- cm M-10.5 X- 10.3

Compressive Strength N/ sq.mm > 300

Machinability

Very good by sanding, milling or

drilling.

HSS or tungsten carbide tools should be used

because of abrasiveness of mica.

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1. CLEAN INSULATION THOROUGHLY

2. INSPECT THE INSULATION. THERE SHOULD NOT BE ANY PHYSICALDAMAGES. REPLACE IF ANY FAULTY PART IS FOUND.

3. CHECK THE INSULATION RESISTANCE VALUES OF THE INSULATION.THE INSULATION VALUES TO BE CHECKED BETWEEN INSULATED PART &LIVE PART.

4. THE TEST VOLTAGE HAS TO BE > (2 x WORKING VOLTAGE +1000V) ANDMORE THAN 3000V. THE MEASURED RESISTANCE HAS TO BE > 3.8 M. THETEST DURATION HAS TO BE 1MIN.

Preventive Measures

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THANK YOU