Download - Insulation Material for Arc Furnaces
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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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