What is the temperature coefficient of insulating materials?

What is the temperature coefficient of insulating materials?
by

1 Answer

Answer :

Insulators are negative temperature coefficient materials.
by

Related questions

A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place (A) The better insulation material should be put just next to pipe (i.e., inside) (B) The better insulating material should be put outside (C) Either of the insulating material could be put on either side (D) Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)

Description : A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place (A) The better insulation material should be put just ... to which insulating material is to be put inside (i.e., just next to the pipe)

Last Answer : (A) The better insulation material should be put just next to pipe (i.e., inside)

What are three types of nonmetallic insulating materials that can be used in a high-temperature environments?

Description : What are three types of nonmetallic insulating materials that can be used in a high-temperature environments?

Last Answer : FEP, extruded polytetrafluoroethylene, and silicone rubber.

State the insulating materials used in motor. Write temperature class and withstand temperature ranges for them.

Description : State the insulating materials used in motor. Write temperature class and withstand temperature ranges for them. 

Last Answer : The insulating materials used in motor are as belows: 1. Cotton, 2. Silk, or paper, 3. Press board, 4. Resins 5. PVC 6. Cellulose-Fiber, 7. Enameled coating, etc  ... Over 180° Mica, porcelain, ceramics, glass quartz, asbestos, treated glass fiber or treated asbestos. etc.

Classify the insulating materials as per operating temperature. Give two examples of each type.

Description : Classify the insulating materials as per operating temperature. Give two examples of each type.

Last Answer : Sr.No.  Insulation Classes  Maximum permissible temperature (0C) Insulating Material 1 Class-Y or O  900 Cotton, silk, paper, press board, wood, cellulose-, PVC, VIR. (Cotton, silk, ... adhesive coating.  7 Class- C  Over 1800 Porcelain, ceramics, glass, quartz. 

The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) (A) K/h0 (B) 2K/h0 (C) h0 /K (D) h0 /2K

Description : The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) (A) K/h0 (B) 2K/h0 (C) h0 /K (D) h0 /2K

Last Answer : (B) 2K/h0

Give reason: Silicones used as insulating materials.

Description : Give reason: Silicones used as insulating materials.

Last Answer : Unlike common organic polymers, silicones do not catch fire. Hence they are used in fire proof suits and insulating material.

Low thermal conductivity of heat insulating materials is due to its (A) Dense structure (B) High proportion of air space (C) High specific heat (D) None of these

Description : Low thermal conductivity of heat insulating materials is due to its (A) Dense structure (B) High proportion of air space (C) High specific heat (D) None of these

Last Answer : (B) High proportion of air space

A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will (A) Increase (B) Decrease (C) Remain unaffected (D) May increase or decrease; depends on the thickness of each layer

Description : A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted ... ) Remain unaffected (D) May increase or decrease; depends on the thickness of each layer

Last Answer : Option C

The breakdown of insulation of the cable can be avoided economically by the use of (a) inter-sheaths (b) insulating materials with different dielectric constants (c) both (a) and (b) (d) none of the above

Description : The breakdown of insulation of the cable can be avoided economically by the use of (a) inter-sheaths (b) insulating materials with different dielectric constants (c) both (a) and (b) (d) none of the above

Last Answer : (c) both (a) and (b)

State two fundamental properties of insulating materials.

Description : State two fundamental properties of insulating materials.

Last Answer : Insulation resistance and dielectric strength.

Give four examples of natural insulating materials.

Description : Give four examples of natural insulating materials.

Last Answer : Ans: Examples of the natural insulating materials are cotton, rubber, wood, mica.

Materials, which provide a path to the magnetic flux, are classified as (A) insulating materials. (B) semi conducting materials. (C) magnetic materials. (D) dielectric materials.

Description : Materials, which provide a path to the magnetic flux, are classified as (A) insulating materials. (B) semi conducting materials. (C) magnetic materials. (D) dielectric materials.

Last Answer : (C) magnetic materials.

Dielectric materials are (A) Insulating materials. (B) Semiconducting materials. (C) Magnetic materials. (D) Ferroelectric materials.

Description : Dielectric materials are (A) Insulating materials. (B) Semiconducting materials. (C) Magnetic materials. (D) Ferroelectric materials.

Last Answer : (A) Insulating materials.

Gold and silver are (A) dielectric materials (B) low resistivity conducting materials. (C) magnetic materials. (D) insulating materials.

Description : Gold and silver are (A) dielectric materials (B) low resistivity conducting materials. (C) magnetic materials. (D) insulating materials.

Last Answer : (B) low resistivity conducting materials.

State various thermal insulating materials. State any two properties of insulating material

Description : State various thermal insulating materials. State any two properties of insulating material

Last Answer : Thermal insulating materials: 1) Asbestos 2) Aluminum Foil 3) Thermocol 4) Saw dust 5) Cork board slabs 6) Foam glass 7) Rock Wool 8) Glass Wool 9) ... . h) Presence of Moisture: with the increase in moisture content, the coefficient of thermal conductivity rises greatly

What are the properties of sound insulating materials?

Description : What are the properties of sound insulating materials?

Last Answer : Properties of sound insulating materials: 1. It should be light in weight 2. Easy to handle and fix 3. It should be resistant to attack termite and insect 4. It should have low density and porous texture 5. It should be fire resistance 6. It should be moisture resistance

State the Properties of thermal insulating materials.

Description : State the Properties of thermal insulating materials.

Last Answer : Properties of thermal insulating materials: 1) Thermal insulating should be bio resistant and dry. 2) Thermal resistant should be chemically resistant and fire proof. 3) Thermal resisting ... in the moisture content in the material, the coefficient of thermal conductivity rises greatly.

Enlist the different sound insulating materials and also state their suitability.

Description : Enlist the different sound insulating materials and also state their suitability. 

Last Answer : Different sound insulating materials: 1) Asbestos , 2) rock wool , 3)glass ,4)silk, 5)Han felt 6) Mineral wool boards, 7)cane fibers. 8) Acoustical plaster boards and tiles 9 ... tiles and acoustic plaster are suitable where absorption of sound required from tile to tile should be uniform.

State situations where sound insulating and damp proofing materials are used.

Description : State situations where sound insulating and damp proofing materials are used. 

Last Answer : Situations where sound insulating materials are used: 1) Glass, mineral wool mats, are used as sound insulators as solid inner layers underneath floors, 2) Wood fibre and asbestos cement slabs are used ... in toilet floors of upper story, so that no dampness will occur in slab below that floor.

State suitability of: (i) Water proofing materials and (ii) Sound insulating materials

Description : State suitability of: (i) Water proofing materials and (ii) Sound insulating materials

Last Answer : i) Suitability of water proofing materials: 1. Concrete, Bricks, Stones, plaster have tendency to get deteriorate, hence leakage of water may occur in slab, beam, columns. Bitumen and tars ... noise. 6) Acoustic tiles and acoustic plaster are suitable where absorption of sound is required.

State any two electrical, mechanical and thermal properties of insulating materials.

Description : State any two electrical, mechanical and thermal properties of insulating materials. 

Last Answer : i) Electrical Properties of insulating material:- 1. It should have high resistance. 2. It should have high breakdown voltage. 3. It should have high dielectric strength. 4. It should have low ... . 4. Ii should have thermal Stability. 5. Co-efficient of thermal expansion should be low.

State failure phenomena observed in insulating material. State four reasons for failure of gaseous and solid dielectric materials.

Description : State failure phenomena observed in insulating material. State four reasons for failure of gaseous and solid dielectric materials. 

Last Answer : Failure phenomena in insulating material means the dielectric property fails :  The dielectric failure mean the dielectric strength of insulating material reduces due to high voltages or high ... 6. Due to poor maintenance of insulating material there may be possibility dielectric failure 

Select insulating materials for following parts : (i) Insulation between heating element and base plate of electric iron. (ii) Insulation used over copper or aluminium conductor used for making coils. (iii) Transformer bushings. (iv) Insulation between transmission line and pole.

Description : Select insulating materials for following parts : (i) Insulation between heating element and base plate of electric iron. (ii) Insulation used over copper or aluminium conductor used for making coils. (iii) Transformer bushings. (iv) Insulation between transmission line and pole.

Last Answer : Parts Insulating Materials  Insulation between heating element and base plate of electric iron. Mica Insulation used over copper or aluminium conductor used for making coils.  ... Transformer bushings Porcelain  Insulation between transmission line and pole. Porcelain

State the type of insulating materials under Class Y and Class B.

Description : State the type of insulating materials under Class Y and Class B.

Last Answer : The type of insulating materials under Class Y : 1. Cotton  2. Silk 3. Paper 4. Rubber 5. PVC The type of insulating materials under Class B: 1. Backelite 2. Impregnated varnish 3. Mica 4. Fiber glass 5. Asbestos 

State properties of insulating materials.

Description : State properties of insulating materials.

Last Answer : (i) Resistivity should be very high. (ii) It should be water resistant. (iii) It should not contain impurities. (iv) It should not be affected chemically and not corroded easily. (v) Its ... It should be mechanically strong (tensile strength should be more). (vii) It should not be porous.

Explain the mechanical properties of insulating materials.

Description : Explain the mechanical properties of insulating materials.

Last Answer : i) Mechanical strength: Mechanical strength depends on temperature and humidity. a) Temperature: High temperature badly affects the mechanical strength of insulating material. While selecting material ... material should have property of easy moulding and machined into required shape and size.

Give classification of insulating materials on the basis of state of material and give one application of each.

Description : Give classification of insulating materials on the basis of state of material and give one application of each.

Last Answer : Classification of Insulating material State of material   Application Solid insulating materials Wood, rubber, plastic, PVC, glass, porcelain, mica, Polypropylene film etc.   ... Switchgears, gas pressures cables, circuit breakers, generator cooling systems and X-ray apparatus

The electric breakdown strength of insulating materials depends on

Description : The electric breakdown strength of insulating materials depends on  (A) Nature of applied voltage (B) lmperfection of dielectric material (C) Pressure, temperature and humidity (D) All or these

Last Answer : The electric breakdown strength of insulating materials depends on  (A) Nature of applied voltage (B) lmperfection of dielectric material (C) Pressure, temperature and humidity (D) All or these

Effect of moisture on the insulating materials is to

Last Answer : Effect of moisture on the insulating materials is to decrease dielectric constant, decrease dielectric strength, decrease insulation resistance, increase dielectric loss.

Insulating materials have the function of?

Description : Insulating materials have the function of?

Last Answer : Insulating materials have the function of preventing an open circuit between the voltage source and the load.

Which of the following statements, concerning the general maintenance of a brushless generator, is correct? A. Paint should be applied to insulating surfaces on an annual basis. B. Alcohol should be used to remove dust and grime from windings. C. High pressure air should be used to blow out carbon dust. D. Accessible generator parts should be wiped with a clean dry rag on a periodic basis.

Description : Which of the following statements, concerning the general maintenance of a brushless generator, is correct? A. Paint should be applied to insulating surfaces on an annual basis. B. Alcohol should be used to ... . D. Accessible generator parts should be wiped with a clean dry rag on a periodic basis.

Last Answer : Answer: D

On electrical generators one of the bearings is isolated from the bedplate. This insulating block should not be painted and must be kept clean to ___________. A. protect operating personnel from shock B. create an isolated ground for the instrumentation C. allow for the expansion of the generator away from the prime mover as it warms up D. eliminate shaft currents to prevent damaging the bearings

Description : On electrical generators one of the bearings is isolated from the bedplate. This insulating block should not be painted and must be kept clean to ___________. A. protect operating personnel from shock ... the prime mover as it warms up D. eliminate shaft currents to prevent damaging the bearings

Last Answer : Answer: D

If the bearings of an electrical generator are failing more frequently than expected and the lubricating oil is sludging then you should ______________. A. check the connections to the output leads B. check the bearing insulating block on one end of the unit C. replace the bearing with a sealed roller type D. replace the thrust bearing of the prime mover

Description : If the bearings of an electrical generator are failing more frequently than expected and the lubricating oil is sludging then you should ______________. A. check the connections to the output leads B. ... replace the bearing with a sealed roller type D. replace the thrust bearing of the prime mover

Last Answer : Answer: B

Routine maintenance of dry-type transformers should include ______________. A. preventing the entrance of water from broken pipe lines steam lines B. keeping protective surfaces and insulating bushings free of dirt and conductive debris C. periodic testing of insulation resistance with a megger D. all of the above

Description : Routine maintenance of dry-type transformers should include ______________. A. preventing the entrance of water from broken pipe lines steam lines B. keeping protective surfaces and insulating bushings free of ... debris C. periodic testing of insulation resistance with a megger D. all of the above

Last Answer : Answer: D

In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine oil for the first four hours of operation C. baking the armature in an oven at a maximum of 95°C for not over 8 hours D. all of the above

Description : In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine ... in an oven at a maximum of 95°C for not over 8 hours D. all of the above

Last Answer : Answer: A

Temporary repairs to an open DC propulsion armature coil can be made by _____________. A. connecting the coil ends directly to a pair of negative brushes B. disconnecting coil ends, insulating each, and short circuiting the two commutator bars C. grounding the coil ends and short circuiting the commutator bar D. removing the sparking brushes

Description : Temporary repairs to an open DC propulsion armature coil can be made by _____________. A. connecting the coil ends directly to a pair of negative brushes B. disconnecting coil ends, insulating ... C. grounding the coil ends and short circuiting the commutator bar D. removing the sparking brushes

Last Answer : Answer: B

Proper storage battery maintenance includes ____________. A. keeping connections tight and casing surfaces clean B. making sure electrolyte level is below the separator plates C. insulating the terminals with naval jelly D. maintaining a high charging rate at all times

Description : Proper storage battery maintenance includes ____________. A. keeping connections tight and casing surfaces clean B. making sure electrolyte level is below the separator plates C. insulating the terminals with naval jelly D. maintaining a high charging rate at all times

Last Answer : Answer: A

Which of the following statements best describes the material known as varnished cambric? A. Felted asbestos sealed with varnish. B. Cotton cloth coated with insulating varnish. C. Rubber insulation coated with a layer of tin. D. Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.

Description : Which of the following statements best describes the material known as varnished cambric? A. Felted asbestos sealed with varnish. B. Cotton cloth coated with insulating varnish. C. Rubber ... Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.

Last Answer : Answer: B

A circuit breaker differs from a fuse in that a circuit breaker _____________. A. melts and must be replaced B. is enclosed in a tube of insulating material with metal ferrules at each end C. gives no visual indication of having opened the circuit D. trips to break the circuit and may be reset

Description : A circuit breaker differs from a fuse in that a circuit breaker _____________. A. melts and must be replaced B. is enclosed in a tube of insulating material with metal ferrules at each end C. gives no visual indication of having opened the circuit D. trips to break the circuit and may be reset

Last Answer : Answer: D

Electrical leads and insulation on a motor should be painted with ____________. A. heat-resisting acrylic B. heat-resisting aluminum C. insulating varnish D. insulating white lead

Description : Electrical leads and insulation on a motor should be painted with ____________. A. heat-resisting acrylic B. heat-resisting aluminum C. insulating varnish D. insulating white lead

Last Answer : Answer: C

What is the Difference Between "Insulating", "Isolating", and "Shielded Winding" Transformers?

Description : What is the Difference Between "Insulating", "Isolating", and "Shielded Winding" Transformers?

Last Answer : Insulating and Isolating transformers are identical. These terms are used to describe the isolation of the primary and secondary windings, or insulation between the two. A shielded winding transformer, ... are connected to each other electrically, are not of the insulating or isolating variety.

What do you understand by tan delta for a insulating material?

Description : What do you understand by tan delta for a insulating material?

Last Answer : Tan delta measurement is done to find the qualities of insulating material. Tan delta is angle between current due to surface leakage or current due to capacitance and the capacitive current. That is Tan δ = Ir / Ic. 

What do you mean by term insulating resistance? How it is measured?

Description : What do you mean by term insulating resistance? How it is measured?

Last Answer : Insulating resistance: insulating resistance is the opposition offered by an insulating material to the flow of current (electrons) through it when an high potential is applied across it. Insulating resistance ... properly. Then rotate the megger at rated speed of 160 rpm and take the readings.

What is good dielectric break down value for insulating oil?

Description : What is good dielectric break down value for insulating oil?

Last Answer : 60 kV.

The existing resistance of a conductor is dependent upon its length, cross-sectional area, _____________. A. temperature and insulation B. material and insulation C. resistive coefficient and material D. material and temperature

Description : The existing resistance of a conductor is dependent upon its length, cross-sectional area, _____________. A. temperature and insulation B. material and insulation C. resistive coefficient and material D. material and temperature

Last Answer : Answer: D

The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Description : The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Last Answer : (C) 35°C

Consider the following four conditions (1 - 4) and select a correct pair of them as adaptations to environment in desert lizards. Conditions: 1. Burrowing in soil to escape high temperature. 2. Losing heat rapidly from the body during high temperature. 3. Bask in sun when temperature is low. 4. Insulating body due to thick fatty dermis. (a) 3, 4 (b) 1, 3 (c) 2, 4 (d) 1, 2

Description : Consider the following four conditions (1 - 4) and select a correct pair of them as adaptations to environment in desert lizards. Conditions: 1. Burrowing in soil to escape high temperature. 2. Losing heat rapidly from the body during ... to thick fatty dermis. (a) 3, 4 (b) 1, 3 (c) 2, 4 (d) 1, 2

Last Answer : (b) 1, 3

Carnot cycle efficiency depends upon  (a) properties of the medium/substance used  (b) condition of engine  (c) working condition  (d) temperature range of operation  (e) effectiveness of insulating material around the engine.

Description : Carnot cycle efficiency depends upon  (a) properties of the medium/substance used  (b) condition of engine  (c) working condition  (d) temperature range of operation  (e) effectiveness of insulating material around the engine.

Last Answer : Answer : d