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

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

1 Answer

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 are measured by megger.
First the equipment whose resistance is to be measured is disconnected from supply.
If the machine is a large one, there may be accumulated static charge on the machine.
So we have to discharge it by connecting a wire between the terminals and ground for 15 minutes. Otherwise megger will give wrong reading.
After this we should remove the wire and we have to connect megger terminals (live & earth) to the motor terminal and earth. The rating of the megger should be selected properly. Then rotate the megger at rated speed of 160 rpm and take the readings.
by

Related questions

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

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

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 is the temperature coefficient of insulating materials?

Description : What is the temperature coefficient of insulating materials?

Last Answer : Insulators are negative temperature coefficient materials.

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.

Surface resistance of an insulating material is reduced due to the

Last Answer : Surface resistance of an insulating material is reduced due to the smoky and dirty atmosphere, humidity in the atmosphere.

The electrical diagram shown in the illustration shows _____________. EL-0021 A. 'R1', 'R2', and 'R3' are connected is series B. 'R1', 'R2', and 'R3' are connected in parallel C. the voltages measured across 'R1', 'R2' and 'R3' will be different if 'R1', 'R2' and 'R3' have different values D. the total resistance equals R1 + R2 + R3

Description : The electrical diagram shown in the illustration shows _____________. EL-0021 A. 'R1', 'R2', and 'R3' are connected is series B. 'R1', 'R2', and 'R3' are connected in parallel C. the voltages measured across ... if 'R1', 'R2' and 'R3' have different values D. the total resistance equals R1 + R2 + R3

Last Answer : Answer: B

Which of the following statements is correct for the illustrated circuit? EL-0020 A. 'R1', 'R2', and 'R3' are connected in series. B. 'R1', 'R2', and 'R3' are connected in parallel. C. The voltages measured across 'R1', 'R2', and 'R3' are equal. D. The total resistance equals 1/R1 + 1/R2 + 1/R

Description : Which of the following statements is correct for the illustrated circuit? EL-0020 A. 'R1', 'R2', and 'R3' are connected in series. B. 'R1', 'R2', and 'R3' are connected in parallel. C. The voltages measured across 'R1', 'R2', and 'R3' are equal. D. The total resistance equals 1/R1 + 1/R2 + 1/R

Last Answer : Answer: A

As shown in the illustration if the applied voltage is 12 VDC, the resistance of R1 is 110 ohms, and R2 is 10 kohms what is the voltage measured across R1 EL-0036 A. 11.86 volts B. .131 volts C. 12 volts D. .673 volts

Description : As shown in the illustration if the applied voltage is 12 VDC, the resistance of R1 is 110 ohms, and R2 is 10 kohms what is the voltage measured across R1 EL-0036 A. 11.86 volts B. .131 volts C. 12 volts D. .673 volts

Last Answer : Answer: B

In the illustrated circuit, what is the voltage measured across R1 if the battery is 24 volts, the resistance of R1 is 34 ohms, and the resistance of R2 is 126 ohms? EL-0036 A. 24 volts B. 18.9 volts C. 5.1 volts D. 150 millivolts

Description : In the illustrated circuit, what is the voltage measured across R1 if the battery is 24 volts, the resistance of R1 is 34 ohms, and the resistance of R2 is 126 ohms? EL-0036 A. 24 volts B. 18.9 volts C. 5.1 volts D. 150 millivolts

Last Answer : Answer: C

Conductor resistance may be INDIRECTLY measured by using a/an _____________. A. voltmeter only B. ammeter only C. voltmeter and an ammeter D. ohmmeter only

Description : Conductor resistance may be INDIRECTLY measured by using a/an _____________. A. voltmeter only B. ammeter only C. voltmeter and an ammeter D. ohmmeter only

Last Answer : Answer: C

How grounding resistance could be measured?

Description : How grounding resistance could be measured?

Last Answer : There are few methods, which can give approximately true value. These are described below. a. Fall of potential method: This method is applicable for small grid or sub station where induction effect of ... method is influenced by induction  effect. d. Alternate - 2 of fall of potential method: 

Ammeters and voltmeters used in sinusoidal AC power systems indicate which of the following values of the waveforms measured? A. Peak value B. Root-mean-square value C. Average value D. Maximum value

Description : Ammeters and voltmeters used in sinusoidal AC power systems indicate which of the following values of the waveforms measured? A. Peak value B. Root-mean-square value C. Average value D. Maximum value

Last Answer : Answer: B

Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ________. A. is good for long term preserving since most insulation is organic and contains some amount B. lowers the insulation value and is a common cause of fault grounds in idle machines C. will enhance insulation resistance only if it is fresh water and contains no salt D. reduces the amount of current supplied or drawn by the machine so horsepower is limited

Description : Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ________. A. is good for long term preserving since most insulation is organic and contains some amount B. ... D. reduces the amount of current supplied or drawn by the machine so horsepower is limited

Last Answer : Answer: B

Which insulation is best for insulating root cellar?

Description : Which insulation is best for insulating root cellar?

Last Answer : First, what part of the country are you in? In Utah (where I last saw a root cellar) had a dirt floor, so humidity from the ground could help keep the vegetables humidified. If you are ... but many enter from the outside. http://www.organicgardening.com/learn-and-grow/building-root-cellar-your-home

Does anyone here keep ferrets? I have a question about winter insulating?

Description : Does anyone here keep ferrets? I have a question about winter insulating?

Last Answer : Can you bring them into your home or basement at all? How cold does it get during your winters? Here in Wis I’d need a shed or hen house type structure to thoroughly keep them warm enough. (Personally if I had any they’d be indoors)

What is the effect of heat on insulating material ?

Description : What is the effect of heat on insulating material ?

Last Answer : With increasing temperature, the resistance of almost all solid insulators except Avro decreases. When the temperature drops again, the resistance increases.

Why glass is insulating ?

Description : Why glass is insulating ?

Last Answer : Glass is insulating so that electricity cannot flow through the glass

Who uses screwdriver and a insulating tape?

Description : Who uses screwdriver and a insulating tape?

Last Answer : It is a ELECTRICIAN

What are the benefits of insulating with foam board?

Description : What are the benefits of insulating with foam board?

Last Answer : Foam board is generally used for acoustic insulation. If you're doing something noisy such as playing band instruments in a residential area, the benefit is that the foam will let you do so without violating ... in the rest of the house. Some people put them in basements and practice with a band.

Biological functions of lipids include (A) Source of energy (B) Insulating material (C) Maintenance of cellular integrity (D) All of these

Description : Biological functions of lipids include (A) Source of energy (B) Insulating material (C) Maintenance of cellular integrity (D) All of these

Last Answer : Answer : D

In multi stage compressor, the isothermal compression is achieved by A. Employing intercooler B. By constantly cooling the cylinder C. By running compressor at very slow speed D. By insulating the cylinder

Description : In multi stage compressor, the isothermal compression is achieved by A. Employing intercooler B. By constantly cooling the cylinder C. By running compressor at very slow speed D. By insulating the cylinder

Last Answer : ANSWER : C

Which of the following is the most widely used insulating material for steam carrying pipelines? (A) Ceramic fibre blanket (B) Glass wool and 85% magnesia (C) Vermiculite (D) Slag wool

Description : Which of the following is the most widely used insulating material for steam carrying pipelines? (A) Ceramic fibre blanket (B) Glass wool and 85% magnesia (C) Vermiculite (D) Slag wool

Last Answer : (B) Glass wool and 85% magnesia

The compound of silicon used as insulating material for electric motors/appliances is

Description : The compound of silicon used as insulating material for electric motors/appliances is

Last Answer : silicone.

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.

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

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

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

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

Which of the following is the most widely used heat insulating material for pipelines carrying steam? (A) Tar dolomite bricks followed by asbestos (B) Fireclay refractory followed by aluminium sheet (C) Cotton followed by aluminium foil (D) 85% magnesia cement and glass wool

Description : Which of the following is the most widely used heat insulating material for pipelines carrying steam? (A) Tar dolomite bricks followed by asbestos (B) Fireclay refractory followed by aluminium sheet (C) Cotton followed by aluminium foil (D) 85% magnesia cement and glass wool

Last Answer : (D) 85% magnesia cement and glass wool

What is the major factor that makes coaxial cable less susceptible to noisethan twisted-pair cable? A) inner conductor B) diameterof cable C) outer conductor D) insulating material

Description : What is the major factor that makes coaxial cable less susceptible to noisethan twisted-pair cable? A) inner conductor B) diameterof cable C) outer conductor D) insulating material

Last Answer : outer conductor

The current flowing through an insulating medium is called a) Conduction b) Convection c) Radiation d) Susceptibility

Description : The current flowing through an insulating medium is called a) Conduction b) Convection c) Radiation d) Susceptibility

Last Answer : b) Convection

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)

Dielectric (A) Is an electrical insulating material (B) Of low resistivity is preferred (C) Should have high thermal conductivity (D) Need not defy the corrosive action of chemicals

Description : Dielectric (A) Is an electrical insulating material (B) Of low resistivity is preferred (C) Should have high thermal conductivity (D) Need not defy the corrosive action of chemicals

Last Answer : (A) Is an electrical insulating material

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 low voltage porcelain is mainly used for (A) Switch block (B) Insulating tubes (C) Lamp sockets (D) All of these

Description : The low voltage porcelain is mainly used for (A) Switch block (B) Insulating tubes (C) Lamp sockets (D) All of these

Last Answer : Answer: Option D

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

The disadvantage with paper as insulating material is (a) it is hygroscopic (6) it has high capacitance (c) it is an organic material (d) none of the above

Description : The disadvantage with paper as insulating material is (a) it is hygroscopic (6) it has high capacitance (c) it is an organic material (d) none of the above

Last Answer : (a) it is hygroscopic

The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above

Description : The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above

Last Answer : (d) all of the above