What you mean by dielectric absorption test?

What you mean by dielectric absorption test?
by

1 Answer

Answer :

Whenever we apply a potential from the megger to test the IR value, initially the needle of the megger will go to low value of the resistance. This is due the capacitance effect of the insulation material and after some seconds the needle will start moving towards the higher value. Because in the insulating material there is strain on the molecules when the potential is applied. Polarization of the molecules occurs and they form a Di – pole. The negative charges are attracted to positive terminal and positive charges are attracted to negative terminal. So there is a strain on the insulation molecules and they align themselves parallel. This aligning may take more time. This test is done to know the condition of insulating material.

image  

If the insulation is good the graph is as shown as B and if there is dirt, moisture the graph will flatten early as shown in A. After the test terminals to be discharged so that molecules may return to their unstressed state. 

by

Related questions

When a megohmmeter is used to test the insulation of a large motor, the initial dip of the pointer toward 'zero' is caused by ____________. A. good insulation B. the capacitance of the windings C. the leakage of the current along the surface of dirty insulation D. the dielectric-absorption effect of the insulation

Description : When a megohmmeter is used to test the insulation of a large motor, the initial dip of the pointer toward 'zero' is caused by ____________. A. good insulation B. the capacitance of the ... of the current along the surface of dirty insulation D. the dielectric-absorption effect of the insulation

Last Answer : Answer: B

When using a megohmmeter to test the dielectric strength of wire insulation, a continuous series of slight downscale kicks by the pointer is result of ____________. A. good insulation B. the leakage of current along the surface of dirty insulation C. the capacitance of the windings D. the dielectric-absorption effect of the insulation

Description : When using a megohmmeter to test the dielectric strength of wire insulation, a continuous series of slight downscale kicks by the pointer is result of ____________. A. good insulation B. the ... dirty insulation C. the capacitance of the windings D. the dielectric-absorption effect of the insulation

Last Answer : Answer: B

When a megohmmeter is used to test the dielectric strength of wire insulation, the initial dip of the pointer toward 'zero' is caused by _____________. A. good insulation B. the leakage of current along the surface of dirty insulation C. the capacitance of the circuit D. the dielectric absorption effect of the insulation

Description : When a megohmmeter is used to test the dielectric strength of wire insulation, the initial dip of the pointer toward 'zero' is caused by _____________. A. good insulation B. the leakage of ... of dirty insulation C. the capacitance of the circuit D. the dielectric absorption effect of the insulation

Last Answer : Answer: C

When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the leakage of current along the surface of dirty insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation

Description : When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the ... insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation

Last Answer : Answer: D

What is dielectric test of a circuit breaker?

Description : What is dielectric test of a circuit breaker?

Last Answer : It consists of overvoltage withstand test of power frequency lightning and impulse voltages.Testa are done for both internal and external insulation with switch in both open and closed conditions.

Choose the best definition of dielectric loss. a) Absorption of electric energy by dielectric in an AC field b) Dissipation of electric energy by dielectric in a static field c) Dissipation of heat by dielectric d) Product of loss tangent and relative permittivity

Description : Choose the best definition of dielectric loss. a) Absorption of electric energy by dielectric in an AC field b) Dissipation of electric energy by dielectric in a static field c) Dissipation of heat by dielectric d) Product of loss tangent and relative permittivity

Last Answer : a) Absorption of electric energy by dielectric in an AC field

State the methods used to measure insulation resistance and explain Dielectric Absorption method.

Description : State the methods used to measure insulation resistance and explain Dielectric Absorption method.

Last Answer : There are three types of tests for measuring insulation resistance:  1. Spot test reading or Short Time test  2.Time-resistance test or Dielectric absorption test or Testing methods based on the PI & DAR  3. ... and if value of PI is less than 2 and value of DAR is less than 1.25

Emulsifier protection is associated with: a) Grounding protection b) Dielectric strength protection of cables and conductors c) Lightning protection d) Fire protection

Description : Emulsifier protection is associated with: a) Grounding protection b) Dielectric strength protection of cables and conductors c) Lightning protection d) Fire protection

Last Answer : Ans: D

The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength of the insulation B. the paint dust is composed of abrasive and semi-conducting materials which impair insulation C. paint dust buildup has a tendency to cause corrosion D. phase windings frequently become isolated from each other due to dust interference at the terminals

Description : The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength ... phase windings frequently become isolated from each other due to dust interference at the terminals

Last Answer : Answer: B

Which of the listed conditions could indicate the need for cleaning electrical insulation? A. Low ambient temperature B. Low operating temperature C. High dielectric strength D. Low megger readings

Description : Which of the listed conditions could indicate the need for cleaning electrical insulation? A. Low ambient temperature B. Low operating temperature C. High dielectric strength D. Low megger readings

Last Answer : Answer: D

The 'dielectric constant' of dry air or a vacuum is _______. A. 1 B. 10 C. 100 D. 1000

Description : The 'dielectric constant' of dry air or a vacuum is _______. A. 1 B. 10 C. 100 D. 1000

Last Answer : Answer: A

The 'dielectric constant' is a numerical value indicating the effectiveness of a dielectric material in comparison to that of a standard, which is _______________. A. paper or cloth B. glass or mica C. plastic or Teflon D. dry air or a vacuum

Description : The 'dielectric constant' is a numerical value indicating the effectiveness of a dielectric material in comparison to that of a standard, which is _______________. A. paper or cloth B. glass or mica C. plastic or Teflon D. dry air or a vacuum

Last Answer : Answer: D

The dielectric strength of a vacuum or dry air is approximately ________________. A. 450 volts/inch B. 1000 volts/inch C. 20-kv/inch D. 50-kv/inch

Description : The dielectric strength of a vacuum or dry air is approximately ________________. A. 450 volts/inch B. 1000 volts/inch C. 20-kv/inch D. 50-kv/inch

Last Answer : Answer: C

A 'dielectric' is a/an ________________. A. electrical insulator B. current flow C. good conductor D. semiconductor material

Description : A 'dielectric' is a/an ________________. A. electrical insulator B. current flow C. good conductor D. semiconductor material

Last Answer : Answer: A

A megohmmeter is used to measure _____________. A. voltage B. dielectric strength C. current D. power

Description : A megohmmeter is used to measure _____________. A. voltage B. dielectric strength C. current D. power

Last Answer : Answer: B

The force that causes free electrons to move in a conductor as electric current flow is called a/an _____________. A. resistant force B. electromotive force C. inductive force D. dielectric force

Description : The force that causes free electrons to move in a conductor as electric current flow is called a/an _____________. A. resistant force B. electromotive force C. inductive force D. dielectric force

Last Answer : Answer: B

Which of the following statements about copper wire sized by the AWG rating is correct? A. Number 12 AWG wire has a higher current rating than number 10 AWG wire. B. Number 10 AWG wire has a higher dielectric strength than number 12 AWG wire. C. Number 12 AWG wire is larger than Number 10 AWG wire. D. Number 12 AWG wire at 25°C has more resistance per 1000 feet than No. 10 AWG wire at 25°C.

Description : Which of the following statements about copper wire sized by the AWG rating is correct? A. Number 12 AWG wire has a higher current rating than number 10 AWG wire. B. Number 10 AWG wire has a higher ... Number 12 AWG wire at 25°C has more resistance per 1000 feet than No. 10 AWG wire at 25°C.

Last Answer : Answer: D

Which of the following statements concerning copper wire sized by AWG numbers is correct? A. Number 12 AWG wire has a higher current rating than 10 AWG wire. B. Number 12 AWG wire at 25°C has more resistance per 1000 ft than 10 AWG wire at 25°C. C. Number 10 AWG wire has a higher dielectric strength than 12 AWG wire. D. Number 12 AWG wire is larger than number 10 AWG wire.

Description : Which of the following statements concerning copper wire sized by AWG numbers is correct? A. Number 12 AWG wire has a higher current rating than 10 AWG wire. B. Number 12 AWG wire at 25°C has more ... dielectric strength than 12 AWG wire. D. Number 12 AWG wire is larger than number 10 AWG wire.

Last Answer : Answer: B

A saturable-core reactor operates on the principle of controlling a load winding's inductance by varying the core's _____________. A. dielectric B. permeability C. reactance D. inductance

Description : A saturable-core reactor operates on the principle of controlling a load winding's inductance by varying the core's _____________. A. dielectric B. permeability C. reactance D. inductance

Last Answer : Answer: B

ECE Board Exam March 1996 That dielectric material of an optical fiber surrounding the core A. Cladding B. Armor C. Shield D. Cover in

Description : ECE Board Exam March 1996 That dielectric material of an optical fiber surrounding the core A. Cladding B. Armor C. Shield D. Cover

Last Answer : A. Cladding

What is meant by Dielectric strength?

Description : What is meant by Dielectric strength? 

Last Answer : The maximum electrical potential gradient that a material can withstand without rupture usually specified in volts/millimeter of thickness. This also has known as electric strength. 

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.

In dielectric measurement, the dielectric loss is proportional to a) F b) V c) I d) Vsqr

Description : In dielectric measurement, the dielectric loss is proportional to a) F b) V c) I d) Vsqr

Last Answer : Ans: Vsqr

The efficiency of a transformer is mainly dependent on (A) core losses. (B) copper losses. (C) stray losses. (D) dielectric losses.

Description : The efficiency of a transformer is mainly dependent on (A) core losses. (B) copper losses. (C) stray losses. (D) dielectric losses.

Last Answer : Ans: A Core loss has prominent value over other losses

Out of the following methods of heating the one which is independent of supply frequency is (A) electric arc heating (B) induction heating (C) electric resistance heating (D) dielectric heating

Description : Out of the following methods of heating the one which is independent of supply frequency is (A) electric arc heating (B) induction heating (C) electric resistance heating (D) dielectric heating

Last Answer : (C) electric resistance heating

Which of the following tests is not done for transformer oil? (A) Flash point and acid value (B) Aniline point (C) Dielectric strength (D) Copper strip corrosion test

Description : Which of the following tests is not done for transformer oil? (A) Flash point and acid value (B) Aniline point (C) Dielectric strength (D) Copper strip corrosion test

Last Answer : (B) Aniline poin

Sparking at the brushes of a running motor could be an indication of _____________. A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption

Description : Sparking at the brushes of a running motor could be an indication of _____________. A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption

Last Answer : Answer: B

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Description : Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Last Answer : Answer: D

The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Description : The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Last Answer : Answer: B

What is the minimum recommended absorption coefficient value for AC and DC rotating machines?

Description : What is the minimum recommended absorption coefficient value for AC and DC rotating machines? 

Last Answer : Tips:  a. IR value decreases some what with an increase I applied voltage. However for machines in good condition substantially the same IR is obtained for any test voltage ... a value which after correction for temperature, may be compared with the recommended minimum value of IR. 

Log Angles machine is used to test the aggregate for (A) Crushing strength (B) Impact value (C) Abrasion resistance (D) Water absorption

Description : Log Angles machine is used to test the aggregate for (A) Crushing strength (B) Impact value (C) Abrasion resistance (D) Water absorption

Last Answer : Answer: Option C

Dorry's testing machine is used for (A) Crushing test of stone (B) Hardness test of stone (C) Impact test of stone (D) Water absorption test

Description : Dorry's testing machine is used for (A) Crushing test of stone (B) Hardness test of stone (C) Impact test of stone (D) Water absorption test

Last Answer : Answer: Option B

On nephelometry turbidity unit (NTU) is equal to the turbidity produced by (a) 1 mg SiO2 dissolved in 1 l of distilled water with the test being run according to absorption principle (b) 1 mg SiO2 dissolved in 1 l of distilled water with the test being run according t scattering principle (c) 1 mg Formazin dissolved in 1 l of distilled water with the test being run according to absorption principle (d) 1 mg Formazin dissolved in 1 l o f distilled water with the test being run according to scattering principle.

Description : On nephelometry turbidity unit (NTU) is equal to the turbidity produced by (a) 1 mg SiO2 dissolved in 1 l of distilled water with the test being run according to absorption principle (b) 1 ... Formazin dissolved in 1 l o f distilled water with the test being run according to scattering principle.

Last Answer : (d) 1 mg Formazin dissolved in 1 l o f distilled water with the test being run according to scattering principle.

Los Angles machine is used to perform (a) Crushing strength (b) Impact test (c) Water absorption (d) Abrasion resistance test

Description : Los Angles machine is used to perform (a) Crushing strength (b) Impact test (c) Water absorption (d) Abrasion resistance test

Last Answer : (d) Abrasion resistance test

Not all dielectric dielectric , but why not all dielectric dielectric ?

Description : Not all dielectric dielectric , but why not all dielectric dielectric ?

Last Answer : The substances in which electrons can move freely are called conductive. Again, substances through which electrons cannot move freely are called non-conductive. Non-conductive substances that are polarized ... . So not all die-electric non-conductive but not all non-conductive die-electric.

A dielectric slab of thickness `d` is inserted in a parallel plate capacitor whose negative plate is at `x = 0` and positive plate is at `x = 3d`. The

Description : A dielectric slab of thickness `d` is inserted in a parallel plate capacitor whose negative plate is at `x = 0` and positive plate is at `x = 3d`. The

Last Answer : A dielectric slab of thickness `d` is inserted in a parallel plate capacitor whose negative plate ... at fist, then decreases and again increase.

Identical dielectric slabs are inserted into two identical capacitors `A` and `B`. These capacitors and a battery are connected as shown in figure. No

Description : Identical dielectric slabs are inserted into two identical capacitors `A` and `B`. These capacitors and a battery are connected as shown in figure. No

Last Answer : Identical dielectric slabs are inserted into two identical capacitors `A` and `B`. These capacitors ... , which fully appears as heat in the circuit

What is the dependence of mechanical force per unit area of charged conductor on the surface charge density and the dielectric constant of the medium

Description : What is the dependence of mechanical force per unit area of charged conductor on the surface charge density and the dielectric constant of the medium

Last Answer : What is the dependence of mechanical force per unit area of charged conductor on the surface charge density and the dielectric constant of the medium

Why is the dielectric strength of vacuum infinite?

Description : Why is the dielectric strength of vacuum infinite?

Last Answer : The dielectric strength of vacuum is infinite because there isno molecule in the vacuum.

_________is a form of non-volatile storage that operates by changing the resistance of a specially formulated solid dielectric material. A. VRAM B. WRAM C. MRAM D. RRAM

Description : _________is a form of non-volatile storage that operates by changing the resistance of a specially formulated solid dielectric material. A. VRAM B. WRAM C. MRAM D. RRAM

Last Answer : D. RRAM Resistive RAM

The ratio of speed of light in air to the speed of light in another substance is called the a. Speed factor b. Index of reflection c. Index of refraction d. Dielectric constant

Description : The ratio of speed of light in air to the speed of light in another substance is called the a. Speed factor b. Index of reflection c. Index of refraction d. Dielectric constant

Last Answer : c. Index of refraction

A dielectric waveguide for the propagation of electromagnetic energy at light frequencies a. Stripline b. Microstrip c. Laser beam d. Fiber optics

Description : A dielectric waveguide for the propagation of electromagnetic energy at light frequencies a. Stripline b. Microstrip c. Laser beam d. Fiber optics

Last Answer : d. Fiber optics

Proposed the use of clad glass fiber as a dielectric waveguide a. Karpon and Keck b. Karpon and Bockham c. Bockham and Kao d. Kao and Keck

Description : Proposed the use of clad glass fiber as a dielectric waveguide a. Karpon and Keck b. Karpon and Bockham c. Bockham and Kao d. Kao and Keck

Last Answer : c. Bockham and Kao

What is the velocity factor for non-foam dielectric 50 or 75 ohm flexible coaxial cable such as RG 8, 11, 58 and 59? A. 2.70 B. 0.66 C. 0.30 D. 0.10

Description : What is the velocity factor for non-foam dielectric 50 or 75 ohm flexible coaxial cable such as RG 8, 11, 58 and 59? A. 2.70 B. 0.66 C. 0.30 D. 0.10

Last Answer : B. 0.66

What is the time delay introduced by a 75-ft coaxial cable with a dielectric constant of 2.3? A. 1.54 ns B. 11.5 ns C. 115.6 ns D. 1156 ns

Description : What is the time delay introduced by a 75-ft coaxial cable with a dielectric constant of 2.3? A. 1.54 ns B. 11.5 ns C. 115.6 ns D. 1156 ns

Last Answer : C. 115.6 ns

What is the dielectric constant of polyethylene (PE) insulator? A. 2.5 B. 3.3 C. 2.27 D. 2.1

Description : What is the dielectric constant of polyethylene (PE) insulator? A. 2.5 B. 3.3 C. 2.27 D. 2.1

Last Answer : C. 2.27

Referred to the dielectric constant of a transmission line material. A. Inductance and capacitance B. Velocity factor C. Characteristic impedance D. Propagation velocity

Description : Referred to the dielectric constant of a transmission line material. A. Inductance and capacitance B. Velocity factor C. Characteristic impedance D. Propagation velocity

Last Answer : B. Velocity factor

What is the impedance of a balance 4-wire with a diameter of 0.25 cm and spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56? A. 100Ω B. 65Ω C. 75 Ω D. 50 Ω

Description : What is the impedance of a balance 4-wire with a diameter of 0.25 cm and spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56? A. 100Ω B. 65Ω C. 75 Ω D. 50 Ω

Last Answer : A. 100Ω

When electromagnetic wave are propagated through a waveguide, they A. are reflected from the walls but do not travel along them B. travel along all four walls of the waveguide C. travel along the broader walls of the guide D. travel through the dielectric without touching the walls

Description : When electromagnetic wave are propagated through a waveguide, they A. are reflected from the walls but do not travel along them B. travel along all four walls of the waveguide C. travel along the broader walls of the guide D. travel through the dielectric without touching the walls

Last Answer : A. are reflected from the walls but do not travel along them