Description : A megger is to measure insulation resistance of a cable. The cable should be connected to (a) Battery (b) DC supply (c) AC supply (d) No supply
Last Answer : majorly in DC as well as AC......but ans is Battery
Description : A megger is being used to test the insulation of an AC generator. The resistance value of a dry, clean winding will _____________. A. continue to rise as test potential is maintained, ... , becoming fairly steady after 5-7 minutes D. stabilize after approximately 2-4 minutes of fluctuation
Last Answer : Answer: A
Description : When troubleshooting motor controllers, a shorted relay or contactor coil is often indicated by _______________. A. a resistance reading of 'infinity' on an ohmmeter B. charred insulation and/or a blown ... of the coil's leads to ground D. a higher-than-normal voltage reading across the winding
Last Answer : Answer: B
Description : A generator has been exposed to water and is being checked for its safe operation. Therefore, it is necessary to _______________. A. check for shorted coils with a growler B. take moisture readings with a ... a megger D. ground the commutator, or slip rings and run it at half load for 12 hours
Last Answer : Answer: C
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
Description : Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by ____________. ... an electric welder and feeding it into the armature while running the motor at full speed
Description : The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator
Description : The output voltage of a 440 volt, 60 Hz AC generator is controlled by the ______________. A. load on the alternator B. load on the prime mover C. speed of the prime mover D. exciter output voltage
Description : The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the _____________. A. prime mover speed B. exciter output voltage C. load on the alternator D. number of poles
Description : A galvanometer is an instrument used to measure ___________. A. thickness of galvanized metal B. resistance of electrical wiring insulation C. very small amounts of current or voltage D. quantity of galvans in an electric circuit
Description : As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to _____________. A. draw a one line diagram of the circuitry B. test all fuses and measure the line voltage C. take megger readings D. insulate the apparatus from ground
Description : AC and DC generators are similar in that they _____________. A. both generate alternating voltages B. both rectify the voltage before delivery C. are constructed at the same physical size for the same kilowatt rating D. both supply three-phase power
Description : Define the followings. Insulation level, Rated short circuit breaking current, Making current, Short time rating, Impulse withstand voltage, Power frequency withstand voltage .
Last Answer : Insulation level - it is the combination of rated voltage, the corresponding impulse withstand voltage, which together characterize the insulation of the equipment as regards its ability to withstand ... wave of power frequency (50 Hz) which the insulation of equipment should withstand.
Description : The illustrated test is being conducted on the motor shown in the illustration, if the lamp lights dimly then ________. EL-0027 A. the bulb needs to be changed to one with a higher wattage rating B. ... D. a ground or partial ground is indicated, a check with a megger should confirm the lamp test
Description : Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor? A. Higher than normal operating temperature. B. Excessive vibration at normal speed. C. Sparking at the brushes. D. High 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
Description : The need for insulation cleaning may be determined by _____. A. visual inspection for dirt accumulation B. high megger readings C. low operating temperature D. the time period since the last cleaning
Description : Electrical machinery insulation will break down more rapidly due to _________________. A. low loading of motors and generators B. frequent megger testing C. high temperatures and vibration D. high operating frequencies
Description : Routine maintenance of a ship's service alternator should include ______________. A. changing the pedestal bearing insulation yearly B. megger testing of all rectifying diodes C. lubricating excitation slip rings D. periodic cleaning of the air filters or screens
Description : What is a normal indication on a megger when checking insulation?
Last Answer : Infinity.
Description : What is the procedure for using a megger to check the insulation of a conductor?
Last Answer : Connect one lead to the insulation and one lead to the conductor. Turn the handcrank until it starts to slip. Note the reading
Description : What is the normal indication on a megger when checking insulation?
Last Answer : infinity
Description : Why is a Megger used for insulation test and not a multi meter?
Last Answer : With a megger,a voltage of not less than 500 volts DC is used for testing the insulation resistance of windings. With a multi-meter, the voltage used is not more than 3-volts DC. Megger uses high impedance testing and is therefore more accurate than a multi-meter
Description : If reading the AC voltage from the line lead of a 440 VAC controller the range switch illustrated should be set to ___________. EL-0047 A. 1,000 V B. 250 V C. R X 10,000 D. Unable to safely read with this meter.
Description : A process electric heater is taking an hour to reach the desired temperature while operating at 440 V. It will take ------- hours to reach the same temperature if the supply voltage is reduced to 220 V. a) 2 b) 3 c) 4 d) 5
Last Answer : c) 4
Description : Lead lined equipments & vessels are suitable for handling (A) Hydrochloric acid (10%) (B) Nitric acid (C) Sulphuric acid upto 60°C (D) All (A), (B) and (C)
Last Answer : (C) Sulphuric acid upto 60°C
Description : Name the method used to measure following resistances:- (i) Low resistance (ii) Medium resistance (iii) Insulation resistance (iv) Earth resistance.
Last Answer : Following are the methods used to measure resistances:- (i) Low resistance: 1.Voltmeter-Ammeter Method 2. Kelvin's Double bridge Method (ii) Medium resistance: 1.Voltmeter-Ammeter Method 2. ... of Charge Method (iv) Earth resistance : 1. Fall of Potential Method 2. Earth tester
Description : Why should you never place floppy disks near telephones or other electronic equipments that generate magnetic fields?
Last Answer : Magnetic fields can destroy the data on a disk.
Description : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be
Last Answer : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be 1165 Nm
Description : In preparing to take insulation resistance readings on a main generator, the windings should be grounded for about 15 minutes prior to the test to _____________. A. allow accurate zeroing of the meter ... the windings D. help the windings to cool to the same temperature as the ground test connection
Description : You are testing the insulation in an AC generator with a megohmeter. The resistance value of a dry, clean winding will ____________. A. continue to rise as the test potential is maintained, ... fairly steady after 5 to 7 minutes D. stabilize after approximately 2 to 4 minutes of fluctuation
Description : Discharge switches are often located on hand-driven meggers. The purpose of these switches is to discharge capacitive charges stored in the _____________. A. megger hand generator B. megger movement coils C. tested equipment while conducting test D. tested equipment after testing
Last Answer : A wire of 0.14 mm diameter and specific resistance 9.6 micro-ohm-cm is 440 cm long. The resistance of the wire will be 27.4 ohm.
Description : When working on electrical circuits containing large capacitors, in addition to deenergizing the circuit, which of the listed precautions should also be taken? A. Keep all radio equipment ... capacitor insulation resistance. C. Ground the capacitor terminals. D. Check capacitor circuit polarity.
Description : Before using a volt-ohmmeter to measure resistance readings, you should _____________. A. replace all batteries B. test the insulation resistance of the leads C. make sure the test leads do not touch D. hold the leads together and 'zero' the meter
Description : Which of the listed statements is correct when using an analog multimeter as an ohmmeter? A. The pointer should be adjusted to zero each time a new resistance range is selected. B. The ... C. Ohmmeters are not sufficiently sized to measure conductor insulation resistance. D. All of the above.
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
Description : The cylindrical windings using circular conductors are used for current rating of (a) upto 20 A (b) upto 40 A (c) upto 60 A (d) upto 80 A
Last Answer : (d) upto 80 A
Description : Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto (a) 10 MW (b) 30 MW (c) 60 MW (d) 150 MW
Last Answer : (c) 60 MW
Description : Upto the critical radius of insulation, added insulation, will (A) Increase the heat loss (B) Decrease heat loss and will have no effect beyond that (C) Decrease heat flux (D) Reduce convection heat loss compared to conduction heat less
Last Answer : Option B
Description : Megger is used to measure (a) very high resistance or insulation resistance. (b) low resistance. (c) high resistance. (d) very low resistance.
Last Answer : (a)very high resistance or insulation resistance
Description : If shunt generator delivers 100 A at 200 V, and the resistance of the shunt field and armature are 100 ohm and 0.01 ohm respectively, the generated e.m.f. will be : - a) 212 V b) 205 V c) 210 V d) 201.02 V
Last Answer : If shunt generator delivers 100 A at 200 V, and the resistance of the shunt field and armature are 100 ohm and 0.01 ohm respectively, the generated e.m.f. will be : - 201.02 V
Description : The resistance of a silver wire at `0^(@)C " is " 1.25 Omega`. Upto what temperature it must be heated so that its resistance is doubled ? The tempera
Last Answer : The resistance of a silver wire at `0^(@)C " is " 1.25 Omega`. Upto what temperature ... temperature be same for all silver conductors of all shapes ?
Description : The reading at 'V' on the megger scale shown in the illustration, is __________. EL-0044 A. 40 meg ohms B. 0.40 meg ohms C. 4.0 kilo ohms D. 40,000 ohms
Description : When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by the megohmmeter pointer _____________. A. fluctuating around a ... slightly downscale as voltage is applied D. continually rising as the test voltage is applied
Description : During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points
Description : When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by the megohmmeter's pointer _____________. A. dipping toward ... kicking slightly down scale as voltage is applied D. fluctuating around a constant resistance reading
Description : Insulation resistance of high voltage circuit breakers is more than (a) 1 mega ohms (b) 10 mega ohms (c) 100 mega ohms (d) 500 mega ohms
Last Answer : (c) 100 mega ohms
Last Answer : Insulation resistance of high voltage circuit breakers is more than 100 mega ohms.
Description : When testing for blown fuses in a three-phase supply circuit to a motor, you should first ___________________. A. apply the megger across the tops of the line fuses B. apply an ammeter diagonally across ... of the line fuses D. ensure the circuit is de-energized, and then use a continuity tester