Description : What type of meter is shown and what is the value of the quantity being measured for each meter in figure1-49?
Last Answer : a. A dc ammeter, 90 mA dc b. A dc voltmeter, 200 V dc c. An ac voltmeter, 4.6 V ac d. An ohmmeter, 400 ohms
Description : What type of meter is shown and what is the value of the quantity being measured for each meter in figure 1-51?
Last Answer : (A) Megger (megohmmeter), infinity; (B) Wattmeter, 9.5 kilowatts (9,500 watts). (C) Watt-hour meter, 2.693 megawatt-hours 2,693 kilowatt-hours) (2,693,000 watt-hours).
Description : Indicate the three types oftransmissionline energylosses. a. I2R, R , and temperature b. Radiation, I2R, and dielectric heating c. Dielectric separation, insulation breakdown, and radiation d. Conductor heating, dielectric heating, and radiation resistance.
Last Answer : b. Radiation, I2R, and dielectric heating
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 : 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
Description : With both ends of a three conductor cable disconnected and arranged without the conductors touching each other, an ohmmeter reading of 'zero' ohms between the ends of one conductor would indicate _____________. A. continuity B. a partial ground C. the resistance is infinite D. a short circuit
Last Answer : Answer: A
Description : You are performing an out-of-circuit test of the semi-conductor shown in the illustration. Using an ohmmeter on 'low power' position and with leads properly installed, which of the listed results would indicate a good ... lead on 'A' and red lead on 'C'; and a high reading with the leads reversed.
Last Answer : Answer: C
Description : You are performing an out-of-circuit test on the semi-conductor shown in the illustration. Using an ohmmeter on 'low power' setting and with leads properly inserted, which of the listed results would indicate a good ... lead on 'A' and red lead on 'C'; and a high reading with the leads reversed.
Description : While measuring frequency response, as the signal generator approaches the lowest and highest frequency the recorder can effectively record, the VTVM reading drops to less than - 3 dB. What does this indicate?
Last Answer : The upper and lower limits of the frequency response specification for that tape recorder.
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 : 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 : 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 : Reading a 58 dBrn, at a +7 test point is equal to ________ dBa0. A. 26 B. 65 C. 51 D. 46
Last Answer : D. 46
Description : Reading a 58 dBrnC on your Western Electric 3A test set at a +7 test point is equal to ______ dBrnc0. A. 58 B. 51 C. 65 D. 27
Last Answer : B. 51
Description : What happens when a frequency meter is adjusted to the frequency of the signal being measured?
Last Answer : Power is absorbed by the frequency meter cavity; and a pronounced dip in power, at the output, will be observed.
Description : In swept-frequency testing the impedance of a transmission line, what electrical characteristic is actually being measured?
Last Answer : Swr on the transmission line.
Description : How is a series-type ohmmeter connected to the circuit being measured?
Last Answer : The ohmmeter is connected in series with the resistance to be measured.
Description : How the ammeter’s effect on the circuit being measured is kept to a minimum?
Last Answer : The resistance of the ammeter must be much smaller than the circuit load.
Description : How does an ammeter affect the circuit being measured?
Last Answer : Since the ammeter is a resistor in series with the load, it increases the resistance of the circuit and lowers circuit current.
Description : Which of the following types of insulation will begin to deteriorate FIRST as a result of the heat generated in the conductor it surrounds? A. Varnished cloth B. Rubber C. Silicon D. Asbestos
Last Answer : Answer: B
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
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 : Copper is often used as an electrical conductor because it _______________. A. has high resistance at low temperatures B. has a highly polished surface C. is able to pass current with little opposition D. holds insulation together well
Description : What is the characteristic impedance of a coaxial line with the following data: inner diameter = 0.2 in., center conductor diameter = 0.06 in., insulation = Teflon. A. 200Ω B. 75Ω C. 50Ω D. 150Ω
Last Answer : C. 50Ω
Description : Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conductor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids
Last Answer : (d) there is a danger of breakdown of insulation due to the presence of voids
Description : In a cable, the maximum stress under operating conditions is at (a) insulation layer (b) sheath (c) armour (d) conductor surface
Last Answer : (d) conductor surface
Description : The thickness of the layer of insulation on the conductor, in cables, depends upon (a) Reactive power (b) Power factor (c) Voltage (d) Current carrying capacity
Last Answer : (c) Voltage
Description : The size of a conductor used in power cables depends on the (A) operating voltage. (B) power factor. (C) current to be carried. (D) type of insulation used.
Last Answer : (C) current to be carried.
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
Description : The thickness of insulation provided on the conductor depends on?
Last Answer : The thickness of insulation provided on the conductor depends on the magnitude of voltage on the conductor.
Description : The insulation on a current carrying conductor is provided?
Last Answer : The insulation on a current carrying conductor is provided to prevent leakage of current, to prevent shock.
Description : Pointer of an analog ohmmeter reading close to zero, indicates the resistor being measured is: A. overheated B. shorted C. open D. reversed
Last Answer : Pointer of an analog ohmmeter reading close to zero, indicates the resistor being measured is: shorted
Description : Insulation resistance is measured by which meter?
Last Answer : megger
Description : What stripping tool would NOT be used to strip glass braid insulation?
Last Answer : Hot-blade stripper.
Description : What materials are commonly used as cushions between cable insulation and metallic armor?
Last Answer : Jute and Asphalt coverings.
Description : State the reasons that the Navy is getting away from the use of asbestos insulation.
Last Answer : Breathing asbestos fibers can cause lung disease and/or cancer
Description : Define insulation resistance.
Last Answer : The resistance to current leakage through the insulation.
Description : What is a normal indication on a megger when checking insulation?
Last Answer : Infinity.
Description : What instrument is used for measuring the insulation resistance of cables?
Last Answer : Megohmmeter (megger).
Description : While testing a semi-conductor diode with an ohmmeter, both the forward and reverse readings are almost in the infinity range. This would indicate that the unit is _____________. A. good B. open C. grounded D. shorted
Description : If you disconnect and arrange both ends of a three conductor cable, without any contact between the individual conductors, an indicated ohmic value between the ends of a single conductor would indicate ... resistance C. the presence of a partial ground D. that the conductor is not short circuited
Description : If air gap readings for an electical generating machine have changed significantly from the last reading, you should check _________. A. the bearings B. insulation readings and machine cleanliness C. the prime mover thrust bearing D. the field coil bolts for the proper torque values
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
Description : An insulation resistance reading is taken at 20°C and found to be 10 megohms. What would you expect the resistance reading to be at 40°C? A. 2.5 megohms B. 10 megohms C. 15 megohms D. 20 megohms
Description : When using a megohmmeter to test insulation, good insulation will be indicated by _____________. A. slight kicks of the needle down scale B. a downward dip followed by a gradual climb to the true resistance ... C. a gradual rise in the pointer reading at the outset D. the initial dip of the pointer
Description : Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test, because the ___________. A. static charge of the machine ... number of leakage paths C. insulation may be damaged D. insulation may be covered with moisture
Description : An insulation resistance test is performed on a particular piece of electric equipment. In addition to the resistance reading, what information listed below should be entered in the electrical log? A. ... D. The complete nameplate data from the resistance test instrument used to obtain the reading.
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
Description : If 450 volts AC were measured across the load as shown in the illustration it would indicate a/an _______________. EL-0083 A. open winding between 'H1' and 'X1' B. properly operating circuit C. open winding between 'X1' and 'X4' D. ground on one side of 'Ep'