Description : The point of operation for a saturable reactor in a power circuit is that at which _______________. A. a large change in control current results in small change in load current B. a small change in ... change in load current D. a large change in load current causes a small change in control current
Last Answer : Answer: C
Description : Figure 'A' shown in the illustration represents a/an _______________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid
Description : An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a ____________. A. magnetic amplifier B. ship's service alternator C. three-wire DC generator D. saturable core reactor
Last Answer : Answer: B
Description : The purpose of 'R6' in the winch circuit shown in the illustration is to _______________. EL-0102 A. maintain dry conditions within the winch brake box B. keep the series field current at ... to assist the winch in stopping D. limit the armature current during lowering operation with heavy loads
Description : The voltage at the reference electrode of the circuit shown in the illustration is applied to the input of a/an ______________. EL-0090 A. class A detector whose output drives an ... drives an 2-stage isolation transformer D. magnetic amplifier whose output controls a saturable reactor
Last Answer : Answer: D
Description : Figure 'A' of the diagram shown in the illustration represents a ______________. EL-0092 A. differential transformer B. saturable reactor C. synchro system D. magnetic amplifier
Description : Basically, a magnetic amplifier is a saturable reactor with the addition of _____________. A. AC to the bias winding B. variable capacitance to all windings C. eddy current protectors D. a rectifier in the load circuit
Description : Figure 'B' shown in the illustration represents a/an ____________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid
Last Answer : Answer: A
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
Description : A silicon controlled rectifier (SCR) is a solid state device used to change ________________. A. DC to AC and control relatively low load current B. AC to DC and control relatively high load ... to AC and control relatively high load current D. AC to DC and control relatively low load current
Description : Reactors in commercial nuclear power plants in the U.S. are often referred to as thermal reactors. A thermal reactor uses: w) fissionable plutonium-239 as fuel. x) a relatively low heat output. y) neutrons moderated to relatively low energies. z) liquid sodium as a coolant.
Last Answer : ANSWER: Y -- NEUTRONS MODERATED TO RELATIVELY LOW ENERGIES.
Description : How is the effect of load flux on control flux eliminated in a saturable-core reactor?
Last Answer : use two load windings whose flux effects cancel in the core of the reactor or use two load windings on two toroidal cores so that load flux always aids control flux in one core and opposes control flux in the other core.
Description : Justify the use of saturable reactor to control the magnitude of welding current.
Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
Description : Although saturable reactors are extremely useful in some applications, their gain is low because of ____________. A. core hysteresis losses B. inductive reactance in the control winding C. IR drop throughout the load winding D. all of the above
Description : In the illustrated motor, roller bearings are used because __________. EL-0001 A. of their ability to absorb moderate thrust loads B. they electrically insulate the rotor from the frame reducing ... clearance between the rotor and stator is generally as close as mechanical tolerance will permit
Description : If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of ... the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents
Description : Due to its construction, the component in figure 'A' shown in the illustration has which of the listed advantages compared to bipolar devices? EL-0078 A. Operates with higher voltages and ... as a controllable rectifier. D. Has very high input resistance and uses practically no gate current.
Description : In the illustration, the component labeled 'EXC' is _______. EL-0003 A. a separate class II regulated DC generator for critical direct current loads B. a generator feeding the FLD ... to drive the governor for turbogenerator speed. D. the electronic driver for the switchboard metering circuits
Description : The secondary output voltage of a saturable core frequency meter is the function of (a) only frequency (b) only primary voltage (c) both (a) and (b) (d) None of above
Last Answer : C) Both a and b
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 : The horizontal line which cuts across 'L1' shown in figure 'A' of the illustration indicates a/an ______________. EL-0091 A. iron core B. saturable core C. air gap D. capacitive coupling
Description : In an AC circuit, the inductive reactance of a coil varies with the _______________. A. resistance of the circuit B. frequency of the circuit C. voltage of the circuit D. current of the circuit
Description : The frequency of an AC generator is adjusted by means of the ____________. A. main alternator field rheostat B. exciter field rheostat C. prime mover governor control D. equalizing reactor
Description : The operator of electrical motors should keep a constant check on the loads they carry because _____________. A. low loads necessitate frequent insulation cleaning B. exceeding nameplate values shortens ... wasted if full loading is not utilized D. power factor correction methods are load dependent
Description : Nickel-cadmium batteries are superior to lead-acid batteries at high discharge rates because they _______________. A. deliver a large amount of power and can be recharged in a shorter time B. need ... less mounting space C. have higher output voltages and require no maintenance D. all of the above
Description : Electrostatic type instruments are mainly used for measurement of: a) Heavy currents b) Low currents c) Low voltages d) High voltages
Last Answer : Ans: D
Description : An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. ... between the armature and the bus D. cause high currents to be induced in the field windings
Description : The vertical dotted line connecting the small circular symbols at coordinates '05L', '09L', '13L', '21L', '25L', etc., shown in the illustration, indicate that all _______________. EL-0100 A. contacts are ... board 'TB2' C. wires are grounded at both ends of the line D. wires have a common shield
Description : Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an _______________. A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water
Description : An electric tachometer receives the engine speed signal from a _______________. A. small generator mounted on the engine B. bimetallic sensing device C. stroboscopic sensing device D. vibrating reed meter generating a voltage proportionate to engine speed
Description : What FCN was implemented to avoid reactor trip on 220V-DC failure of PHT and PPP breakers?
Last Answer : The breaker close position supervision relay VAA 21 is changed by VAJC type, contacts position do not change if 220V-DC is lost now.
Description : A useful instrument for checking A.C. motor performance by measuring possible unbalanced currents is the _____________. A. hand or battery-operated megger B. vibrating-reed frequency meter C. hook-on voltmeter-ammeter D. D'Arsonval iron-vane probe
Description : An important factor in reducing D.C. motor commutator wear is _______________. A. keeping the ambient humidity as low as possible B. ensuring a very low brush current density C. establishing the copper oxide surface film D. all of the above
Description : A slow continual loss of electrolyte level from one cell of a storage battery could be due to _______________. A. a cracked casing B. too low a charging rate C. the specific gravity being higher than normal D. one filler cap installed too tightly
Description : If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces
Description : Coast Guard Regulations (46 CFR), require that an indicating light at the propulsion control station will operate if overloading or overheating occurs in a _______________. A. forced draft blower motor B. steering gear motor C. fuel pump motor D. condensate pump motor
Description : The purpose of the 'heater resistors' for the winch circuit shown in the illustration is to _______________. EL-0102 A. limit the current in the heater circuit B. dispel moisture in the ' ... panel C. keep the winch brake housing below the dew point D. maintain winch motor operating temperature
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 : As shown in the illustration, when the 'speed control' system is in 'SPLIT' _______________. EL-0096 A. Relays #1, #5 and #8 are not used B. the 'slew rated controller' is grounded through Relay ... E/P converters' are bypassed and air is fed directly to the governors via the 'load sharing valve'
Description : The 'function generator' of the control circuit illustrated _______________. EL-0095 A. can be programmed to produce a non-linear output for a linear input depending on operating conditions B. is used for ... which or how many engines are needed for a required vessel speed D. all of the above
Description : 48.During light loads, the transformer efficiency is low because A. Secondary output is low B. Transformer losses are high C. Fixed loss is high in proportion to the output D. Cu loss is small
Last Answer : C. Fixed loss is high in proportion to the output
Description : Pressure in a Pressurised Water Reactor (PWR) is used for (A) Maintaining constant pressure in the primary cooling circuit under varying loads (B) Superheating the steam (C) Pressurising the water in the primary coolant circuit (D) None of these
Last Answer : (A) Maintaining constant pressure in the primary cooling circuit under varying loads
Description : The dc motor used for intermittent high torque loads is (1) dc series motor (2) dc shunt motor (3) differential compound motor (4) cumulative compound motor
Last Answer : 4 cumulative compound motor
Description : Copper brushes in D.C. machine are used (a) where low voltage and high currents are involved (b) where high voltage and small cur-rents are involved (c) in both of the above cases (d) in none of the above cases
Last Answer : Ans: a
Description : During a merger and acquisition transaction, the ability to find and use good comparable data for a valuation is relatively ____________. a) easy because each successful company within an industry ... depth, product diversity and access to lines of credit seldom match the company being valued
Last Answer : d) difficult because size differential, management depth, product diversity and access to lines of credit seldom match the company being valued
Description : Two 100 watt light bulbs are connected in parallel across a 100 volt power supply. The total power developed in the circuit is _______________. A. 200 watts B. 100 watts C. 50 watts D. equal to the product of the amperes times the voltage in each branch
Description : The winch shown in the illustration will not operate in any speed in the lowering direction and at an abnormal speed in 'first point hoist'. The possible cause is that _______________. EL-0102 A. ... '1M' in the power circuit are badly corroded D. master switch contacts 'MS6' have weak springs
Description : When troubleshooting a console circuit card suspected of being faulty, the last step would be to _______________. A. check the fuses and voltage levels of all power supplies in the console B. clean dust ... -on types D. substitute a new or repaired spare card and check the operation of the circuit
Description : The +5 volt regulated power supply shown in the illustration is fed directly from the _______________. EL-0094 A. 115 volt AC bus B. Annunciator Module C. +24 volt supply D. Annunciator Controller
Description : The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above