Stationary Engineer Electric Exam Questions With 100% Correct Answers

Stationary Engineer Electric Exam Questions With 100% Correct Answers An AC circuit consists only of a pure inductance and a power source. The relationship between the voltage and the current in this circuit is that the - answercurrent lags the voltage The power factor of a load is equal to the ____________ power divided by the ____________ power. - answerTrue ; apparent A 10-ohms and 20-ohms resistor are connected in parallel. The total line current drawn by this parallel combination is 30 amps. Under these conditions, the line voltage will be ____________ volts. - answer200 A 20-ohm resistor is connected in series with a parallel combination of two resistors, one of which is 10-ohms, the other 40-ohms. If the voltage across the parallel combination is 40 volts, the voltage across the 20-ohm series resistor is ________ volts. - answer100 A certain 120-volts single-phase AC circuit has a power factor of 80 percent and a watt-meter reading of 1150 watts. The current drawn by the circuit is _________ amperes. - answer12 If the voltage between lines of a 3-phase, 3-wire delta connected system is 2400 volts, then the phase voltage is _____________ volts - answer2400 A circuit consists of an inductive reactance of 15 ohms and a resistor of 20 ohms in series across a 100-volts, 60 cycles AC supply. The current in this circuit is ____________ amperes. - answer4 A 3 phase, 3 wire, 208 volt, 60 cycles AC service supplies a balanced load consisting of three 30 ohms resistors connected wye. The line current under these conditions os MOST NEARLY ___________ amperes. - answer6.9 If the level of the electrolyte in a lead acid storage battery falls below the top of the plates because of evaporations under normal operating conditions, it is BEST to add - answerWater A 600 volt cartridge fuse must have knife blade contacts if its current rating exceeds _____________ amperes. - answer60 When the magnitude of the short circuit currents in a feeder circuit must be limited, this is USUALLY accomplished by means of - answerreactors The cross sectional area in circular mils of a standard cable having 37 strands, each of which ha a diameter of 90 nils, is MOST NEARLY - answer300,000 A coil having an average diameter of 4 inches is to be made up from a 1,260 ft long length of wire. The numbers of turns in this coil will be MOST NEARLY - answer1,200 The device commonly known as a growler is FREQUENTLY used to - answertest DC armature windings for shorts When a megger is applied alternately to the two leads of a direct current electrolytic capacitor, the reading will - answerstart at zero but increase gradually for one of the connections The device used to convert direct current to alternating current is called - answerinverters Of the following conditions, the one which is MOST likely to cause flashing or excessive arcing from brush to brush in a motor is - answerExcessively high voltage on the line The currents in the armature equalizer connections in a DC generator are - answeralternating currents A generating station has one 1000 Kw and two 2000 Kw generators. To supply 2000 Kw MOST economically, the operating conditions should be - answerone 2000 Kw generator at full load The terminal voltage of a DC shunt generator having an armature current of 100 amperes, an armature resistance of 0.02 ohms, and a generated E.M.F of 222 volts is MOST NEARLY ______________ volts. - answer220 The number of poles in the field of an alternator generating voltage at a frequency of 60 cycles per second while rotating at 1200 rpm is - answer6 If the field of a shunt motor opens while running, the motor will - answerrun away To reverse the direction of rotation of a cumulative compound motor, and not have it run as a differential compound motor, reverse the connections to the ____________ field. - answershunt field and to the series A main contributing factor to motor stator failure usually is - answerdirt The input of a motor is 40,000 watts and efficiency is 80 percent. The TOTAL energy loss is __________ watts. - answer8,000 The full load current of a three-phase 5 hp motor operating at 200 volts, 60 cycles, and having an efficiency of 80 percent and a power factor of 85 percent is MOST NEARLY ____________ amperes. - answer14.4 Of the following motors, the one that has the best speed regulation is the motor. - answershunt The full load speed of a 60-cycle 208 volt, 3 phase induction motor having 6 poles and operating with a slip of 10% is MOST NEARLY___________ r.p.m - answer1080 Of the following, a MAJOR advantage of an AC synchronous motor is that it(s) - answercan be used for power factor correction If the field current of a synchronous motor is increased to a point which makes the synchronous motor overexcited, the - answermotor will take a leading current When transformers are to be operated in parallel, it is NOT necessary that the transformer have the same - answerKVA rating A transformer rates at 200 KVA is FULLY loaded with a lagging power factor of 80% when it is supplying - answer160 KW If the current in the primary of a current transformer is 500 amperes and the transformer has a ratio of 100 to 5, an ammeter connected to the secondary will read MOST NEARLY___________ amperes. - answer25 Assume that a switchboard ammeter which is connected to a current transformer is damaged and must be removed without interrupting the service. Of the following, an ESSENTIAL precaution to be taken before disconnecting the ammeter is to - answershort the secondary of the transformer A DC relay is rated at 6 volts and 120 ohms. This relay can be operated from a 120 volt line by connecting a ___________ ohm resistance in __________ with relay - answer2280: series Some relays are provided with dash-pots. The FUNCTION of these dash-pots is to provide - answerdelayed time action An ammeter has a full scale deflection for a current of 0.01 amperes and an internal resistance of 20 ohms. In order to have the ammeter read full-scale for a current of 10 amperes and not damage its movement, a shunt should be used having a value of__________ ohms. - answer0.02 An air circuit breaker has contacts that flash. The MOST probable cause of this trouble is that the - answerbarriers are broken The MAIN purpose of a shunt trip on a circuit breaker is to - answerpermit the breaker to be opened electrically from a remote location, regardless of load conditions at the breaker The grid-controlled gas-type electronic tube MOST often used in motor control circuits is the - answerthyratron Under normal atmospheric conditions, a pressure gauge that reads 24 inches of mercury is indicating an absolute pressure of MOST NEARLY_____________ P.S.I. - answer26.5 The PRIMARY function of a hydrometer is to measure the rate of - answerrelative humidity A venturi meter is used to measure the rate of - answerfluid flow The PRINCIPLE thickening agent used in lubricating greases is - answermetallic soap The specific gravity of liquid is USUALLY determined by means of a - answerhydrometer The pull required on the fall line (negating friction) to hoist a 120 pounds weight, using a four- part block and tackle, is ___________ lbs. - answer30 Of the following terms, the one which does NOT describe a way of finishing the ends of a rope is the - answerbight When hoisting a load by means of sling, the stress in each leg of the sling will - answerincrease as the angle between the horizontal and the sling leg decreases The MAXIMUM pressure in an upright cylinder 6 feet in diameter, 8 feet high, and open at the top, when filled tot he brim with water, is MOSTLY NEARLY ______________ lbs/. - answer500 The MAXIMUM height to which water can be lifted by means of suction alone, at sea level, is APPROXIMATELY _____________ feet. - answer34 The TOTAL number of 4 inch diameter pipe that is required to equal the water flow capacity of an 8 inch diameter pipe (negating friction) is - answer4 The number of threads, per inch, on the standard machine screw MOST suitable for general use is - answer32 The friction losses which occur when water flows through a pipe vary MOST NEARLY _____________ with the ____________. - answerdirectly; velocity squared Small by-pass lines are sometimes furnished around large gate valves MAINLY to - answerbalance the pressure on the gate when the valve is being opened The sudden surge caused by an abrupt change in the speed of the pumps in a closed liquid piping system is USUALLY called - answerwater hammer The valve that permits water to flow one direction only is the ____________ valve - answercheck Most flanged butterfly valves can be brought from a fully closed position to a fully opened position in _____________ turn(s). - answera quarter The efficiency of two centrifugal pumps operating in parallel is ___________ of one of the pumps operating alone. - answerpractically the same as that