FUNCTION -5 (ELECTRICAL)

121. A silicon controlled rectifier (SCR) is a solid state device used to change  ____________.
     1. DC to AC and control relatively low load current
     2. AC to DC and control relatively high load current
     3. DC to AC and control relatively high load current
     4. AC to DC and control relatively low load current

ANS.: B

122. Which of the following conditions will occur if the solenoid coil burns out on a cargo winch with an electrical brake?
     1. The brake will be set by spring force.
     2. The motor will over speed and burn up.
     3. The load suspended from the cargo boom will fall.
     4. Nothing will happen; the winch will continue to operate as usual.

ANS.: A

123. Which of the listed battery charging circuits is used to maintain a wet cell, lead-acid, storage battery in a fully charged state during long periods of disuse?
     1. Normal charging circuit
     2. Quick charging circuit
     3. Trickle charging circuit
     4. High ampere charging circuit

ANS.: C

124. The full torque electric brake on an electric cargo winch functions to
     1. act as backup brake in the event the mechanical brake should fail
     2. automatically hold the load as soon as current to the machine is shut off
     3. automatically govern the lowering speed of the load
     4. automatically govern the hoisting speed of the load

ANS.: B

125. For full wave rectifier ripple factor is?
     1. 482
     2. 21
     3. 582
     4. 51

ANS.: A

129. In the event of a power failure during cargo loading operations, the movement of an electric powered cargo winch will be stopped by
     1. a manual override switch
     2. the weight of the load on the boom
     3. a spring set brake
     4. a hand operated band brake

ANS.: C

130. A ground can be defined as an electrical connection between the wiring of a motor and its
     1. shunt field
     2. circuit breaker
     3. metal framework
     4. Interpol

ANS.: C

131. The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the
     1. prime mover speed
     2. exciter output voltage
     3. load on the alternator
     4. number of poles

ANS.: B

132. Which of the following statements represents the main difference between a relay and a contactor?
     1. Contactors control current, relays control voltage.
     2. A relay is series connected and contactor is parallel connected.
     3. Contactors can handle heavier loads than relays.
     4. Contactors are made from silver and relays are made from copper.

ANS.: C

133. The electrolyte used in a nickel-cadmium battery is distilled water and
     1. diluted sulfuric acid
     2. potassium hydroxide
     3. lead sulfate
     4. zinc oxide

ANS.: B

134. Which of the damages listed can occur to the components of a winch master control switch, if the cover gasket becomes deteriorated?
     1. Overheating of the winch motor.
     2. Contamination of lube oil.
     3. Sparking at the winch motor brushes.
     4. Rapid corrosion of switch components.

ANS.: D

135. An accidental path of low resistance, allowing passage of abnormal amount of current is known as a/an
     1. open circuit
     2. short circuit
     3. polarized ground
     4. ground reference point

ANS.: B

136. A resistance in a circuit of unknown value is to be tested using the voltmeter/ammeter method. Therefore, the meters should be connected with
     1. both meters in series with the resistance
     2. both meters in parallel with the resistance
     3. the ammeter in series and the voltmeter in parallel with the resistance
     4. the ammeter in parallel and the voltmeter in series with the resistance

ANS.: C

137. A direct current passing through a wire coiled around a soft iron core is the description of a simple
     1. magnetic shield
     2. electromagnet
     3. piezoelectric device
     4. electromagnetic domain

ANS.: B

138. The use of four diodes, in a full-wave bridge rectifier circuit, will
     1. provide unidirectional current to the load
     2. allow a very high leakage current from the load
     3. convert direct current to alternating current
     4. offer high opposition to current in two directions

ANS.: A

139. A magnetic blowout coil in a DC motor controller contractor functions to
     1. open contact rapidly
     2. reduce contact wear
     3. adjust opening spring tension
     4. provide “snap-action” in the contractor

ANS.: B

140. The method used to produce electron emission in most vacuum tubes is known as
     1. photoelectric emission
     2. secondary electric emission
     3. cold cathodic electric emission
     4. thermionic emission

ANS.: D

141. Which of the listed devices is used to measure pressure and convert it to an electrical signal?
     1. Transducer
     2. Reducer
     3. Transformer
     4. Rectifier

ANS.: A

142. Grounds occurring in electrical machinery as a result of insulation failure are usually caused by
     1. deterioration due to age
     2. excessive heat
     3. vibration
     4. all of the above

ANS.: D

143. The amount of voltage induced in the windings of an AC generator depends on
     1. the number of conductors in series per winding
     2. the speed at which the magnetic field passes across the winding
     3. the strength of the magnetic field
     4. all of the above

ANS.: D

144. The device that most commonly utilizes the principle of electromagnetic induction is the
     1. diode
     2. transformer
     3. transistor
     4. rheostat

ANS.: B

145. A tubular fuse should always be removed from a fuse panel with
     1. a screwdriver
     2. a pair of insulated metal pliers
     3. any insulated object
     4. fuse pullers

ANS.: D

146. One factor that determines the frequency of an alternator is the
     1. number of turns of wire in the armature coil
     2. number of magnetic poles
     3. strength of the magnets used
     4. output voltage

ANS.: B

147. Which of the motors for the devices listed below is fitted with an instantaneous overload relay?
     1. Fan
     2. Pump
     3. Winch
     4. Machine tool

ANS.: C

148. Which of the following statements concerning an analog device and a digital device is correct?
     1. The variables in digital systems are fixed quantities, and the variables in analog systems are continuous quantities.
     2. There are no basic differences between the two systems.
     3. Analog devices are superior in accuracy compared to digital devices.
     4. Operations in a digital device are performed simultaneously.

ANS.: A

149. The number of cells in a 12-volt lead-acid battery is
     1. three cells
     2. four cells
     3. six cells
     4. twelve cells

ANS.: C

150. When choosing a battery for a particular application, major consideration should be given to the battery’s
     1. amp-hour capacity
     2. terminal polarity
     3. stability under charge
     4. ambient temperature rise

ANS.: A