WorksheetsRamsey Test
Total questions: 115
Worksheet time: 2hrs 55mins
A synchronous motor controller will start the motor as induction motor and then
bring it into synchronization using dc excitation.
run it as a synchronized DC motor.
synchronize the stator with the line frequency.
synchronize the power factor and frequency.
The schematic below shows which of the following motors?
Series
Shunt
Compound
3-phase
The rotation of a 3-phase motor can be reversed by
moving all three leads in sequence
a multiple winding
reversing two leads
reversing the rotor resistance
Dynamic braking is used to
regulate the speed of a motor
mechanically slow the motor down
electrically retard or slow down a motor
derate the motor's horsepower
In a DC shunt motor, the speed can be increased above the base speed by
decreasing the field current
decreasing the armature current
shifting the brush neutral
increasing the strength of the shunt field
Why are interpoles installed in shunt and compound motors?
reduce or prevent sparking
reduce armature current
reduce the size of the main fields
increase the torque
The schematic below shows which of the following motors?
series
shunt
compound
3-phase
The schematic shows which of the following motors?
series
shunt
compound
3-phase
For normal starting of motors, the bimetallic element of a circuit breaker provides the required
temperature correction
time delay
varying current
voltage variation
Why is an anti-plugging relay used on a motor control panel?
To permit the motor to be jogged
to prevent the motor from being jogged
to prevent the motor from being hard reversed
to permit the motor to carry an overload for a short time
The direction of rotation of a DC motor wil change if the
armature and field current are reversed
amount of armature current is sufficiently decreased
amount of field current is increased
direction of armature current is reversed relative to its field
Read the motor tag below. What is the expected full load amperage when the motor is wired for use on a 480 volt service?
17.5
15.2
7.6
1.0
A generator converts
electrical energy into mechanical energy
electrical energy into heat energy
heat energy into electrical energy
mechanical energy into electrical energy
On large horizontal AC and Dc motors, plain babbitt bearing are needed to support the weight of the armature. the bearings are lubricated with oil rings. The oil rings
are grooves in the bearing that allow oil to reach all areas of the bearing
side on the bearing, supplying lubrication
must always rotate with the motor shaft, carrying oil to the bearing
ride on the ends of the bearings, keeping the lubrication oil from leaving the bearing area
When a photoelectric sensor does not work, you should first
check the amplifier
measure the resistance across the cell
check the light source
check the relay
Zener diodes are most often in
amplifier circuits
voltage regulator circuits
oscillator circuits
flip flop circuits
The range of power dissipation that can be obtained in this circuit is
46 to 96 watts
288 to 576 watts
288 to 1152 watts
576 to 1152 wats
In an electronic circuit you would use regulation
as a filter
to maintain a constant voltage at the load
to change capacitance
as a transformer
In a closed loop servo, a tachometer generator would be used to provide
speed feedback
supply position feedback
current feedback proportional to load
constant speed
A solenoid valve may be described as
a proportional control valve
slow
an on-off control valve
too small to use as a control valve
What type of output does a thermocouple generate?
millivolts
milliamps
pulses
BTUs
Which of the following is the symbol for current?
EMF
KV
I
KVA
Which of the following is a temperature switch?
Using the schematic below, what would cause the MX2 relay to de-energize?
tank is empty
overload contacts are open
start button is released
power loss on wire 109A15D
The purpose of the unit represented by the symbol is to
convert AC to DC
change voltages
measure power
limit current
The symbol for a DC shunt motor is
Which of the above symbols is a limit switch?
4
5
6
7
8
Which of the above symbols is a stop switch?
1
2
3
4
5
Which of the above symbols is a start switch?
2
3
4
5
6
Which conveyor must be started first in order to run all conveyors?
M1
M2
M3
Any one of the conveyors
In the circuit above, at what points should your voltage tester be placed to check the stop button?
X1 and 7
X2 and 1
4 and 7
2 and X2
Identify X2 in the diagram above
transformer
contactor coil
ground
primary winding
Identify a normally closed contact in the diagram above
X1 and X2
2 and 3
3 and 4
4 and 5
When overcurrent relays operate without intentional time delay, the type of protection is
inverse time
definite time
indirect acting
instantaneous
Which of the symbols below is a flow switch?
A
B
C
D
E
Electrical contacts in a thermostat must be small and, therefore, they cant handle the supply of current to a motor. The heavier current would be controlled through a
transformer
relay
shunt
switch
The core material in a Dc relay consists of
a coil of copper wire
a permanent magnet
soft iron
laminated plastic
If the primary coil of a transformer has more turns than the secondary, it is a
step-down transformer
step-up transformer
variable transformer
fixed transformer
During Lowering, which resistor is used for armature current limit and for dynamic braking when stopping?
R7-R8 & R8-R9
R8-R9
R1-R2
R20-R21
Which of the following will indicate if contactors move freely and close properly?
lubricating them
meggering them
operating them by hand
blowing them out with dry air
A 480 volt 3-phase service can be converted to 120 volt/phase for a control circuit by use of
a rectifier
a rheostat
a transformer
resistors
In the Diagram below, if 7R41 resistor opens, what would happen?
Nothing
hearth rolls would slow down
process section would slow down
hearth rolls would speed up
Which of the following devices will isolate a controlling circuit from a controlled circuit?
an SCR or a resistor
a relay
a transistor
a diode
To properly turn off an SCR once it is conducting,
remove the gate signal to turn it off
use a high speed contactor in series with the anode
reverse bias the anode with respect to the cathode
reverse bias the gate with respect to the cathode
To increase the PIV (Peak Inverse Voltage) ability of an SCR circuit (power rectifier),
connect two SCRs in series
increase the snubber capacitor value
decrease the snubber resistor
parallel to anode inductive reactances
In a full wave reversing the SCR bridge rectifier package with diodes connected to a three-phase delta transformer, what is the maximum number of SCR's required?
12
6
3
1
In the circuit shown below, the main function of the R component is to
filter output voltage and current
discharge the capacitors when turned off
balance the load
reduce the load on the rectifier
In a power transformer, the phase differential relay is used to
control output power
determine the policy to secondary voltage
protect the transformer in case of overload on any phase
protect the transformer in case the total current input vs total current output in any phase is different
How many volts of secondary voltage does the 220-440 V/110-220 V transformer have when connected as shown below
20
110
220
440
What is the correct use of a current transformer?
control circuit power
limiting current
metering
lighting
Short circuits in any system are always accompanied by a sudden
voltage decrease
current decrease
voltage increase
resistance increase
Given the AC sine wave voltage shown, what is the value of the RMS (Root Mean Square) Voltage?
10V
20V
7.07V
14.14V
Total opposition to current flow in an AC circuit is expressed as the
amperes
flux density
reaction
impedance
According to the electron theory, a flow of current is a movement of
protons from atom to atom
electrons from atom to atom
the nucleus around the atom
molecules within an atom
If the current is 12 amperes and voltage is 15 volts, what is the resistance?
.75 ohms
.80 ohms
.90 ohms
1.25 ohms
If the voltage is 115 volts and resistance is 20 ohms, what is the current?
5.75 amps
57.5 amps
230 amps
2300 amps
What is the current flow through the 3 ohm resistor in the circuit below?
1.3A
4A
6A
8A
What two factors change the speed of an AC induction motor?
size and direction
current and direction
resistance and current
number of poles and frequency
In normal operation, the voltage drop across a forward-biased silicon diode is
0.0V
0.7V
proportional to current through the diode
dependent on the applied voltage
A resistor that is color coded orange, orange, and brown has a resistive value of
22
330 ohms
44K ohms
2k Ohms +/-5%
Choose the answer that expresses Ohm's Law
R = E^2I
R = E/I
R = EI
I = ER
What should be used to convert AC to DC current?
transformer
bridge rectifier
shunt wound motor
conversion module
The ampere is the measure of
current
voltage
power
resistance
The watt is the measure of
current
voltage
power
resistance
A transformer has 400 turns in the primary and 200 turns in the secondary. If 240 volts are applied to the primary winding, what voltage will be measured on the secondary winding?
400V
240V
220V
120V
To prevent damage to a current transformer, the secondary winding must be
open
disconnected
short-circuited
insulated
What is the smallest control transformer requirement for a secondary full load of 11.2 Amps at 120 volts?
1 KVA
0.75 KVA
2.0 KVA
1.5 KVA
What device automatically or manually stops current flow under trouble conditions?
time delay fuse
control relay
circuit breker
circuit checker
A current transformer rated 2000/5 means
2000 volts through the primary of th current transformer will produce 5 volts in the secondary
the current transformer is rated for use on a 2000 volt circuit
a current transformer does not have a rating
the current transformer will produce 5 amps on the secondary if 2000 amps is passed through the primary of the current transformer
A potential transformer is used for
metering and relaying on a high voltage AC system
determining the current flow on an AC system
fuse protection for overloads
prevention of eddy current
A dual element fuse is used to
operate at higher voltage
operate at higher current
operate with a temporary overload
protect the transistor
Percentage differential relays compare the
incoming current to the outgoing current
outgoing currents on each feeder
incoming current to the bus tie
outgoing currents to the bus tie voltage
In power transmission, a transformer is used to raise the voltage on the sending end and lower the voltage on the receiving end in order to decrease
corona loss at towers
insulator length on units
eddy currents in breakers
wire size of power lines
Because of the manner in which a voltmeter is used, it must have
low resistance
high resistance
a multiplier in parellel
a movement that indicates plus and minus values
In the diagram below, what would the ammeter reading at "A" equal?
1/2 of B
2 times that of B
(A + B) / 2
the total current of the circuit
To see a picture of a particular point in a circuit you would use
a voltmeter
a frequency generator
an oscilloscope
a frequency counter
The accuracy of a volt-ohm-milliammeter is given as 2% of full scale. On the 10 volt range this would allow for an error of how many millivolts at full scale?
0.2 mV
0.02 mV
0.002 mV
200 mV
What is most harmful to the human body?
current
high votlage
high resistance
reactance
An "infinite" (10 megaohms or more) reading on a solenoid shows
a good solenoid
a grounded solenoid
an open solenoid
a short-circuited solenoid
The potential required to operate a megohmmeter is usually supplied by
a current transformer
the circuit being tested
a potential transformer
an internal power supply
The purpose of a megger is to measure
power factor
current
resistance
megawatts
Power in a circuit can be measured using a
voltmeter
wattmeter
ohmmeter
ammeter
What coupler would allow the greatest flexibility?
rigid shaft coupler
chain coupling
gear coupling
rubber mounted coupling
What information is needed to calculate the force that a hydraulic cylinder can exert?
diameter of inlet pipe
piston stroke
flow rate
hydraulic pressure (psi)
If a cylinder has an input pressure of 50 PSI and the BLANK SIDE of the piston is 5 sq. inches, how much total force is applied by the piston?
5 lbs
10 lbs
50 lbs
250 lbs
What is the most important use of oil film lubrication?
separate moving surfaces
prevent corrosion
increase pressure
increase friction
The viscosity of an oil is affected most by
contamination
resistance to corrosion
pressure
temperature
When metal parts are "seized" because of lack of lubrication, it is due to
expansion of the metal
contraction of the metal
contraction of the lubricant
expansion of the lubricant
In the diagram below, each circle represents a gear which can rotate about its own axis. If gear A is driven in a clockwise direction, which direction will gear C rotate and what will be its speed in reference to gear A?
clockwise and slower than A
clockwise and faster than A
counterclockwise and slower than A
counterclockwise and faster than A
What is the reason that an oxygen gauge reads "use no oil"?
oil causes the brass gauge to corrode
oil and oxygen make an explosive mixture
soap is a better lubricant
oil would gum up the mechanism
With E-stop in normal run position, which input must be "on" to start the motor?
10012
10020
10025
10067
Which of the following PLC input operations requires a conversion to digital form prior to input?
disc
analog
contact closures
limit switches
If a programmable controller controls the operation of a motor, what connects the motor to the PLC?
RS232 cable
Line voltage
I/O device
Modem
Computer software is
printer paper
computer programs
a soft keyboard
a computers wiring harness
If you had a flow transmitter that had a 4-20 mA mode output and a recorder that only accepted a 1 to 5 VDC input, what size resistor would you use on the input of the recorder to accommodate the mA signal?
25 ohms
40 ohms
250 ohms
400 ohms
Computer memory capacity is usually measured in terms of
volumes
bytes
electrical impulses
watts
A PLC system experiences a problem where a particular device connected to a 120Vac solid state output card remains energized at all time. An on-line examination of the ladder logic indicates that the output logic bit for that particular output is turning off and on as it should. All the other outputs connected to the card appear to be working. The device wiring shows no opens or shorts when an ohmmeter is connected to the wiring while it is disconnected from the output card. Which of the following procedures would most likely correct the situation?
replace the PLC processor card
replace the output card
reload the PLC memory
replace the output device
What tap is best to cut threads near the bottom of a blind hole?
centering tap
plug tap
bottoming tap
taper tap
If an indicator is not available, alignments between shafts can be checked with a
rule
chalk line
straightedge and feelers
square
When repairing a machine, you should
shut off the main source of power
shut off and lock the main source of power
use the on-off switch on the machine
instruct the operator to shut off the machine
Mark the letter of the correct reading for the micrometer in thousandths
0.04125
0.40125
0.412
4.125
When threading conduit on a pipe machine, cutting oil is used to
lubricate the drive motor on the pipe machine
prevent the chips from the threading of the conduit from blowing on the floor
prevent the formation of rust on the threads of the conduit after installation
cool and lubricate the die during the threading operation
If a fuse blows when the start button is pressed, what should you check for?
shorted motor circuit
open coils
grounded fuse holder
open neutral
In a step-down 3-phase transformer with no terminal markings, what would indicate the low voltage winding outputs?
the diameter of the wires sticking out of the transformer
the top wires are always on the high side of the transformer
the level of the insulating fluid since the high side is normally not in the fluid
if the transformer is a delta to delta, the center tap is on the secondary or low voltage side
When a Dc shunt motor does not come up to speed, the
field is too strong or the motor is oversized
field is too strong or the motor terminal voltage is too low
motor is oversized
motor terminal voltage is too low or the motor is oversized
What will happen to a DC compound motor without field loss protection if the shunt field coil opens while the motor is running under light load?
it runs faster
it runs at the same speed
it runs slower
it stops
What should you test before putting into service a wet motor which has been dried out?
voltage rating
winding resistance
insulation resistance
current required
In the case of a fire in a switch room, what kind of extinguisher should be used?
ABC type
hydrogen gas
foam type
water
An amp clamp (for example, Amprobe) should be placed around
one wire
two wires
three wires
the power wire and neutral
From a 900 ton production run, 90 tons were found to be defective. The precent defective is
5%
10%
15%
20%
An inexperienced electrician notices that the secondary voltage on a 480 volt distribution transformer is 510 volts. He is concerned because the one he checked last month was 461 volts. You explain to him that although both voltages are within the voltage tolerance established by NEMA,
the actual terminal voltage depends on plant incoming voltage and local load-center load. taps on both transformers are probably correct
the taps on both transformers should be adjusted immediately to get 480 volts on the secondary
transformer reading 461 volts should be adjusted to get closer to 510 volts
the lower voltage transformer should be inspected for shorted turns or other faults
The purpose of an arc chute over a contractor on a panel board is to
keep the dirt away from the contactor
keep the contactor aligned
protect your eyes
help extinguish the electric arc
What is the maximum number of 90 degree bends which should be used in a run of conduit between points where the wire can be pulled?
4
1
3
6
It is permissible to run instrumentation cables
with 4160 volt cable without dividers
with control cable without dividers
in separate steel conduit
in disconnected trays
How many feet of conduit may be run before a fitting or a pull box is required?
15 feet
50 feet
75 feet
100 feet
