ELE 146 Exam
If a pressure switch is used to maintain a set pressure, are NO or NC contacts used to control the compressor motor starter?
NC
If a flow switch is used to detect flow in an automatic sprinkler system that has detected a fire and opened the sprinklers to flow, are NO or NC contacts used to control the alarm?
NC contacts
If a level switch is used in a charging system, are NO or NC contacts used to control the pump motor starter?
NC contacts
1. If a flow switch is used to sound an alarm when there is no flow, are NO or NC contacts used to control the alarm?
NO contacts
If a level switch is used in a discharging system, are NO or NC contacts used to control the pump motor starter?
NO contacts
If the moving part of a limit switch is drawn below the contacts in the symbol, is the switch NO/NO held closed or NC/NC held open?
NO: held closed NC: held open
Are reed relays usually used to switch loads in the 0.1 A to 10 A range?
Yes
Can a relay with multiple contacts use the different contacts to control different loads, each with a different voltage level, as long as each circuit is isolated from the other circuits?
Yes
Can one relay coil control several different relay contacts?
Yes
What does an electrical control valve use to change the position of a valve spool?
actuator
What is the movable part of a solenoid called?
armature
What are the two basic types of circuit protection devices?
circuit breakers and fuses
If the moving part of the limit switch is drawn above the contacts in the symbol, is the switch NO/NO held closed or NC/NC held open?
When NC is closed, NO will be held open
If a voltage is measured going into a control switch and no voltage is measured out of the switch, what operating conditions might the switch be in?
closed conditions
If a temperature switch is used in a cooling system to maintain a set temperature, are NO or NC contacts used to control the air condition system?
cooling systems use NO
If resistance is increased in a circuit, does current increase or decrease?
decreases
What are the two basic types of contactors?
energized and de-energized
What is the left-hand rule used to determine when the direction of current flow is known?
f the fingers of the left-hand wrap in the direction of current flow than the left thumb points towards the magnetic north pole of the coil.
Which type of diagram helps when troubleshooting because it shows a logical path to take that helps solve a problem?
flow charts
If a temperature switch is used in a heating system to maintain a set temperature, are NO or NC contacts used to control the heating contactor?
heating system is controlled using NC contact
When a pressure switch is rated in "in. WC," what does "in. WC" stand for?
inches of Water Column
Does the added iron core of an electromagnet increase or decrease the magnetic lines of force?
increases magnetic lines of force
What type of limit switch actuator allows the arm length to be adjusted to meet the application?
levers
. Which type of diagram shows the logic of an electrical circuit drawn with vertical power lines and circuit components drawn on horizontal lines between the power lines?
line diagram
If a voltage is measured going into a control switch and the same voltage is measured going out of the switch, what operating conditions might the switch be in?
open conditions
Which type of diagram shows physical details, such as the length and height of an object, as seen by the eye?
pictorial drawing
In a joystick symbol, what does the dot represent?
position where contact will close
What are the five parts of a basic electrical circuit?
power source, conductor, control switch, protection device, load
If a transformer has a turns ratio of 1:4, what is the transformer's voltage ratio?
the transformers voltage ratio would be the same as the turn ratio for this one. 1:4
What is a flow path through a valve?
way
If a transformer has a turns ratio of 1:4 and 115 V is applied to the primary, how many volts are on the secondary?
460 V.
What type (number) NEMA enclosure can be used to protect internal electrical components against prolonged submersion at a limited depth, such as occasional flooding of an area?
6P
Can one pushbutton operate both NO and NC contacts?
A pushbutton with a contact block can operate both NO and NC contacts
A disconnect is a switch that will:
Manually remove power from a circuit or apply power to a circuit
In a truth table, an X represents what condition of the contacts?
Closes condition in any position
What type of fuel is used to produce the most amount of electricity?
Coal
Contacts are used in:
Contactors
. What device allows current to flow in only one direction?
Diode
What type of contact is best to use when switching higher power loads?
Double Break
What does DPST-DB stand for?
Double Pole Single Throw - Double Break
What is the number of times a solenoid can operate in a given time period (usually operations per minute) called?
Duty Cycle
Voltage is measured in volts (V), but what letter is used to represent voltage?
E
Which particle has a negative charge?
Electrons
What are the three fundamental particles contained in atoms?
Protons, electrons and neutrons.
One application of interlocking is to cause both the forward and reverse coils of a reversing contactor to be energized at the same time.
False
If 230 V and 6.25 A are measured in a heating element, how much resistance (in Ω) does the heating element have?
36.8 ohms
What is the acceptable resistance range (high and low) that should be measured when testing a solenoid?
+- 15%
What is the acceptable voltage range (high and low) that should be applied to a solenoid?
+-10%
What is the number of locations within a valve in which a spool is placed to direct fluid through the valve?
2 maybe 3
If 12 V is applied to a circuit that has a resistance of 500 Ω, how many milliamperes (mA) will flow through the circuit?
24 milliamperes (mA)
A Hand-Off-Automatic (H-O-A) circuit requires a selector switch with __________ positions.
3
What electrical devices consume the largest share of produced electricity?
3 phase motors
. What are the two types of current?
Alternating and direct
Which of the following is not a rule of drawing a ladder diagram?
At least 2 loads per line
A form letter is used to simplify relay contacts. What form letter would identify a relay with a SPST-NC contact type?
B
Is a diode used to help protect electrical contacts in an AC or DC load switching circuit?
DC
What type of valve is used to direct the flow of fluid throughout a fluid power system?
DCV - Directional Control Valve
Why is a shading coil added to the armature of a solenoid?
Holds the armature as magnetic field approaches zero in an AC circuit
What position are most flow switches designed to operate in?
Horizontal Position
. Current is measured in amperes (A), but what letter is used to represent current?
I
. What is the IEC number used to describe the enclosure type that can be used to protect internal electrical components against prolonged submersion at a limited depth, such as occasional flooding of an area?
IP38
If the voltage applied to a solenoid is higher than the rating of the solenoid, will the current draw increase or decrease?
Increase
Which relay type comes with convertible contacts that can be placed in either an NO or NC operating position?
Industrial or Heavy Duty relays
What is the initial current draw of a solenoid called?
Inrush Current
What is the best type of pushbutton operator to use in an emergency stop application?
Jumbo Mushroom Button Operators
Are relays usually used to control higher current loads, such as a 20 A electric motor?
No
Can reed relays be manually operated?
No
Does the load (alarm, motor starter coil, etc.) that the relay contacts control need to be the same voltage rating and type (AC or DC) as the relays coil?
No
When a foot switch has three positions, does the toe usually operate all three positions?
No
In a 120 V circuit, is it acceptable when 2 V are measured across a closed contact operating a load?
No, <1V
Should relay contacts be filed when showing signs of wear?
No, always replaced
In a 120 V circuit, is it acceptable when the full 120 V are measured across an open relay contact?
No, relay will be defective and contacts will not close at maximum voltage
In electrical switches, what do the abbreviations NO and NC stand for?
O : normally opened, NC : normally closed
What unit is used to measure resistance?
Ohms
Who should remove a lock-out / tag-out?
Only the person who installed it
In a truth table, an O represents what condition of the contacts?
Open (open contact)
Resistance is measured in ohms (Ω), but what letter is used to represent resistance?
R
Why are gold-flashed silver contacts used in automobile air bag activation control systems?
Reduce chances of sulfidation & have a good electrical connection
What is the operating current of a solenoid called?
Sealed Current
A __________ is often used to allow an operator or technician to change a machine from the automatic mode to the manual mode.
Selector switch
If a transformer has a turns ratio of 1:4, what is the transformer's current ratio?
The transformers current ratio would be the reciprocal of turn ratio. 4:1
What are the two windings of a transformer called?
The two winding of a transformer are called Primary, and secondary winding.
A selector switch with a legend plate labeled SLOW/OFF/FAST is an example of what type of selector switch?
Three Selector Switch
Why are solenoid armatures laminated?
To keep them from chattering.
The contact shown in the figure is a(n) ___________ ?
True
When batteries are wired in Series, you are increasing the Voltage.
True
A selector switch with a legend plate labeled SLOW/FAST is an example of what type of selector switch?
Two Position Selector Switch
What is the main advantage of using a joystick in an application such as moving the passenger loading ramp to and from an airplane door?
Two advantages are being able to move the loading ramp forward or backwards based on your needs, and not having to remove your hands from the joystick nor your eyes from the task being preformed.
The measured unit of electromotive force is a __________.
Volt
To quickly determine if a circuit is hot, what is the simplest tool to use?
Voltage meter
. What type of limit switch actuator allows detection of a moving object from any direction except head on?
push roller
What device converts AC voltage to DC voltage?
rectifier
Which type of diagram uses symbols to show the interconnections of components in electronic circuits?
schematic diagram
What are the two types of AC voltage?
single phase AC, three phase AC
What device is used to reduce transients produced by solenoids?
snubber circuit
What electrical device converts electrical energy into a linear mechanical force?
solenoid
Is the OFF position of a foot switch usually a maintained position or a spring-loaded position?
spring loaded position
What electrical device is used to turn a motor on and off and includes overload protection?
starter
In an electromagnet, what determines the strength of the magnetic field?
strength of the current
. If a transformer has a turns ratio of 1:4, what is the transformer's power ratio?
the power ratio of the transformer would be 1:1