Name: Werner Jefferson Barrios Zepeda ID: 2012-12584
Date: 10/06/2020 IT3
Worksheet No. 5
I part
Answer the following question. You must investigate
What is required to create an electromagnet? A. Wire B. Electricity C. Coil D. All of the above.
1. A magnetic field is created when?
a. Copper is in a coil.
b. Electricity flows.
c. You have a ferrous metal.
d. You have two SPST switches in series.
2. If a motors rotor locks:
a. Overloads should open.
b. Breakers should open.
c. Fuses should open.
d. All of the above.
3. Poor motor ventilation / clogged vents would likely cause:
a. Fuses to blow.
b. Excessive humming.
c. Motor overheating.
d. None of the above.
4. A defective starter would likely not cause:
a. Damaged bearings
b. Excessive vibrations
c. High voltages
d. All of the above.
5. If a motor is running hot:
a. Check the amperage.
b. Cool the room using more ventilation.
c. Running it at a slower R.P.M.
d. Try reversing the leads.
6. The overload protection protects:
a. The branch circuit
b. The motor
c. The branch conductors
d. All of the above.
7. The operating period of an electrical device is known as:
a. Turndown ratio
b. Duty cycle
c. Power factor
d. LRA
8. A “ladder rung” in an electrical diagram refers to?
a. A single line in the diagram
b. The type of ladder you may use while working on that circuit
c. A series of switches and buttons
d. An open contact.
9. This is the logic function that says both inputs must be true for the output to occur:
a. And
b. Or
c. Not
d. Nor
10. Interlocking is:
a. When two devices are completely independent from each other.
b. When one devices position is dependent on another devices position.
c. The highest function of Lockout-Tagout (LOTO)
d. Using multiple keys when performing LOTO
11. How are normally closed contacts are indicated on a ladder diagram:
a. NOC
b. A circle
c. Italics
d. An underline
12. An electrical motor's nameplate:
a. Must indicate the year they were built
b. Must indicate the year they were installed
c. Must indicate type X or Y
d. Must be on every motor in the plant
13. The difference between the field speed and rotor speed is designated as:
a. Brake horsepower
b. Speed depression
c. Slip
d. Dynamic speed
14. _______have overloads and _________ do not:
a. Contactors, motors
b. Starters, contactors
c. Motors, overloads
d. Contactors, starters
15. Branch circuit conductors, must be rated at least ______ of the motor's full load current:
a. 90%
b. 100%
c. 110%
d. 125%
16. Three-wire circuits:
a. Are for three-phase
b. Require a contactor or relay
c. Can “singlephase”
d. Are said to be wired across the line.
17. Imbalanced phases cause three-phase motors:
a. To vibrate
b. Rev up and down frequently
c. To reverse
d. To overheat
18. Thermal overloads:
a. Protect motors from overcurrents
b. Protect motors from single-phasing
c. Protect motors from excessive loads
d. Protect motors from three-phasing
19. “Cross firing” is:
a. A shorted circuit-board
b. Arcing across a double-brake contact
c. Shorting from phase to phase
d. Excessive jogging
20. The stator is attached to the:
a. Armature
b. Rotor
c. Frame
d. Shaft
21. Reversing a DC motor requires:
a. Reversing the direction of electricity flow.
b. Using an SPST switch
c. Using a PE switch
d. Any of the above
22. Silicon-controlled rectifiers (SCRs):
a. Is another term for Rheostats
b. Are used as DC drives
c. Require changing electrodes for different applications
d. Are three-phase drives
23. A tachogenerator:
a. Is another term for Rheostats
b. Is a full bridge rectifier
c. Generates a voltage based on speed.
d. Is for open loops
24. At a 60 hz frequency, a two-pole motor will operate at:
a. 3600 rpms
b. 2700 rpms
c. 1800 rpms
d. 900 rpms
25. A device used to measure the rotating speed of a motor is called a:
a. Accelerometer
b. Transducer
c. Timing light
d. Tachometer
26. An induction motor will develop maximum torque at what speed?
a. 25% to 50%
b. 50% to 60%
c. 70% to 80%
d. 90% to 100%
27. VFDs control the speed of a motor by:
a. Changing the voltage.
b. Changing the frequency.
c. Changing the input to the motor.
d. All of the above.
28. Low voltage to a motor can cause:
a. Energy savings
b. Poor lubrication
c. Overheating
d. All of the above
29. If the motor and starter are installed in locations with different temperature conditions:
a. The heater selection will be affected
b. You should use larger wires
c. Air-conditioning should be installed
d. 3-wire circuits are required
30. Polyphase means:
a. More than one phase
b. More than three phases
c. Multiple sources making a magnetic field
d. None of the above
