Electric Motor Controls BOMA Pre-Quiz

Transcription

1 Electric Motor Controls BOMA Pre-Quiz Name: 1. How does a U.P.S. (uninterruptable power supply) work? A. AC rectified to DC batteries then inverted to AC B. Batteries generate DC power C. Generator, batteries, and AC power supply D. ATS to main bus 2. Batteries energy capacity is measured in. A. KVA B. Watts C. Amp-hours D. Volts 3. Batteries have two rated values: A. Amp-hours and Capacitance B. Capacitance and Voltage C. Watts and Coulombs D. Voltage and Amp-hours 4. How to you top off water in a battery cell? A. Distilled water when the level is below the plates. B. Soft water when the level is below the plates. C. Distilled water when the level is still above the plates. D. Soft water when the level is still above the plates. 5. A voltage monitor relay is used for: A. Starting backup generators. B. Fire system pumps. C. The building automation system HMI. D. Holding circuits. 6. Fuel for diesel generators is often stored in a: A. Flash tank B. Day tank C. Surge tank D. Circulating tank 7. converts between electrical and mechanical power. A. Motor B. Generator C. Alternator D. All of the above

2 8. The Field Winding on a generator. A. Is required by OSHA. B. Produces the magnetic field. C. Is also know as the brushes. 9. The stationary member of a generator is called a A. Rotor B. Stator C. Field D. Phasor 10. A motor A. Operates with 2-phase power supplies. B. Requires pulleys and belts. C. Converts mechanical energy into electrical energy. D. Converts electrical energy into mechanical energy. 11. An armature is: A. The stationary part of a motor. B. Is the coil mount. C. The movable portion of a contactor. D. A chair with arms. 12. In a process control, delay is: A. The time it takes for a change in the process to be felt. B. The time it takes to measure a process. C. The time it takes a technician to respond. D. The inverse of dally. 13. What is the difference between a contactor and a starter?: A. A starter has overload protection. B. A contactor has overload protection. C. A starter starts the motor and a contactor keeps it running. D. Contactors are electrical and starters are mechanical. 14. How is a holding circuit wired? A. Stop pushbuttons I series. B. Start pushbuttons in parallel. C. Using a holding contact.

3 15. What protects circuits from short circuits? A. Breakers B. Overloads C. GFCIs 16. Soft-starts work by: A. Lowing voltage during start up. B. Putting a brake on the motor. C. Starting during off-peak D. Lowering the powerfactor. 17. When a starter has a buit in disconnect, we call it a: A. Dual Starter. B. General purpose Starter. C. Combination Starter. 18. Normally closed means: A. There is no continuity when the component on the shelf. B. There is continuity when the component is on the shelf. C. We should close the device when not monitored. D. The position we would likely find it operating in. 19. What is an example of a P.E. switch? A. Pressure operated electric switch B. Electric operated pneumatic switch C. Solenoid valve D. Potential electric switch. 20. The input and output power of a transformer is rated in: A. Volts B. Amps C. Farads D. KVA 21. A soft start is used to: A. Reduce starting current. B. Control Speed. C. Increase torque. D. Keep old motors operating.

4 22. AC motors speed is determined by: A. The number of poles B. The supply voltage C. The supply current D. The interpoles connected to the armature 23. DC arcs. A. Are also known as 3-phase. B. Are the most difficult to extinguish. C. Are less damaging to equipment. D. Are also known as combination arcs 24. Arc chutes. A. Provide high circuit resistance when starting a motor. B. Help confine the arcs. C. Are found in most high KVA transformers. D. Are dangerous and violate the National Electrical Code (NEC) 25. The lower the NEMA rating on a contactor: A. The higher the current it can handle. B. The lower the current it can handle. C. The higher the voltage it can handle. D. The lower the voltage it can handle. 26. The current rating of a contactor: A. Is the max total current on all phases. B. The max current for each contact. C. The max current the coil draws. D. The max current divided by three. 27. A contactor with two sets of contacts is: A. A combination contactor B. Conventional C. 2-pole contactor D. A single phase starter 28. How do overloads protect a motor? A. By moving in the stator. B. Reducing an excessive magnetic field. C. Preventing stray or random current surge. D. Preventing excessive heating effects of high current. 29. A double-break contact's function is to reduce the voltage of each arc. A. True B. False

5 30. Overloads which have a delay in reacting to high current is: A. For sustained running times B. To prevent tripping during the starting period C. For fluctuating motor loads. D. Assist in motor shut down. 31. What is used when it is necessary to control a high power or high voltage circuit with a low power circuit A. Transformers B. Three-phase C. Relays D. Motor disconnects 32. Time delays on ATS systems can be done by using. A. Fluctuating current B. Fluctuating voltage C. Oil dashpots D. Quick/slow/quick scheduling 33. What consist of an electromagnetically inductive coil, wound around a movable steel or iron slug? A. Solenoid B. Permanent magnet C. Switch D. Contactor 34. A latching circuit consists of: A. Start and stop pushbuttons. B. And, or, not and nor logic. C. Solid state relays and a BAS D. Mechanical locking mechanisms. 35. The smallest size motor starter is: A. NEMA rating 120 B. NEMA rating 1 C. NEMA rating 0 D. NEMA rating Providing isolation from hazardous voltages and preventing starting by partial ground faults can be done by using. A. Soft-starts B. Three-phase C. VFDs D. Transformers

6 37. When a remote control is to be needed for an electrical motor, we could use: A. A latching circuit. B. 3-wire control. C. A maintaining circuit. 38. In a reversing motor starter we can prevent simultaneous energization of forward and reverse: A. Using Mechanical interlocks. B. Using the proper resets. C. Using a disconnect which is required by code. D. Using start and stop pushbuttons. 39. Single-phase, split-phase motors can be reversed by: A. Changing the electrical connections. B. Cannot be reversed. C. Changing both the start and running leads. D. Changing the brushes. 40. Which are designed to protect against short circuits? A. Overloads B. Fuses C. Control power transformers D. All of the above 41. Which are designed to protect motors from drawing too much current? A. Overloads B. Fuses C. Circuit breakers D. Disconnects 42. A sticky armature in a contactor will most likely: A. Weld the contacts together. B. Not cause any problems. C. Burn out the coil. D. Cause the contacts to bounce. 43. Opening the contacts under load: A. Causes damage to the contacts. B. Is the ideal condition. C. Is never nessisary. D. Can burn out the coil.

7 44. A fuses interrupting capacity is based on: A. The application it is used in. B. The maximum amperage it can interrupt without being damaged. C. Manufacturers design. 45. What is the circuit interrupt capacity of most fuses? A. 10,000 amps B. 20,000 amps C. 200,000 amps D. Depends on the application. 46. Drum switches reverse motors by swapping leads in a 3-phase system. A. True B. False 47. When several pushbutton stations are use in a sealing circuit, wire connections should have: A. Start buttons are in parallel B. Holding contacts in series with start buttons C. Stop buttons in parallel 48. Being wired across the line refers to: A. A dangerous wiring practice. B. A circuit that automatically restarts after power failures. C. Any rung in a ladder diagram. D. A solid wire with no physical cuts. 49. Unbalanced power systems is most likely caused by: A. Three phase motors. B. The power company. C. Single-phase loads being added. D. Bad capacitors. 50. When taking an Ohm reading A. Ensure there is adequate voltage. B. Isolate the circuit from the power supply. C. LOTO is not often required. D. Arc flash is the biggest hazard. 51. Most motor failures is caused by: A. Insulation on winding breaks down. B. Bearing go bad. C. Being defective from the factory. D. Plant vibrations.

8 52. A component that has high resistance in one direct and low in the other is a: A. Rheostat B. Capacitor C. Thermistor D. Diode 53. Single phasing is a term referring to: A. An older installation without a grounding wire. B. Transforming three-phase into single phase. C. Losing one phase on a two-phase circuit. D. Losing one phase on a three-phase circuit. 54. Improper alignment of the pole faces in a solenoid: A. Is the primary cause of power surges. B. Will open the valve. C. Can cause excessive humming. D. Is a direct code violation. 55. When a manual motor starter handle trips: A. It keeps running until manually changed. B. The handle moves to a mid-center position. C. The motor keeps running. D. An audible and visual alarm should sound. 56. Contacts excessively cycled: A. Is a method of cleaning the points. B. Causes the coil to overheat. C. Causes the contacts to overheat. 57. When resetting overloads: A. Wear arc-flash protection. B. Check the load for obvious problems. C. Replace the contactor. 58. When troubleshooting s system that does not operate: A. Check for obvious problems. B. Check the power source. C. Check that the controls are on.

9 59. If a fuse or heater on a three phase power system goes bad: A. You should replace all three. B. Replace only the bad one. C. Check for imbalanced phases. D. Switch to a single phase system. 60. Using a megger to get the winding resistance of a motor winding indicates: A. The age of the motor. B. The condition of the winding insulation. C. If the motor is improperly wired. D. The amperage of the motor. 61. When should you use a VFD? A. When the motor load fluctuates. B. When soft start is desireable. C. When starting large loads during peak hours. 62. A four-pole induction motor operates with a line frequency of 60 hz. What is the speed at which the field is rotating in revolutions per minute? A. 600 B. 900 C D The speed a three phase motor's field rotates is: A. Synchronous speed B. Field speed C. Armature speed D. Rotor speed 64. Torque is: A. Rotational work B. Force times distance C. Pressure on a round shaft D. Stress in changing directions 65. A 7200 rpm motor at 60hz has: A. Two poles B. Four poles C. Eight poles D. Does not exist

10 66. What determines the speed of a synchronous motor? A. Voltage B. Amperage C. Rotor size D. Poles 67. Opposite poles of a magnet will: A. Repel B. Attract C. Act different depending on the wire connections D. Create rotary motion 68. A magnetic field: A. Is created when current flows. B. Surround a magnet. C. Is invisible. 69. A temporary magnet is: A. A loadstone. B. A rare earth magnet. C. An electromagnet. D. A bar magnet 70. What is required to create an electromagnet? A. Wire B. Electricity C. Coil 71. 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. 72. If a motors rotor locks: A. Overloads should open. B. Breakers should open. C. Fuses should open.

11 73. Poor motor ventilation / clogged vents would likely cause: A. Fuses to blow. B. Excessive humming. C. Motor overheating. D. None of the above. 74. A defective starter would likely not cause: A. Damaged bearings B. Excessive vibrations C. High voltages 75. 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. 76. The overload protection protects: A. The branch circuit B. The motor C. The branch conductors 77. The operating period of an electrical device is known as: A. Turndown ratio B. Duty cycle C. Power factor D. LRA 78. 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. 79. 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

12 80. 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 81. How are normally closed contacts are indicated on a ladder diagram: A. NOC B. A circle C. Italics D. An underline 82. 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 83. The difference between the field speed and rotor speed is designated as: A. Brake horsepower B. Speed depression C. Slip D. Dynamic speed 84. have overloads and do not: A. Contactors, motors B. Starters, contactors C. Motors, overloads D. Contactors, starters 85. Branch circuit conductors, must be rated at least of the motor's full load current: A. 90% B. 100% C. 110% D. 125% 86. 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.

13 87. Imbalanced phases cause three-phase motors: A. To vibrate B. Rev up and down frequently C. To reverse D. To overheat 88. 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 89. Cross firing is: A. A shorted circuit-board B. Arcing across a double-brake contact C. Shorting from phase to phase D. Excessive jogging 90. The stator is attached to the: A. Armature B. Rotor C. Frame D. Shaft 91. 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 92. 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 93. 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

14 94. At a 60 hz frequency, a two-pole motor will operate at: A rpms B rpms C rpms D. 900 rpms 95. A device used to measure the rotating speed of a motor is called a: A. Accelerometer B. Transducer C. Timing light D. Tachometer 96. 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% 97. VFDs control the speed of a motor by: A. Changing the voltage. B. Changing the frequency. C. Changing the input to the motor. 98. Low voltage to a motor can cause: A. Energy savings B. Poor lubrication C. Overheating D. All of the above 99. 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 100. Polyphase means: A. More than one phase B. More than three phases C. Multiple sources making a magnetic field D. None of the above

15 Answers: 1. A 2. C 3. D 4. A 5. A 6. B 7. D 8. B 9. B 10. D 11. C 12. A 13. A 14. D 15. A 16. A 17. C 18. B 19. A 20. D 21. A 22. A 23. B 24. B 25. B 26. B 27. C 28. D 29. A 30. B 31. C 32. C 33. A 34. A 35. D 36. D 37. D 38. A 39. A 40. B 41. A 42. C 43. A 44. D 45. D 46. A 47. A 48. B 49. C 50. B 51. A 52. D 53. D 54. C 55. B 56. C 57. B 58. D 59. A 60. B 61. D 62. D 63. A 64. B 65. D 66. D 67. B 68. D 69. C 70. D 71. B 72. A 73. C 74. D 75. A 76. D 77. B 78. A 79. A 80. B 81. D 82. D 83. C 84. B 85. D 86. B 87. D 88. A 89. B 90. C 91. A 92. B 93. C 94. A 95. D 96. C 97. D 98. C 99. A 100. A