Question 1
A three-phase motor is supplied from a panelboard. One phase connection at the terminal box becomes loose. Which symptom is most likely?
Question 2
A 3-phase, 208 V panel supplies a 3-phase motor. Compared to a single-phase motor of the same horsepower, what is a typical advantage of using the 3-phase motor?
Question 3
You are troubleshooting a motor that hums but does not start. Voltage is present at the terminals, and the overload relay has not tripped. What is a likely cause?
Question 4
You are connecting a three-phase motor that can be wired in delta or wye. For a higher line voltage connection, which configuration is typically used?
Question 5
A three-phase motor frequently trips its thermal overload on startup but runs normally once up to speed. What is the most appropriate solution?
Question 6
A VFD (variable frequency drive) is installed to control a three-phase motor. What effect can VFDs have on the neutral conductor in a 3-phase, 4-wire system with other loads?
Question 7
A three-phase motor is running in the wrong direction. What is the usual corrective action?
Question 8
A three-phase, 208 V motor draws 28 A at full load with a power factor of 0.8. Approximately how much real power (kW) is the motor using at full load?
Question 9
A motor nameplate shows 230 V, 10 A, single-phase. What is the approximate full-load power in kilowatts assuming unity power factor?
Question 10
A 3-phase motor is running but making unusual noise and drawing higher than normal current on one phase. What is the most likely electrical issue?
Question 11
When connecting a small three-phase motor, which piece of information is most important to obtain from the motor nameplate?
Question 12
After reconnecting a three-phase pump motor, the electrician notices that the pump is running backwards. All voltages measure correctly. What is the proper corrective action?
Question 13
A variable frequency drive (VFD) is installed to control the speed of a three-phase motor driving a fan. Which consideration is most important when selecting the feeder and motor cables?
Question 14
Which type of braking method involves injecting DC current into the stator windings of an AC motor after the AC supply is disconnected?
Question 15
Which type of braking uses DC injection into the stator of an AC motor?
Question 16
Which DC motor type is prone to runaway if the field is lost?
Question 17
What is the typical nominal voltage supplied to a single-family dwelling in Canada?
Question 18
In a three-phase system, what is one key advantage over a single-phase system for supplying large motors?
Question 19
During commissioning, you observe that a 3-phase induction motor rotates in the wrong direction. What is the simplest corrective action?
Question 20
A three-phase 208 V panel feeds a mix of single-phase and three-phase loads. If single-phase loads are heavily concentrated on phase A, what is a likely consequence?
Question 21
Which of the following best describes a ring-type compression lug used on power distribution equipment?
Question 22
In a basic control circuit, a three-wire control station for a motor starter typically includes which combination of devices?
Question 23
A three-phase induction motor nameplate indicates a full-load current of 10 A. What is the main purpose of the overload protection for this motor?
Question 24
A Level 2 apprentice is asked to identify the symbol for a double-pole single-throw switch on a schematic. What characteristic should they look for?
Question 25
A 3-phase motor is nameplated 15 kW, 600 V, three-phase. What information on the nameplate is critical for selecting the correct overload relay setting?
Question 26
In a three-phase, 208 V system supplying a balanced motor load, what will typically happen if one phase conductor becomes open?
Question 27
A three-phase motor nameplate shows 9.6 A at 600 V. What is the approximate line current if the motor is fully loaded at rated voltage and power factor?
Question 28
A motor nameplate shows 230 V, 10 A, single-phase. Which of the following is the approximate full-load apparent power?
Question 29
A three-phase motor is running in the wrong direction after installation. What is the simplest corrective action?
Question 30
One advantage of a three-phase motor compared to a single-phase motor of the same rating is that it: