Question 1
You are asked to connect a single-phase motor according to its nameplate. Which piece of information is most critical for selecting the correct overload protection?
Question 2
A motor starts normally, runs for several minutes under load, and then trips on the overload relay. What is the MOST likely cause?
Question 3
Which information on an induction motor nameplate is MOST important when selecting an overload relay setting?
Question 4
A motor repeatedly trips its thermal overloads after several minutes of operation under normal load. Which is the MOST appropriate initial action?
Question 5
A three-phase motor is tripping overloads shortly after starting under normal mechanical load. Voltage is correct and balanced. What is the next best step?
Question 6
An MCC bucket contains a combination starter with fuses, a contactor, and an overload relay. Which component provides protection against long-term overloads of the motor?
Question 7
On a motor control schematic, a dashed line connecting an overload relay to the contactor coil typically indicates:
Question 8
What is the primary function of a thermal overload relay in a motor starter?
Question 9
Which device is specifically designed to protect a motor from overload conditions rather than short circuits?
Question 10
A motor nameplate shows a full-load current of 9 A at 240 V. If the measured running current is 13 A under normal load, what is the likely issue?
Question 11
A three-phase motor is connected in a control circuit using a contactor and overload relay. What is the main purpose of the overload relay?
Question 12
What is the primary function of a motor overload relay installed in a motor starter?
Question 13
Why are overload relays installed in motor starters?
Question 14
A motor nameplate indicates a full-load current of 9 A at 240 V. The overload relay is to be set at 125 percent of full-load current. What should the relay setting be?
Question 15
When sizing overload protection for a motor with a Service Factor (SF) of 1.15, what is the maximum percentage of Full Load Amps (FLA) typically allowed by code?
Question 16
When sizing the overload for a motor with a 1.0 service factor, what is the maximum setting allowed?
Question 17
When selecting overload protection for a motor with a Service Factor (SF) of 1.15, what is the maximum setting allowed by CEC concepts?
Question 18
Which component in an industrial motor starter provides protection against a persistent current that is slightly above the motor's rated full-load current (FLA)?
Question 19
Which of the following BEST describes the function of overload relays in a motor starter?
Question 20
In a motor control circuit, what is the primary function of an overload relay installed with a contactor?
Question 21
A 3-phase, 600 V, 30 hp induction motor in an industrial plant is tripping its overload relay after running under a heavy process load for 20 minutes. Measurements show balanced line currents slightly above full-load current, and the supply voltage is within 5% of nameplate. What is the most appropriate first step?
Question 22
In a control circuit, what is the effect of wiring a normally closed overload relay contact in series with the contactor coil?
Question 23
You are troubleshooting a three-phase motor that repeatedly trips its overload relay shortly after starting. Line voltage is correct and balanced. Which issue is most likely?
Question 24
In a magnetic motor starter, what is the primary function of the overload relay?
Question 25
A motor control centre (MCC) feeds several induction motors. One motor repeatedly trips on thermal overload after a process change that increases mechanical load. Voltage and current are within nameplate values, but the motor operates near full-load current continuously. What is the most appropriate corrective action?
Question 26
A 10 hp, three-phase motor repeatedly trips its overload relay during startup, but the fuses do not blow. What is the most appropriate first step?
Question 27
An industrial control panel shows that a motor overload relay is tripping frequently while the breaker does not trip. What does this typically indicate?
Question 28
You are troubleshooting a motor that occasionally trips its overload relay but never trips the short-circuit protective device. Which condition is most likely causing this problem?
Question 29
A facility is converting from individual starters to a PLC-based motor control system. Which issue must be carefully considered when transferring overload protection?
Question 30
Which component is commonly used to provide overload protection for an AC induction motor in a motor starter?