Question 31
In a motor control circuit, what is the primary purpose of an overload relay connected in series with the motor?
Question 32
A motor occasionally trips on overload at startup but runs normally when it does start. Which adjustment or correction is MOST appropriate to consider first?
Question 33
Which component in a motor starter assembly is designed to protect the motor from overload conditions rather than short circuits?
Question 34
An electrician notices that a motor control circuit intermittently drops out when nearby large motors start. Which corrective action is most appropriate?
Question 35
In a motor control ladder diagram, what is the primary purpose of a normally closed overload contact placed in series with the motor starter coil?
Question 36
In a three-phase motor control circuit, what is the purpose of an overload relay?
Question 37
A motor control center (MCC) feeds several large motors. One motor frequently trips its overloads while others on the same bus operate normally. Measurements show normal line voltage and balanced phase currents at rated full-load. What should the electrician investigate next?
Question 38
In a motor starter, what is the main purpose of the overload relay?
Question 39
What is one common advantage of using a variable frequency drive (VFD) on a three-phase motor driving a pump?
Question 40
A motor control center (MCC) bucket contains a combination motor starter with fuses and an overload relay. Which statement best describes the role of the overload relay?
Question 41
In a motor circuit, what does the term 'overload protection' refer to?
Question 42
What information on a motor nameplate is MOST useful for selecting the correct size of overload protection?
Question 43
A three-phase motor controlled by a magnetic starter runs for about 20 seconds and then stops, but voltage is still present at the control circuit supply. The overload relay's reset button is popped out. What is the MOST likely cause?
Question 44
A motor nameplate lists 230 V, 10 A, single-phase. Approximately what size of full-load current is used to select the overload protection setting?
Question 45
A 25 hp, three-phase, 480 V motor is being installed. The motor branch-circuit short-circuit and ground-fault protective device is sized according to code tables. Why is the motor overload protection typically set closer to the motor nameplate full-load current?
Question 46
A motor control center (MCC) has several combination starters. One motor frequently trips on overload even though measured running current is slightly below nameplate full-load current. Which condition is most likely causing the nuisance trips?
Question 47
In a motor control circuit, what is the typical function of an overload relay?
Question 48
You are troubleshooting a 3-phase motor that trips its overloads after several minutes of operation. Voltage is balanced, and no single-phase condition is found. What is the most likely next step?
Question 49
When setting an adjustable overload relay for a small three-phase motor, what guideline is typically followed for setting the trip current?
Question 50
A 10 hp, 480 V three-phase motor is protected by a standard thermal-magnetic breaker sized close to its full-load current. The breaker trips every time the motor starts, but the motor runs normally if the breaker is temporarily oversized under supervision. What is the best long-term solution?
Question 51
A motor starter includes an overload relay. What is the primary function of this overload device?
Question 52
A 10 HP, 208 V, three-phase motor is tripping its overloads shortly after starting while driving a conveyor. Voltage is correct and the conveyor turns freely by hand. Which action is most appropriate to investigate first?
Question 53
A motor control circuit includes an overload relay. What is the primary purpose of this overload device?
Question 54
A variable frequency drive (VFD) is installed to control a three-phase motor. Which effect is a common concern on the motor leads between the VFD and the motor?
Question 55
What is the primary function of a motor contactor in a control circuit?
Question 56
In a control circuit, what is a common use of a normally closed (NC) contact on an overload relay?
Question 57
A three-phase 208 V motor is drawing 18 A on phase A, 18 A on phase B, and 10 A on phase C under full load. What is the most appropriate first step in troubleshooting this imbalance?
Question 58
What is the primary function of a motor overload relay in a motor starter assembly?
Question 59
What is the primary function of an overload relay in a motor starter?
Question 60
What device is primarily used to protect a motor from damage due to mechanical overload or phase loss, separate from short-circuit protection?