Book #3 Flashcards
(41 cards)
When installing a switched receptacle in a residential bedroom, what must be done so the receptacle can also be counted as a wall outlet?
Constant power on the top socket
When the liquid level is down in a battery, what type of liquid do you add?
Distilled water
On a single-phase split-phase induction motor, the centrifugal switch disconnects the start winding from the circuit at what percentage of the full speed of the motor
75%
What characteristics will a capacitor-start motor have?
Low inrush current and high starting torque
In a DC circuit, Voltage and Current are:
Directly proportional
Where do you find the maximum amount of area a smoke detector covers?
The manufacturer
During a routine maintenance check of a wye connected 3-phase motor, you discover when you take individual amp reading of each phase that one phase is drawing 7 amps more than the other. what is the probable cause
Shorted winding
What is the main reason for lubricating bearings in a motor?
Reduce heating
What is the proper procedure to follow when energizing an oil-filled transformer for the first time?
Open the secondary and energize the primary
When wiring a control system, how shall normally closed devices be wired?
in series
What is the installation requirements for single conductor mineral-insulated cables carrying over 425A?
Grouped together to minimize induced sheath currents
Most AC voltmeters and ammeters are calibrated in?
Root-means-square values
The hypotenuse of the power triangle represents:
Apparent power
The primary purpose of a megger is to measure:
Resistance
A Split-phase AC motor is made self starting by the addition of:
Starting winding
The primary of a current transformer is always connected in:
Parallel with the load
The primary hazards when handling and charging batteries is/are due to the danger of
Acid burns and explosions
“Trip-free” as applied to electrical terms means:
Mechanism which makes it impossible to hold contact close against overload
A motor can be operated as a generator when the motor needs to be slowed or stopped quickly. what is this type of DC motor control called?
Dynamic Braking
The purpose of electrical interlocks in a reversing magnetic starter are:
To prevent mote than one coil from being energized at the same time
Limit switches are usually used to limit:
Travel
A dual voltage single phase motor must have:
Two running windings
A dual voltage AC motor operating on the higher voltage will draw:
Less current than on the lower voltage
A single phase motor has a phase to ground fault, a possible cause is:
The centrifugal switch is touching the frame
