Review sheets Flashcards
The rated or nameplate current of a motor?
full load current
the current drawn when a motor is stalled?
locked rotor current
another name for across-the-line starting?
full motor voltage start
a method of starting a motor with a lower value than rated line voltage?
reduced voltage start
a magnetic starter and fused safety switch within the same enclosure?
combination starter
the device in a magnetic starter which helps reduce contact chatter
shading coil
the part of the circuit associated with the auxiliary seal-in contact?
control circuit
a diagram which shows the general layout of the components and the interconnections?
wiring diagram
the part of a magnetic starter circuit which prevents automatic restarting after a power failure?
seal in contact
A shading coil in a magnetic starter is intended to:
a) maintain the starter in the closed position
b) produce faster response time
c) reduce arcing
d) reduce chatter
d) reduce chatter
Overload protection of a motor is provided by:
a) capacitors
b) bi-metal units and heaters
c) control transformers
d) breakers or fuses
b) bi-metal units and heaters
A magnetic blow-out coil:
a) reduces chattering of a starter
b) provides overload protection
c) limits motor starting current
d) aids in extinguishing the arc between contacts
d) aids in extinguishing the arc between contacts
When used, the holding/maintaining/ seal-in contact of a magnetic starter is:
a) in series with the stop button
b) in parallel with the stop button
c) connected across the holding coil
d) in series with the start button
a) in series with the stop button
In the case of a power failure, when a motor will not re-start after the voltage is re-established, is referred to as:
a) low voltage protection
b) line voltage starting
c) low voltage release
d) reduced voltage starting
a) low voltage protection
the purpose of an electrical interlock in a forward/reverse motor control circuit is:
a) to maintain the coil circuit
b) to prevent more than one starter a time from being energized
c) to provide plugging to stop the motor quickly
d) for activating indicating or pilot lights
b) to prevent more than one starter at a time from being energized
The control circuit, in across the line starters or forward/reversing starters, for 3Ø induction motors are :
a) 3Ø
b) 2Ø
c) 1Ø
c) 1Ø
A knife switch should be open quickly to:
a) reduce arcing at the contacts
b) save the operator time
c) prevent voltage surges in the circuit
d) be certain that the circuit voltage is completely interrupted
a) reduce arcing at the contacts
A rheostat is generally described as a:
a) fixed voltage divider
b) current controlling device connected in series with the load.
c) voltage controlling device
d) variable inductance
b) current controlling device connected in series with the load
Limit switches are usually used to control:
a) speed
b) torque
c) current
d) travel
d) travel
Any control device which opens a circuit on failure of voltage but does not prevent re-establishment when the voltage returns to normal operating value is known as:
a) high voltage release
b) low voltage release
c) low voltage protection
d) high voltage protection
low voltage release
A motor operating a band saw, a planer or similar equipment, which may constitute a hazard, must be controlled by a device that provides:
a) low voltage release
b) low voltage protection
c) neither a or b
d) either a or b
b) low voltage protection
Which of the following is essential in a magnetic motor starter control circuit, if then start button is momentary contact type:
a) mechanical interlock
b) holding contact
c) a low impedance solenoid
d) a time delay relay
b) holding contact
What is the difference between “2-wire control” and “3-wire control”?
two wire is for automatic operation
three wire includes manual devices such as push buttons
What is the difference between a “wiring diagram” and a “schematic diagram”
schematic is a line diagram using symbols to identify operation of circuit
Wiring is an inter. connection diagram illustrating layout of components
