SECTION 2 Test Flashcards
The longer time duration that a steady – state exists, the ________the integral action becomes.
greater
A system that oscillates is referred to as being ______
unstable
The term duty cycle refers to the amount of time a signal is ______ compared to the period of one complete cycle
on
By ______ the on – off differential gap, in the cycle time is lengthened.
increasing
The output of the derivative function [a] the output of the proportional output when the error signal is getting larger.
?
The magnitude of the integral output is proportional to the _____
all provided answers
In a PID system, after the derivative function is completed and proportional signal is ineffective the integral function is performed.
TRUE
Which section of the closed – loop system performs the four control modes?
?
List which type of operational amplifier performs the following PID mode options:
proportional
integral
derivative
?
A setpoint change can also produce offset.
T/F
TRUE
For a DC variable-speed drive to cause the motor to provide a constant horsepower to the load, it varies the motor’s____ to run it between zero RPM and a base speed, and it varies the ____ to run the motor above the base speed.
options are field strength and arm voltage
arm voltage
field strength
Referring to figure 8-7, if the motor speed slows down, the IR voltage at R11 (increase/decrease), causing the SCR’s to fire (sooner/later) in the alternation.
increase
sooner
The Armature is the primary part of the motor where an adjustable voltage is connected for speed control.
T/F
True
As the motor runs at base speed, the voltage applied to the Armature infield is_____ .
low
moderate
maximum
max
The function of Q1 in figure 8-4 is
variable resistance
To provide variable torque to a load, the DC variable-speed drive causes the speed of the motor to ___________ when an increase in torque is required.
increase
Match the application example with the appropriate motor load classification.
machine tool lathe
pump
hoist
centrifugal fan
extruder
?
Which of the following types of circuits are used by the drive controller section?
All provided answers
Regulation
Protection
AC-to-DC converter
all proided
By adjusting the DC drive so that the field current is reduced to half, the motor speed _____ .
stays the same
cut off
doubles
doubles
Which of the following motor functions can be manipulated by the operator control section?
Starting Speed Change of direction Stopping All provided answers
all
A variable-frequency drive supplies current directly to the _____.
stator
rotor
either stator or answer is both
The semiconductor switching device that is used in the inverter section of a PWM drive is the.
bipolar transistor SCR IGBT
IGBT
The __ oop of the AC closed-loop vector drive provides position information.
Outer
By using the programming capabilities of some variable speed drives, it is possible to undersize the .
All provided answers
drive
motor
either drive or all provided answer
AC drives cause the speed of an AC induction motor to change by.
changing the number of poles
varying the armature current
varying the bus voltage
varying the applied frequency
applied freq
Match the following names of the VFD sections with the appropriate circuit function that they perform
inverter
converter
intermediate circuit
converts into simulated sine wave
rectifes AC into pulsing DC
Filters pulsating
Name A method of producing the feed back signal for the following control loops in a vector drive.
Speed feedback
Current feedback
?
The auto boost circuit is used to help accelerate an AC motor when it is starting or running at a low speed.
T/F
TRUE
One common method of slowing the speed of an AC motor is to reduce the applied voltage.
T/F
False
The control function of an AC drive is used for stopping the load quickly.
braking
deceleration
speed
deceleration
Separation occurs when a mixture is
cooled
heated
both
either both or cooled
The value for a standard transmission current signal is _____ when it is zero during calibration.
4 ma
In some applications, ingredients can be mixed in a shorter amount of time by
increaseing
_____ Thermal energy is supplied to heat exchangers
both answers
Cold
Hot
both
Which of the following statements describes the control requirements that must be achieved to ensure product quality?
Quantity of raw materials Controlling the process variable during the reaction cycle All provided answers Controlling each step of the sequence
all provided
The two functions of a are to convert the output of a _______sensor into a standardized signal and to send a signal to a distant location.
transmitter
The purpose of a square root extractor is to___ .
Linearize a signal. Multiply the magnitude of a signal remove noise from the signal
multiply magnitude or
linearize a signal
A I/P transducer converts ___ to ___
current to pressure
The boiling point of a liquid can be increased if the pressure of the container in which it is heated is
All provided answers
Inverted
decreased
Increased
increased
The characteristics of a sensor refers to the time at which its output reaches a steady state after a signal is applied to the input.
static or dynamic
dynamic
