motor controls test 2
a voltage-output pressure typically outputs 0 vdc to __ vdc proportional to the rating of the pressure sensor
10
a current-output pressure sensor typically outputs 4 ma to __ ma proptional to the rating of the pressure sensor
20
__ is one of the most suitable industrial applications of SCRS
DC motor control
with a __ thermistor, an increase in temperature causes the resistance of the thermistor to decrease
NTC
electrically, a diac operates in a manner similar to two __ that are connected in series in opposite directions
Zener diodes
an op amp is often used in digital circuits that require the __ amplification of a weak signal
analog
hall voltage varies depending on how close the magnet is to the hall generator, which acts as a __ signal
analog
the n-type material is a unijunction transistor functions as the __ and has two leads
base
in a two-lead phototransistor, the __ is replaced by a clear covering that allows light to fall on the base region
base lead
in any transistor circuit, the __ junction must always be forwarded biased
base/emitter
__ torque is the maximum torque a motor can provide without an abrupt reduction in motor speed
breakdown
a gate current is used to reduce the level of __ voltage necessary for an SCR to conduct or fire
breakover
the __ layer is present to prevent th edepletion region extending into the bipolar collector when using an IGBT for blocking
buffer
__ sensors can detect materials such as plastic, glass, water, moist wood
capacitive
amplifiers connected together are called __ amplifiers
cascaded
the __ is the first layer of protection for the glass or plastic core of an optical fiber cable
cladding
in __ circuit transition, a motor remains connected tot he voltage source when switching from a reduced starting voltage level to a running voltage level before reaching full motor speed
closed
speed and torque are inversely proportional in __ loads
constant gorsepower/variable torque
an example of a __ load is a center-driven winder used to roll and unroll materials such as paper or metal
constant/horsepower variabletorque
__ current flow is the movement of electrons from positive to negative
conventional
the __ flowing through a photodiode increase as the resisitance decreases
current
the __ region is the point at which the transsitor is turned off and no current flows
cutoff
a __ operated photoelectric control that energizes the output switch when a target is present(breaking the beam)
dark
__ mode is the operation of a MOSFET with a negative gate voltage
depletion
as electrons move across the __ of a light-emitting diode, they give up extra kinetic energy, which is converted to light
depletion region
an optocoupler uses a glass __ sandwich to separate input from output
dielectric
the __ provides wide bandwidth and high impedance ina an op amp
differential amplifier
when transistors are used as switches, a __ can be mounted across the transistor prevent damage from high-voltage spikes (transients)
diode
__ mode is a method of ultrasonic sensor operation in which the emitter and receiver are placed opposite each other so that the sounmd waves from the emitter are received directly by the receiver
direct
the best scanning method for heightand distance monitoring is __ scan with modulated controls
direct
the __ light beam is the area of light that travels directly from the transmitter to the receiver
effective
communication is the transmission fo information from one point to another by means of __ waves
electromagnetic
a proximity sensor is a solid state sensor that detects the presence of an object by means of a __ sensing field
electronic
since a __ MOSFET does not conduct at zero gate voltage, it is often called a normally off MOSFET
enhancement
the main body of a __ mosfet is composed of a highly resistive P-type material
enhancement
a voltage __ is an increase or decrease in the normal line voltage within the range of +5 to ~/10%
fluctuation
starting torque si the torque required to start a mtoro and s normally expressed as a percentage of __ torque
full-load
__ starting is the least expensive and most efficient means of starting a motor for applications involving small-horsepower motors
full-voltage
__ is a ration of the amplitude of an output signal to the amplitude of an input signal
gain
a __ serves as the control point for an SCR
gate
the two sections of P-type material constitute the __ of a JFET
gate
for optimum performance, the photoelectric source should be operated when its LED is __
green
__ actuation is an active method of hall effect sensor activation in which a magent is oriented perpendicular to the surgace of the sensor an dis usually centered over the point of maximum sensitivity
head-on
problems with IGBT and other solid-state switches can be reduced by keeping their __ clean for proper airflow movement
heat sinks
triacs cannot replace SCRs in __ applications
high-current
Jfets are used extensively I ncircuits where low power and high __ are factors
impedance
a __ transient voltage is a transient voltage commonly caused by lightning strikes and when loads with coils are turned off
impulse
__ heated thermistors are used for precision temperature measurement and temperature compensation
indirectly
a __ proximity sensor is a sensor that detects only conductive substances
inductive
the main difference in construction between the power MOSFET and IGBT is the addition of a __ layer in the IGBT
injection
when any motor is started, high __ current is produced
inrush
the "pin" in pin photodiode stands for P-type material, __, and n-type material
insulator
reduced voltage starting provides __ current draw over a longer period of time than full-voltage starting
invremental
the __ resisitance measurements taken when troubleshooting IGBT are used to determine whether the resisitance is too low and the device is defective
leakage
the primary difference between a photodiode and a regular diode is that a photodiode has an addition of a __ in its housing for focusing light on the PN junstion
lens
a photoconductive cell is a device that conducts current when energized by __
light
hall effect sensors are also used to replace mechanical __ switches in application sthat require the detection of an objects position
limit
motors that are started at reduced boltage must be switched to __ voltage before reaching full speed
line
__ current is th eamohnt of current drawn by a load when energized
load
__ torque is the torque a motor produces whenits rotor is stationary and full power is applied to the motor
locked rotor
in an __ light source, the light source is turned on and off at a very high frequency, normally several kilohertz
modulated
a __ power interruption is a decrease to 0 v on one or more power lines lasting from .5 cycles up to 3 sec
momentary
because there is a small delay before a flow detection sensor heats enough hto signal no flow, the sensor acts like a __, which allows for a short time delay to pass before signaling a problem
motor starter overlaod
a diac has __ resistance because it does not conduct current until the voltage across it reaches breakover voltage
negative
__ error is a slight mismatch between internal components
offset
a __ transient voltage is a transient voltage commonly caused by turning off high inductive loads and by switching off large utility power factor correction capacitors
oscillatory
A __ is needed to properly test and SCR under operating conditions
oscilloscope
in darkness, a phototriac is not triggered. the remaining leakage current is referred to as __ current
peak blocking
a transient voltage measurement is different from a standard voltage measurement becaue a standard measurement displays the rms voltage value of a circuit and a transient voltage measurement dispays the __ value of a circuit
peak voltage
__ control is the control fo the time relationship between two events when dealing with voltage and current
phase
a fiber optic receiver normally contains a __ that converts light back into electrical signals
photodiode
one disadvantage of an IGBT is that the switchting speed is inferior to the of a __ MOSFET
power
__ torque is also referred to as accelerating torque
pullup
the larger the horsepower size of a dc motor, the less the __ and the higher the current
resistance
a photocell is, in effect, a variable __
resistor
__ scan is a method of scanning in which the transmitter and receiver are housed in the same enclosure and the transmitted light beam is reflected back tot he receiver from a reflector
retroflective
as long as the emitter voltage remains less than the internal voltage, the emitter junction will remain __ even at a very high voltage
reverse biased
an important feature of triacs if the absence of a __ condition of high voltages and high current, such as those found in diodes and SCRs
reverse breakdown
triacs are the equivalent of two SCRS connected in a __ arrangement with gates also connected to each other
reverse-parallel
materials such as foam, fabric and __ are difficult for ultrasonic sensors to detect and are better detected by photoelectric or proximity sensors
rubber
voltage___ commonly occur when high current loads such as motors areturned on
sags
an induction motor acts much like a __ in the secondary of a transformer when it is started
short circuit
a flow detection sensor is a sensor that detects the movements of liquid or gas using a __
solid-state devie
__ scan distinguishes between shiny and nonshiny surfaces
specular
motors draw large amounts of current when running and even more current when __
starting
triacs, diacs, UJTS, SCRS operate only as __
switches
Power MOSFET were designed primarily for __ applications
switching
a __ is a connection brought out of a winding at a point between its end oints to allow the voltage or current ratio to be changed
tap
a thermistor is a __ sensitive resistor
temperature
a flow detection sensor operates on the principle of __ conductivity
thermal
since all motors produce __ that can be used to operate loads, all motors are capable of producing work
torque
the type of load and operating torque requirements of an application must be understood because the type of load and any changes in required operating __ are programmed into ta drive before the system is operated and when any load requirement changes are made
torque
photoelectric sensors that switch DC circuits normally use __ as the switching element
transitors
A UJT is typically used as a triggering circuit for a __or similar device
triac
diacs are used almost exlusively as __ devices
triggering
a JFET is a __ device
unipolar
with __ loads, a motor must work harder to deliver more output at a faster speed
variable torque/bariable horsepower
examples of __ loads include fans, blowers, centrifugal pumps, mixers and agitators
variable torque/variable horsepower
the main difference in operation between a JFET and MOSFET is that __ is applied between the gate and the P and N regions of the MOSFET structure
voltage
a __ is a noninverting amplifier
voltage follower
