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