AC/DC Drives - Chapter 10

Operational information (Output voltage, speed, etc) Diagnostic information (fault codes) Configuration options (display contrast, language, etc)

Additional things clear text displays are able to provide

Clear Text Displays

Display that has a keypad and an LCD screen that displays lines of text and numbers, and that provides more functional versatility than an LED display. Found on the majority of electric motor drives.

boost, skip frequency, S-curve, DC injection braking, and dynamic braking

Enhanced acceleration and deceleration methods include _____, ___ ______, _-_____, __ _______ _____, and _____ ______

programmable devices

Examples of these include integral keypads, keypads with clear text displays, PLC and PCs with electric motor drive programming software.

b

Increasing the ___ reduces the likelihood of an overvoltage fault and decreases the mechanical stress on the motor and driven load. A. acceleration time B. deceleration time C. minimum motor frequency D. maximum motor frequency

d

Motor ___ current is the current a motor draws, in amps, with no load when running at nameplate voltage and frequency. A. nameplate B. stator C. vector D. magnetizing

False - higher

Motors will operate more quietly at lower PWM frequencies

Range of numbers that represents selections, Bit on/off designation (1 or 0), fixed value

Parameter values that are adjustable are classified into what 3 categories

d

The ___ parameter is a parameter that prevents an electric motor drive from running a motor in reverse. A. flying start B. automatic calibration C. pwm frequency D. reverse inhibit

C

The ramp stop method of stopping a motor is a stopping method in which the ___ applied to a motor is reduced. A. Voltage B. Current C. Frequency D. Resistance

false - increasing

True/False - Decreasing acceleration time reduces the likelihood of blowing fuses or causing overcurrent faults and decreases the mechanical stress on a motor and driven load

True

True/False - If quiet operation is not necessary, lower PWM frequencies are preferred

true

True/False - The electric motor drive, motor, and load determine the acceleration and deceleration method to be used for an application

true

True/False - small basic electric motor drives can contain 50 parameters while large sophisticated drives contain over 200

True

True/false - when an acceleration time is too short, an electric motor drive draws excessive current which will blow fuses or cause over current faults.

true

True/false- applying power to a spinning motor from an electric motor drive cause a large flow of current, and the drive trips on an overcurrent fault.

frequency, speed, current, voltage, power rating, magnetizing current, and stator resistance

What data from a motor nameplate must be entered into an electric motor drive?

a

___ allows an AC motor to have torque characteristics that are almost identical to those of a DC motor A. Open loop vector control B. Quadratic Volts-Per-Hertz C. Closed Loop Vector Control D. Volts-Per-Hertz

B

___ communication is a communications port that uses a D-shell connector to connect an electric motor drive with other drives, PLCs, or PCs. A. Reference B. Serial C. Input D. Setpoint

c

___ is a control mode that provides a nonlinear voltage to frequency ratio. A. Volts-Per-Hertz B. Closed Loop Vector Control C. Quadratic Volts-per-Hertz D. Open-Loop Vector Control

C

___ parameters create the least amount of risk to equipment and personnel. A. Advanced B. Operating C. Default D. Basic

a

___ requires a braking resistor and braking controller, and cannot hold a motor shaft stationary. A. dynamic braking B. skip frequency C. DC injection braking D. smoothing

c

___ signals provide speed references to an electric motor drive from other sources, such as a potentiometer. A. digital input B. digital output C. analog input D. analog output

display mode

allows the technician to adjust electric motor drive related information that is shown on the LED or LCD display.

on the fly - aka running

certain parameters can be changed "__ ___ ___" and are identified in the electric motor drive instruction manual

keypad

common programming device for inexpensive, low horsepower drives. Normally equipped with an LED display. Best suited for simple electric motor drive applications that don't require extensive programming

serial comunication

communications port that uses a d-shell connector to connect an electric motor drive with other drives, PLCs, or PCs

interface cable

component used between the serial port or USB of a PC and the communications port on an electric motor drive to allow communication

closed-loop vector control (vector control)

control mode that allows an AC motor to have torque characteristics identical to a DC motor. Can provide 100% torque to a motor at 0 Hz speed

Volts-per-hertz

control mode that provides a linear voltage ratio to the frequency of a motor from 0 rpm to base speed. Used for constant torque loads such as conveyors

Quadratic volts-per-hertz

control mode that provides a nonlinear voltage to frequency ration. This curve matches the torque requirements of variable torque loads

open-loop vector control (sensorless control)

control mode that uses complex mathematical formulas to control the flux producing and torque producing currents to an ac motor. Mode allows an AC motor to have torque characteristics that are almost identical to those of a DC motor

Motor magnetizing current

curren a motor draws, in amps, with no load when running at nameplate voltage and frequency

motor nameplate data

data that consists of parameters related to motor specifications

DC injection braking

deceleration method that brings a motor to a smooth quick stop, and can be used to hold a motor shaft stationary for brief periods of time. Has two components: time and braking level

input mode

display mode that determines how an electric motor drive is controlled during starting and stopping

clear text display

display used to transfer sets of drive parameters between electric motor drives

basic parameters

group of parameters that are adjusted in most electric motor drive installations. Include display modes, speed references, input modes, frequency setpoints, stop modes, control modes, acceleration time, etc.

potentiometer

input control device that sends various resistance values to an electric motor drive

three wire control

input control for an electric motor drive requiring three conductors to complete a circuit

two wire control

input control for an electric motor drive requiring two conductors to complete a circuit

automatic calibration

may require an electric motor drive and motor to run with all loads disconnected, including removing sheaves from the motor shaft

Coast stop

method of stopping a motor in which the electric motor drive shuts off the voltage to a motor, allowing the motor to coast to a stop. Using this method of stopping means the drive no longer has any control of the motor after the command has been entered

ramp stop

method of stopping a motor in which the frequency applied to a motor is reduced, which decelerates the motor to a stop

default parameters

most conservative and most frequently used parameter values and create the least amount of risk to equipment and personnel

Deceleration time

motor control parameter that determines how long the length of time an electric motor drive takes to decelerate a motor from maximum motor frequency speed to a standstill.

Acceleration time (ramp up time)

motor control parameter that determines the length of time an electric motor drive takes to accelerate a motor rom a standstill to maximum motor speed.

control mode (volts per hertz pattern)

motor control parameter that determines the relationship between the voltage and the frequency an electric motor drive outputs to a motor. Allows a single electric motor drive to be used with various loads and to determine the voltage and frequency delivered to a motor

Dynamic braking

motor deceleration method that brings a motor to a smooth, quick stop. However, it requires a braking resistor and braking controller, and cannot hold a motor shaft stationary

flying start

parameter that allows an electric motor drive to lock in on the speed of a motor and ramp the motor up from that speed to setpoint. Useful when an electric motor drive is restarted after a brief power outage while the load is still spinning

automatic restart after a power outage

parameter that allows an electric motor drive to start automatically when power is once again present on the supply lines

automatic restart after a fault

parameter that allows an electric motor drive to start automatically, provided the start inputs are still closed and the fault has cleared

PWM frequency

parameter that allows the PWM frequency (carrier frequency) of a drive to be adjusted. has a range of values such as 2000 Hz to 16,000 Hz.

s-curve (smoothing)

parameter that changes the acceleration and deceleration profile from a ramp to a slope. provides sooth, nonjerky acceleration and deceleration and is used in applications where sudden starts and stops are undesirable

macro

parameter that contains predefined values for a group of parameters which are specific to a certain type of load or application such as pumps, fans, or conveyors

stop mode

parameter that determines how an electric motor drive stops when it receives a stop command. Types include ramp and coast

keypad control

parameter that disables some or all of the buttons on an electric motor drive keypad

automatic calibration

parameter that fine tunes an electric motor drive to the characteristics of a motor for optimum performance.

parameter protection

parameter that limits access to electric motor drive parameters by making them read-only unless a password is submitted.

skip frequency

parameter that prevents an electric motor drive from operating within a particular frequency range

reverse inhibit

parameter that prevents an electric motor drive from running a motor in reverse

Electric motor drive information parameter

parameter that provides information used for periodic maintenance and troubleshooting. Some of this information is permanently stored and unable to be changed, while other data is stored and updated as new events occur such as fault history and maintenance information

frequency setpoint

parameter that sets the frequency at which an electric motor drive operates when speed reference is internal. Default setting is usually a low frequency such as 5 Hz or 10 Hz.

Parameter

property of an electric motor drive that is programmed or adjusted

enhanced performance features

provide greater flexibility to make electric motor drives easier to use for technicians

start boost

provides extra torque at startup by initially applying a higher voltage

continuous boost

provides extra torque by applying a higher voltage to reach base speed, with voltage not exceeding motor nameplate voltage

digital input devices

pushbuttons, selector switches, relay contacts, and outputs of a programmable logic controller which are connected to control terminal strips. Functions include jog, start, stop, and fault reset

Motor stator resistance

resistance of the stator between any two phases

speed reference

signal that informs an electric motor drive of the speed at which to operate.

PLC

solid state control device that is programmed to automatically control an industrial process or machine

True

true/false - when deceleration time is too short, the voltage regenerated from the motor is excessive which will cause the motor drive to have a dc bus overvoltage fault

clear text displays

what display type is well suited to applications that have multiple electric motor drives of the same model, but lack a network.

potentiometer

what is an example of a component used to set external speed references using analog values?

electric motor drive instruction manuals

what should always be used by a technician when programming an electric motor drive?