Moters drives unit 2, Chapter 5- motor controls and transformers, DC/AC Drives Chapter 7, 8, 9, 2 primary windings, delta, wye,
in a three phase AC generator each of the three generated voltages is how many degrees apart from each other?
120
describe possible starting methods for synchronous motors.
Dampers mounted on its rotor (induction motor), Electronic drive that gradually increases its output frequency from zero up to running speed.
In what type of generator are the three coil winding connected end to end to form a closed loop?
Delta
in what type of connection are there two phases-to-neutral legs with the same voltage and a third phase-to-neutral leg that should not be used?
Delta
Top
Each line in a line diagram should be numbered starting with the _________ line
Parallel with coil or use NO contacts
How is a lamp added into a control circuit so it is ON anytime the motor is ON?
As many as the switch and other controls amp rating allow
How many loads can be connected in parallel per line in a control circuit in which a switch is used to control the load(s)?
one
How many loads can be connected in series per line in a control circuit in which a switch is used to control the load(s)?
_________ ________allowes the motor to run at full rated torque
Armature voltage
__________ ___________ allows the motor to be ran at full load rated torque at any speed up to base speed.
Armature voltage
Name two methods of speed control typically used for a DC shunt motor,
Armature voltage control, field flux control
_______ adjustment on the DC drive used to adjust the minimum speed. limits the ________ voltage that is applied to the armature.
Min, lowest
Two methods used by DC drives to control rectified output voltage are?
SCR phase control, Pulse width modulation
series
Two loads must not be connected in _________ in one line of a line diagram.
Nand
What type of circuit logic is developed when two NC switches are connected in parallel?
Or
What type of circuit logic is developed when two NO switches are connected in parallel?
And
What type of circuit logic is developed when two NO switches are connected in series?
with ___________ __________ control the current will stay constant because it keeps the torque at full rated torque.
armature voltage
If changing the applied frequency to an AC motor changes the motor speed, how is the speed of a DC motor changed?
changing the voltage
Explain the difference between closed-loop and open-loop speed control.
closed loop speed controls receive feed back from a speed sensing device, open loop speed control do not use a speed sensor
what causes the high current that can damage the switching contacts/device?
collapse of magnetic field
What device is used to provide feedback about the position of the motor shaft to the control circuit
encoder
IR adjustment on the DC drive used to regulate the IR and give voltage a boost when additional ________ is sensed. The purpose is to improve speed regulation by compensating for the armature _________ _________.
current, voltage drop
design factors, increasing armature current will ___________ the speed.
decrease
Pulse width modulation controls the DC output voltage only after the rectifier circuit has produced ________ ____________ ___________.
peak filtered output
Explain why a synchronous motor can't be started across the line.
the magnetic field starts to rotate at synchronous speed before the router starts to turn causing torque shock
Explain why field weakening is not normally used to control the speed of a DC shunt motor operating below base speed.
the motor can run up to destructive speeds.
With ___________ __________ control the current increase because torque is reduced
field flux
what produces the stationary magnetic field of a generator?
field windings
The __________of the SCRs are triggered during each alternation of the input sine wave at a phase angle that is adjusted to control the average DC output voltage.
gates
Are slip rings used to convert generated AC voltage to DC voltage?
no
CEMF is zero when the armature is ____________ .
not turning
how dose a DC drive reverse the rotation direction of a DC motor
reverse the polarity of the voltage applied to the armature
In the rotating-field AC generator, the field winding's are mounted on the __________ part of the machine (the rotor), and the armature winding's are contained in the _____________ outer portion (the stator)
rotating, stationary
what are the two names used for the rotating part of a stepper motor?
rotor, armature
A ____________ - connected motor is typically used with DC drives.
shunt
DC voltage is controlled at the point of rectification by__________ ________ _________ in the rectifier circuit.
silicon controlled rectifiers
The difference in speed between synchronous speed and rotor speed is called _______.
slip
Max adjustment on the DC drive used to adjust the maximum _________. limits the ________ voltage that is applied to the armature.
speed, highest
voltage is regulated on a DC drive to control either motor _________or motor_________.
speed, torque
The pulse width modulation circuit uses high-speed switching transistors to produce , ___________ __________and adjusts the duty cycle to control the average DC output voltage.
square waves
The speed of the rotating magnetic field is referred to as the motor's _______ speed.
synchronous
To identify and separate the different component parts included on the individual pieces of equipment
Why are manufacturer's terminal numbers added to a control circuit?
How does adjusting the alternator's speed affect the voltage amplitudes and frequency?
voltage and frequency change proportionally.
Load
A __________ is the electrical device in a line diagram that uses the electrical power from L1 to L2.
NOT
__________ logic has an output if the control signal is OFF.
How does adjusting the field current affect the voltage amplitudes and frequency? ________________
voltage and current are directly proportional, frequency stays the same
DC drives are electronic devices that regulate the _________ or _________ supplied to DC motors.
voltage, current
Field flux speed increases when the field is ___________.
weekended
Nor
what type of circuit logic is developed when two NC switches are connected in series?
It simplifies the understanding of the function of a circuit.
why are line numbers added to a control circuit?
Explain the difference in operation between a rotating-field AC generator and a rotating-armature AC generator.
In a rotating field the brushes and slip rings carry the field current instead of the load current.
The synchronous speed of a 60 Hz, four-pole motor is _______ RPM.
1800 (Ns= 120 X 60 / 4)
in a two pole single-phase AC generator, how many mechanical degrees of rotation does the armature have to rotate to produce one completed AC sine wave?
360
A 2-pole motor is operating on a 60 Hz power supply. The rotor is turning at 3450 RPM. Slip is _______%.
4.16% (Ns=120 X 60 / 2) (% Slip = NS - NR / NS x 100)
parentheses
A numerical cross-reference system consists of numbers in _______ to the right of the line diagram.
OR
Additional start pushbuttons are connected in parallel using _______ logic with the existing start pushbuttons.
NOR
Additional stop pushbuttons are connected in series using _________ logic with the existing stop pushbuttons.
Three
All circuits are composed of _________ basic section(s).
what is another name for a DC generator?
Alternator
Digital
An example of A(n) _________ process is a standard light switch that has only two positions: fully ON or fully OFF.
Top
An integrated circuit's notch indicates the ________ of the chip.
________ _________ control reduces the torque capability of the motor.
Field flux
No additional ____________ can be developed once the field becomes saturated.
Flux
Can dynamic braking provide a controlled stop of a motor using one resistor?
No
One
No more than ________ load(s) should be placed in any circuit line between the power lines L1 and L2.
What are the effects on speed and line currents as the load on the synchronous motor increases?
Speed decreases, current increases
what are the two names used for the stationary part of the stepper motor?
Stationary field , stator
Signal
The ________ accomplishes no work by itself; it merely starts or stops the flow of current in that part of the circuit.
Simple
The dashed line method works well when the control contacts are close together and the circuit is relatively ________
ON
The load is _________ all the time if no control device is included in a line.
Complex
The numerical cross-reference method is used on _________ line diagrams.
underlined
To differenciate between NO and NC contacts, NC contacts are indicated as a number that is _________.
A DC motor, operating from zero to base speed, can be said to be operating in the constant ____________ range.
Torque
________ ________ is capable of destroying the motor if the inertia of the rotor and connected load are too great
Torque shocks
Start and Stop a motor
What function does a JOG button perform in a control circuit?
0V
When a switch is used to control a lamp or other load in a 24VAC control circuit, what is the voltage that would be measured across the switch when the switch is closed and the load is ON?
24V
When a switch is used to control a lamp or other load in a 24VAC control circuit, what is the voltage that would be measured across the switch when the switch is open and the load is OFF?
NO and Parallel
When additional switches are to be wired into a control circuit to produce additional START functions, are NO or NC contacts used and are they connected in series or parallel?
NC and series
When additional switches are to be wired into a control circuit to produce additional STOP functions, are NO or NC contacts used and are they connected in series or parallel?
Black
When connecting a DMM to L2 of a control circuit, which color DMM test lead is always used?
First use volt meter to confirm that voltage is off then use ohm meter to check resistance.
When there is a short circuit in a control circuit, what function of the meter is used to test the circuit components before the faulty component is repaired and power is restored?
To trace the action of a circuit in complex line diagrams.
Why are numerical cross-reference numbers added to a control circuit?
To keep track of the different wires that connect the components in the circuit
Why are wire reference numbers added to a control circuit?.
In what type of connection is the voltage between any one of the three phases and the neutral the same?
Wye
In what type of generator are the ends of each of the three coil winding connected together?
Wye
The two methods of connecting the armature windings of a three-phase alternator are?
Wye , Delta
circle
_______ the wire reference numbers is a common method to help differentiate wire reference numbers from other numbering systems.
Manual Automatic and Manual
________ are signal conditions
OR
________ logic is used in industry when an NO pushbutton and an NO temperature switch are connected in parallel.
Memory
_________ circuits are also known as holding or sealing circuits.
NAND
_________ logic is an extension of NOT logic in which two or more NC contacts are connected in parallel to control a load.
NOR
_________ logic is an extension of NOT logic in which two or mote NC contacts in series are used to control a load.
Why is it preferred to adjust field current rather than rotational speed to control the output voltage of an alternator?
adjusting the rotational speed also changes the frequency.
how can a DC drive provide dynamic braking
by switching a resistor across the armature when a stop button is pressed.
CL adjustment on a DC drive is used to adjust the amount of current this protects the motor from ______ due to too much current and limits output ________.
heat, torque
Describe the benefits that can be provided by permanent magnet synchronous motors.
high efficiency high power to size ratio motor control capability.
Describe the benefits that can be provided by synchronous motors with electromagnet rotors.
higher efficiency better performance at lower speeds. act as capacitors to provide adjustable power factor correction for inductive loads.
One way to increase motor speed is to ____________ armature voltage.
increase
with more mechanical load there is ________ speed.
less