Motor Control 3 Flashcards
What are the 3 types of DC motors?
- ) Series
- ) Shunt
- ) Compound
How many SETS of contacts do DC motors utilize?
1 Set (2 Contacts)
Rheostats are ____ control devices, meaning a person has to be there to operate it.
Manual
How do Rheostats change motor speed?
By changing the amount of current to the armature. (To which it is usually wired in series)
____ are a safety feature for maintaining connection after motor speed has reached maximum.
Holding Coils
T/F: Contactor starting connects partial voltage when first connected.
False, full voltage is connected across the contacts.
____ are segments that cool and separate arcs. Usually 80% of the energy is absorbed.
Arc Chutes
A ____ creates a magnetic field that extinguishes the arcs.
Blowout Coil
What are 3 ways that drives are better than rheostats>
- ) No human required to operate
- ) Less power to operate
- ) Cheaper in the long run
Motor speed monitoring is done with what 2 devices?
- ) Tachometer
2. ) Encoder
How do you reduce the speed of a DC motor?
Reduce Armature voltage
How do you increase the speed of a DC motor?
Reduce field winding voltage
What are the two parts of a DC drive?
- ) Power section
2. ) Control section
How does the control section of a DC drive control motor speed?
By quickly switching to dictate how much of the power is delivered to the motor, and when.
___-loop control has motor characteristics pre-programmed into the controller.
Open-loop, which is cheaper.
____-loop control uses sensors to monitor motor characteristics, adjusting as needed.
Closed-loop
What are the two types of DC motor braking?
Except for Friction Braking
- ) Dynamic - Braking Resistors
2. ) Regenerative - Back to power source
What is the most common analog range?
4-20mA
What are the two reasons that using 4-20mA is the most common analog range?
- ) Longer range (Current, no voltage drop)
2. ) Less to no issues from electrical noise.
What are the three types of analog signals?
- ) Current (4-20mA)
- ) Voltage (0-5vDC, 1-5vDC)
- ) Pressure (3-15PSI)
A ____ converts a signal to one that is more usable by the device.
Signal Conditioner
Limit Alarms are also known as ____.
Level-Relays
How can you use a 1-5vDC device with a 4-20mA system ?
With a 250 Ohm Resistor.
A ____ converts one type of energy to another, usually for reading/signal purposes.
Transducer
What are the two parts of a transducer?
- ) Sensor
2. ) Transmitter
What are the two types of temperature sensors that vary resistance with temperature?
- ) RTD
2. ) Thermistor
What are the 2 types of temperature sensors that produce a small voltage when heated?
- ) Thermocouples
2. ) Solid State Temperature Sensors
Wires coming off of a thermocouple must be as short as possible to mitigate voltage drop, so they are usually ran to a nearby ____.
Reference block.
What are the 3 Position Sensing devices?
- ) Linear Potentiometers
- ) Rotary Potentiometers
- ) LVDT (Movable Core)
What are the 6 Pressure Sensor types mentioned in the book?
- ) Deflection
- ) Differential
- ) Bourden Tube
- ) Piezoelectric
- ) Direct (Strain Gauge + Load Cell)
- ) Solid State
What are the 6 types of Flow sensors that the book mentions?
- ) Paddle Wheel
- ) Turbine
- ) Vortex
- ) Electromagnetic
- ) Ultrasonic
- ) Mass (Thermal + Coriolis)
A Vortex-type flow sensor contains a component called the ____ which contacts the liquid to create vortices, which are utilized for measuring flow.
Bluff-Body
Ultrasonic-type flow sensors utilize ____ in the fluid they are reading, for receiving sound waves back.
Particulates
Current Sinking, NPN or PNP?, switch on the positive or negative side?
Sinking = NPN = switches on the Negative side.
Current Sourcing, NPN or PNP?, switch on the positive or negative side?
Sourcing = PNP = switches on the positive side.
How is an AC/DC input module able to utilize AC power?
Because it has Reverse parallel diodes.
T/F: TTL input modules are heavy duty.
True
What are the 4 types of input modules?
- ) Current Sinking
- ) Current Sourcing
- ) AC/DC
- ) TTL
What are the 3 types of output modules?
- ) DC Output (Current sinking)
- ) AC Output (Uses Triacs)
- ) TTL