Automated Controls Flashcards
An washing machine is a closed loop system? True/False
False
Name the four “Basic Elements” of a closed loop system.
- Measurement Sensor
- Controller and Error Detector
- Final Control Element
- The Process
Name several alternative names for “Measurement Sensor” in a control system.
-Sensor
-Detector
-Transducer
Transmitter
Provide a few examples of open loop systems.
-Washing machine
-Toaster
-Dishwasher
They use the process of time, not measurement of outcome.
What does ISA stand for in the discipline of Automation Control?
ISA = International Society of Automation
Provide a few examples of closed loop systems?
- Water heater
- furnace with thermostat
- Natural Gas pressure regulator in the home.
What is the purpose of a P&ID Diagram?
To provide an basic schematic of the process.
What is the purpose of the block diagram?
To show the system as a set of mathematical equations that describe input to output relationship for each individual block. This allows for the evaluation of the total control system before it’s implemented.
What is negative feedback in Automated Controls?
Is measured by comparing set-point and actual result. IE like a flame in a variable furnace. As heat gets close to setpoint it reduces gas supply, then finally turns it off.
What is positive feedback in Automated Controls?
Does the opposite thing than what is desired. IE turning furnace flame higher as it gets closer to set-point. Causing runaway condition.
The “Transfer Function” of control system component primarily relates to?
The size and timing of the input to the output.
What does “Controller Action” select?
Chooses positive or negative feedback control
A device that receives info in one from and converts it to antoher form is called?
Transducer
A device that receives info in one from and converts it to another form is called?
Transducer
What is a type of transducer that includes a sensor and components to standardize and modify the sensors output?
Transmitter
What is difference between active and passive transducer?
Active gets energy from the energy output of the things it’s measuring IE Thermocouple. Passive requires power from the transducer to measure. IE Weight scale resistance sensor needs power supply to measure resistance change due to weight.
What are the two standards for measuring Voltage and current?
Current 4mA to 20mA
Voltage 1-5 Volts DC
Why use a 250 Ohm resister in control systems?
It converts 4mA to 20mA signal to 1-5 VDC signal for such devices as data loggers and alarms.
Why use current signal instead of voltage transmission?
Current has less interference over long distances without losses. It allows for a 2 wire system where power supply can be located a distance away.
Provide 2 examples of disadvantages of using current signal system.
All equipment must be connected in series.
Open loop if one thing disconnects.
What is Hysteresis in Automated Controls?
A device give an upscale or downscale error depending on which way the thing is being measured. This is usually because of slack of friction in the system.
Is a Bias Error the same as a Zero Error?
Yes. This is when Acutual output = Theoretical output
A “Span error” in a measuring device is an indication of incorrect “Gain.” True/False
True.
A “Variable Gain Error” in a measuirng device is also know as a ______ error?
Linearity