MISC Flashcards
A carrier drain coil would be used to:
Increase impedance at the power frequency
A term derived from the fact the control action produced by the feature is based on the rate at which the controlled variable changes value.
Rate Response
A vlv is used to ___ in a piping system.
Control the flow
Analog refers to what type of signal?
Continuous and an infinite # of points between its beginning and end values
At what temp does all molecular activity cease?
0 degrees K
-273 degrees R
-460 degrees F
Besides temp, what else is used to adjust the set point of flow controllers?
Pressure
Describes a control arrangement where one unit of a multi-unit plant may be assigned to control frequency
Flat frequency control
direct current is electric current that flows
one direction
dry chemical extinguishers consist of a powder composed of
highly refined soda
Electric liquid level controllers can be used for?
Low and high alarms
Discrete level indicators
Operate multiple outflow pumps
Final control element
Enables the operation to bring about change in the controlled element.
for an oxygen breathing apparatus complete respiratory protection is provided for a minimum of
45 minutes
for co2 extinguishers the approx. duration of discharge is
20lbs 45 sec
how does proportional action work
it positions the valve in proportion to change the controlled variable
How is liquid level measured by the hydrostatic method?
for each foot of vertical height a column of water produces a pressure of approx. .433psi. use the formula: P= .433xGxH
G= Specific Gravity
h= height above the metering ground
how is ohm meter different from and ammeter and volt meter
it has its own power and axillary control circuit
In first using a multirange DC voltmeter on a circuit of UNKNOWN voltage, set the range selector at:
The highest point and work downward until the proper range is determined
Is a radio frequency signal modulated by another signal modulated by another signal at an audio frequency rate, and thus carries the intelligence of the second signal.
Carrier current
Monometer is a pressure gauge that responds to large pressure changes
b) false
Most PLC’s have 5 common building clocks that originated from what type of relay logic in control circuits?
Relay ladder logic
Name 2 types of air relays
Continuous bleed
Non-bleed
Name 2 types of electrically powered devices that position final control elements?
Solenoid, electric motor operated
Name 3 types of mechanical pressure elements
four-wire voltage transmitter
two-wire current transmitter
smart transmitter
Name the two scales for measuring specific gravity:
API- American Petroleum Institute
Baume
One or more systems operating with metering and control facilities on all of its ties to other systems outside of the control area.
Control area
out of the four characteristics which one does not affect the performance of the controlled in the automatic controlled system?
distance
Pneumatic controllers for commercial applications usually are of what capability
proportional plus rest plus rate capability
power factor measures
the watts over volts ampers
Set point:
The desired value of the controlled variable.
Structural drawings of a building that can be used as a flow diagram is called a(n) ___ drawing.
Elevation
The 2 wire (current transmitter) is the most popular electronic temp transmitter.
TRUE
The 4 most common fluids to fill liquid thermometers are?
Mercury
Alcohol
Toluene
Pentane
the compensating dashpot serves to prevent over-travel or hunting of the gates by
re-centering the pilot valve
The composite symbol shown below includes the symbol for a(n):
Electric motor
the control area =
one or more systems operating with metering and control facilities on all its ties to other systems outside the control area
the electrical analog output of the tlc is like the transmitters output
2 to 20 milliamp signal
The movement the primary element must move before the controlled element starts to move. Where no output action occurs
Dead zone or dead band
The process of determining the quantity of fluid that passes a particular point in a given interval of time:
Flow measurement
the process where two systems not directly tied together may exchange electrically energy with each other through a third system to which they are mutually connected
wheel energy
The processors memory section has 2 areas, they are:
Program files
Data files
the speed in which the syncroscope indicator is rotating is affected by
Look up
The steel core of ACSR conductors does not:
Carry any appreciable amount of load current
The symbol below represents a ___ in a ___ system.
Receiver; pneumatic
thyrite would most likely be used with
valve type lightning arresters
What are PLC’s?
Programmable logic controllers are electronic control devices that perform many logic functions.
what are two types of electrical power devices that position final control elements
solenoid and electric motor
what controls and maintains the wicket gates as it opens to allow the generator to get up to main speed
gate limit device
what controls the amount of water flowing past the point during an interval of time
rate of control
What is a back pressure regulator?
Regulating the rate at which find flows downstream controls upstream pressure. The control of upstream pressure is commonly called back pressure control
What is lag and what is it caused by?
Time lapse that occurs between the moment a set point change command is sent and when it occurs, caused by primary elements, measuring means, sensors or other items in the system.
what is not a usual element filled temperature system
bi metal strip
what is not an advantage of hvdc transmission lines
overall insolation requirement may be based on the peak rather than actual voltage
what is not Boolean algebra
notit
What is used to strengthen a metallic diaphragm unit made from two capsules?
C-spring
what powers the flay ball
pmg - permeant magnet generator
when using an ohm meter short the leads together and set the meter to read ___ while adjusting the zero adjustment knob.
zero ohms
Which of the symbols below represents a pushbutton?
*A square with a filled in circle in the middle
which three is a mode of controlling
on/off
proportional plus reset,
proportional plus reset plus rate
Why do we have to measure and control?
So that we may control the quality and quantity of a product
Why use a nozzle and flapper on a controller
A small force is required to position that flapper and produce a full range of pressure valves for control
