4th six mnths Flashcards
A DC meter may be compared to an electric:
Motor
In a D’Arsonval type meter, the primary purpose of the iron core is to:
Concentrate the flux between the core and the pole piece
The D’Arsonval movement operates on the principle of:
Magnetic repulsion and attraction
In most D’arsonval movements, damping is accomplished automatically without the necessity for attaching some form of air vane and container to the mechanism. This statement is:
True because oscillation of the moveable coil (or bobbin) creates induced currents in this coil which opposes the motion of the coil.
A zero adjustment screw is provided on most DC meters in order to adjust the:
Pointer to the zero setting should it be off that point
The graduations of the calibrated scale on a D’Arsonval meter are uniform. This is because the degree of armature reaction is:
Directly proportional to the current
In a DC wattmeter, the two current coils and single voltage coil are so connected that:
The voltage coil is in parallel to the line, and the current coils are in series with each other and the line.
Before using an ohmmeter, the leads should be shorted together and the variable resistance knob adjusted so that the meter reads:
Zero ohms
A shunt is connected in parallel with the coil of a DC ammeter to permit the meter to measure larger amounts of current than the meter coil could safely carry. This statement is:
True because the current being measured is caused to divide itself between the coil and the resistor.
When hairsprings are used in a D’Arsonval type meter, they:
All of the above
Current measuring instruments must always be connected in:
Series with the circuit
What two conditions may be observed in a bridge circuit?
Balance and unbalanced
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
With an ohmmeter setting on the RX1 scale. it takes .01 milliamperes to deflect the pointer to half scale. If the meter was set on the RX100 scale, how much current would it take to deflect the pointer to half scale?
.01 milliamperes
The ratings of four voltmeters are shown below. Which one would have the greatest sensitivity?
100,00 ohms per volts
The maximum current normally carried in a particular circuit is 150 amperes. The DC ammeter best adapted to this circuit from the standpoint of safe and efficient operation should have a range of:
0-300 amps
The least amount of meter error could be expected from an ohmmeter reading obtained:
From the maximum deflection area of the pointer
A meter is said to have a good deflecting torque characteristics when:
The meter responds promptly to changes in the measured force
When using a DC voltmeter:
All of the above
In the wheatsone bridge type circuit above the bridge circuit is toward point A. The resistance of Rx is :
45 ohms
In the title block displayed, what letter indicates the size of the original drawing?
A
According to the title block displayed, when was the drawing actually drafted?
11-28-90
A length of spindle shaft is specified on a drawing at 1.5 ft. Which of these actual length measurements is acceptable?
1.49ft
What kind of line does the drafting symbol displayed represent?
Centerline
In section drawings, slanted crosshatch lines represent?
Cut surfaces
Which of the six simple machines is a “continuous lever” with equal arms?
Pulley
The thread specification 10-32 NC-1B LH indicates ____ threads per inch and an ___thread.
32; internal
In the specification 10-32 NC-1B, the screw has a ___ ft and a ___ handed thread.
loose; right
According to the specifications displayed, the weld should be made on ___.
The side opposite the arrow
Sheaves are usually fitted with ____ belts.
V-shaped
On a lathe, the compound rest is the base for the ___.
Tool holder
A drawing that shows all the parts separated from one another is called a(n)?
Exploded view
On a lathe, the top and the swivel are the two main parts of a
Compound rest
What kind of drawing compresses all parts into a two-dimensional plane?
Orthographic projection
A drawing may show all the shafts of a gear train in a single plane in order to___.
Avoid confusion
In the diagram displayed, the width of the side shown is___.
15 in.
Which of the symbols displayed shows a cross-section of a supply duct?
Rectangle with X inside
The part in a duct that directs and spreads the air is called a(n);
Diffuser
The parallel development displayed is for a:
- unfolded box
Square box
What kind of development is used for making a sheet metal piece with a constant taper?
Radial line
The symbol displayed represents____
Fire brick
Most industrial plants specify bearings in terms of___. They specify distances in ___.
North; feet
The location of machinery and equip. in a building is shown in a;
Floor plan
Structural drawings of a building that can be used as a flow diagram is called a(n) ___ drawing.
Elevation
Pascal’s law states that the pressure at a hydraulic system point acts ___.
Equally in all directions
If equal pressure acts on both the rod side and the cap side of a piston, which side receives more force?
Cap side (Blank side)
Rapid pressure changes in a hydraulic system can be prevented by a(n)
Accumulator
The drawing displayed is the symbol for a hydraulic:
Reservoir
The symbol displayed represents ___lines.
Crossing
Threading is the usual method used to join ____ pipes.
Iron
Pipe threads are tapered in order to
Produce a tight joint
Flanged joints are used for joining____ pipes that carry fluids under pressure or at high temperatures.
Large-diameter industrial
Galvanic reaction is the result of joining (a)
Two different kinds of metals
A single-line piping drawing uses___ to show fittings and part sizes.
Symbols
In a wiring diagram, the symbol displayed represents a;
Fuse
The ampere is the unit of measurement for electric:
Current
The metal inside the windings of a transformer is called the
Core
A circuit diagram of a building shows the
Loads supplied by each circuit
A plot plan shows the
Distribution of electricity to all plant buildings
In an air conditioning system, the liquid that changes to a gas as it absorbs heat is called the;
Refrigerant
What part of a refrigeration system controls the flow of refrigerant from high pressure to low pressure?
Expansion vlv
In an air conditioning system, a heat exchanger is part of a(n)
Indirect A/C system
Pneumatic controls in an air conditioning system operate on
Low pressure air
A refrigerant piping drawing is usually a(n) ____ drawing.
Single-line
The main purpose of a sketch is to
Communicate an idea clearly
Objects are shown in 3 dimensions in a(n) ___ sketch.
Pictorial
In a(n) ___ sketch, parts farther from the front are drawn in the same size.
Isometric
In a(n) ___ sketch, parts that are farther away look smaller.
Perspective
Parallel lines…
Never meet
A schematic is made up of:
Symbols and lines
Double line drawings that show the internal details of a pneumatic system are called:
Cutaway drawings
In a DC circuit, the electrons flow from:
One direction only
Arrows are used in a piping diagram to indicate the:
Direction of flow
In a piping system, an alternate flow pattern is indicated by a:
Supplementary diagram
On an electrical diagram, a dashed line indicates a(n):
Exposed wire
Vent lines and drain lines are shown on a hydraulic schematic by
Dashed lines
If a schematic carries no legend, clues about it may be found in the parts list, drawing title, and
Engineer’s notes
The symbol shown below represents a:
*Circle with arrow going through
Gauge
What is the last step in troubleshooting an electrical circuit when using a schematic?
Examine the actual circuit
What electrical symbol represents connecting wires?
*A cross with dot in center
What electrical symbol represents a SPDT sw?
—-o o/ o—
What electrical symbol represents a transformer?
*Two windings with two lines between
What electrical symbol represents a fuse?
*Rectangle with two lines and connecting wires
Which electrical symbol shows NC contacts?
*A Contact with a line crossed through
An electrical circuit in which the current goes from one load to the next is called a ___ circuit.
Series
An electric circuit that allows each load to be turned on or off independently of the others is a ___ circuit.
Parallel
A wiring diagram shows how the parts of a circuit are connected:
Externally
Wires labeled “L” on a schematic:
Carry power from the source.
In the diagram shown below, the “Forward” button is marked:
FOR
The flow of material in a piping system is controlled and adjusted by:
Vlvs
Which symbol below represents a flanged joint?
—-l-l—-
Direction of flow in a piping system may be changed by a(n):
Elbow
What part of a piping system connects different diamters?
Reducer
Which symbol represents a screwed tee fitting?
*A tee with a line drawn on each leg of the tee
A vlv is used to ___ in a piping system.
Control the flow
A cock vlv is used to:
Turn flow on or off quickly
Which symbol below represents a globe vlv?
*A vlv with a colored in dot in the center
A check vlv:
Allows flow in only 1 direction
In the following symbol, the 2-in. dimension is indicated by the letter?
C
Both hydraulic and pneumatic systems:
Are fluid-power systems
In a fluid-power system, a(n) ___ reacts to the pressure of the fluid and does work.
Actuator
The symbol below represents a ___ in a ___ system.
Receiver; pneumatic
The basic symbol for a vlv shows it connections, flow paths, and:
Functions
Which symbol below represents a vlv in the closed position?
*A DCV with 4 ports (no directions)
The composit symbol shown below includes the symbol for a(n):
Electric motor
Which element of a hydraulic braking system directs the flow of brake fluid?
Valve
If the fluid in a hydraulic/ pneumatic system is used again and again it is called a(n) ___ system.
Closed
On a hydraulic/pneumatic diagram, local areas are outlined by which of the following?
Which of the symbols below represents a pushbutton?
*A square with a filled in circle in the middle
In a refrigeration subsystem of an A/C and R system, what is another term for evaporator?
Liquid chiller
What does the following symbol represent?
*A circle with a box on top
Rotary compressor
In an A/C and R system, thermostatic expansion vlvs and ADR vlvs are used in ___ control.
Direct
In a diagram for an electric control circuit, which of the following shows wiring to be installed at the site?
What solid state device in an A/C system can amplify and switch electrical signals?
Transistor
“Fusion” welding means joining two materials by ___ them together
Melting
The basic method of fusion welding that uses the “squeeze-and-heat” process is ___welding.
Resistance
Which of the following is a symbol for a weld with chamfering?
*45 degree angle
If the part is to be welded in the field, the weld symbol includes a(n)
Flag
Standard dimensions for a weld:
May appear in a legend on the welding diagram
Why do we have to measure and control?
So that we may control the quality and quantity of a product
Which of the following is an example of direct measuring?
Gauge glass
What is a mode of control?
All of the above; Proportional, floating, on and off
A device that indicates the value of the controlled variable
Measuring means
Enables the operation to bring about change in the controlled element.
Final control element
Set point:
The desired value of the controlled variable.
The term used to denote the info related to the controlled variable, is sent back to the controlling means so that corrective action can be taken is called feedback?
True
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.
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 size of a system has no affect on the process reaction rate.
False
Name 4 characteristics that affect performance of controls in an automatic control system.
*R, C, D, C
Response lag
Cycling
Dead band
Capacity
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
When force is added the vlv will close or pushing up on the vlv stem causes the vlv to close is meant by a reverse-acting vlv.
True
Vlv bodies consist of what?
*3, G, S, B
3-way vlv bodies
Gate vlv bodies
Small flow rate vlv bodies
Butterfly vlv bodies.
It is the volume of water in gallons that will flow through the wide open vlv per min. with a pressure drop of 1 psi across the vlv would best describe coefficient.
True
The term vlv trim refers to the kind of material used to make external vlv parts.
False
What qualities must a vlv stuffing box possess?
Both a and b are correct
A controlled volume pumps output is proportional to the square of its input speed.
False
What is the standard air pressure used for control purposes?
3-15psig
Electric-hydraulic is the electric signal that changes a hydraulic actuator to get the force necessary for the change.
True
Name 2 types of electrically powered devices that position final control elements?
Solenoid, electric motor operated
What are the 2 types of pneumatic piston actuators?
Proportional, On-off service
Spring loaded regulators are popular because they are simple, light in weight, and require little maintenance.
True
Large changes of the flapper in front of the nozzle cause changes through the full range of the controller is why use of a nozzle and flapper on a controller.
False
Name 2 types of air relays
Continuous bleed
Non-bleed
To achieve an increase in movement and actuate the flapper in a proportional controller, which method should be considered?
The action of measuring means
A better solution for mechanical reset for a device is to have it reset manually rather than automatically.
False
List four modes of controlling:
On-off
Proportional-plus-reset
Proportional-plus-reset-plus-rate
Proportional band
Proportion action work is achieved when it positions the vlv in proportion to change in the controlled variable.
True
Pneumatic controllers for commercial applications usually are of what capability?
Proportional-plus-reset-plus-rate
A booster relay is used to overcome response lag due to long connecting lines between the controller and vlv.
True
A basic pneumatic positioner uses what two things? Select all that apply.
Fixed orifice
Nozzle
Diaphragm pressure
Analog refers to what type of signal?
Continuous and an infinite # of points between its beginning and end values
Voltage transmitters are 4-wire transmitters.
True
On a proportional controller the desired setpoint and proportional band are usually adjusted with a potentiometer.
True
Adding time is the time it takes the controller to adjust itself back to its set point.
True
A proportional-plus-integral can be used for the control of flow, gas and liquid pressure or temperature and level applications?
True
PID control systems can be used in all systems but perform especially well in systems that have long delays.
True
What are PLC’s?
Programmable logic controllers are electronic control devices that perform many logic functions.
Communications between controllers and computers allow:
All of the above:
Data to be gathered
Control of adjustments
Operation of master-slave devices
Human Machine Interface is equipment that allows the operator to interface with the system.
True
Data transmission rate is usually expressed in:
Bauds
Name 3 types of Bourdon tubes:
C-tube
Spiral
Helical
Name the two broad types of diaphragm pressure elements:
Metallic
Non-metallic
Slack diaphragm
What is used to strengthen a metallic diaphragm unit made from two capsules?
C-spring
On pressure control devices, commonly, the high pressure side is called ___ and the low pressure side___.
Upstream; Downstream
What is a back pressure regulator?
A regulator, which controls upstream pressure by regulation the flow d/s. The controlling factor is upstream pressure, rather than d/s.
Slack diaphragm elements are used in draft gauges.
True
A manometer is a pressure gauge that responds to large pressure changes?
False
A bell-type gauge is?
All of the above:
Sensitive
Accurate
Stable
Name 3 types of mechanical pressure elements?
Bourdon springs or tubes Diaphragms Bellows liquid monomers Bell-type gauges
At what temp does all molecular activity cease?
0 degrees K
- 273 degrees R
- 460 degrees F
The 4 most common fluids to fill liquid thermometers are?
Mercury
Alcohol
Toluene
Pentane
A bimetal thermometer uses 2 strips of metal, both low coefficients of thermal expansion?
False
What are 4 usual elements used in filled-system thermometers?
*M, C, I, C
Metallic bulb containing temp sensitive fluid
Capillary tube for transmission
Indication device (Bourdon type)
Compensating elements
Name 4 disadvantages of using a filled temp system.
Changes in ambient temperature
Non linear scale
No low temp capability (mercury)
Large bulbs (gas)
What type of electronic temp sensor makes use of voltage created by joining two dissimilar metals?
Thermocouples
Thermal expansion is the principle of operation of a liquid-filled thermometer.
True
The 2 wire (current transmitter) is the most popular electronic temp transmitter.
True
Smart temp transmitters can be calibrated anywhere along the signal loop/
True
Why is a sight or gauge glass mounted on the side of a liquid tank?
To give visual indication on level of tank
How is liquid level measured by the hydrostatic method?
P= .433xGxH G= Specific Gravity
Electric liquid lvl controllers can be used for?
Low and high alarms
Discrete lvl indicators
Operate multiple outflow pumps
A popular method of liquid lvl measurement uses a differential pressure transmitter to generate a 4-20mA signal?
True
To relieve the load on a pumping system, multiple variable speed motors connected parallel may be used.
True
Liquid lvl can be determined from the weight or head pressure that a liquid exerts in a tank?
True
Dipsticks, tapes or rods are better than gauge glasses because a person must correctly check them to obtain an accurate lvl measurement?
False
Friction and changes in the specific gravity of the liquid in pilot-operated liquid lvl controllers can cause errors in the system.
True
Structural drawings of a building show its framework, floors and ___.
Foundations
The process of determining the quantity of fluid that passes a particular point in a given interval of time:
Flow measurement
Another name for differential pressure is head.
True
The most widely used orifice is:
Concentric
The equation for velocity of flow:
V= *sq root of 2gh
What type of flow meter places a blunt object in a fluid’s flow stream which creates vortices and swirls of fluid that fluctuates around the object?
Vortex flow meters
A variable-area flowmeter uses mechanisms that act against the force of fluid flow to drive a pen.
True
List three types of electronic flow meters:
Magnetic flowmeters
Vortex flowmeters
Positive displacement
A Dall Tube’s design differs significantly from the venture in two respects, name them.
An abrupt shoulder at the inlet cone comes after a short uniform section.
The low pressure tap at the throat leads to an annular groove that encircles the throat.
A popular mechanical means of measuring differential pressure is based on a mercury-filled U tube manometer.
True
The key to a turbine meter’s operation is a permanent magnet placed in a:
Coil
A magnetic flow meter restricts liquid to flow.
False
A turbine flow meter is simple, easy to install and use, and accurate to within:
99%
A choke provides fixed flow control
True
What is “K” in the formula?
Q=K*sq root of Pd
K=Flow coefficient
Why is it so important that a throttling vlv not be put in the discharge line of a positive displacement pump?
Should it close, it is possible to over pressure the line and pump.
Equipment that incorporates all the features in a single line enclosure is a?
Flow controller
Besides temp, what else is used to adjust the set point of flow controllers?
Pressure
Mechanical measuring devices installed with orifice plates use feedback mechanisms to produce a force balance.
True
The electrical analog output of the PLC is like the transmitter’s output a ___ signal.
4 to 20mA
In applications where a throttling vlv requires control, it uses 4 different systems to do this, what are they?
Measure the differential pressure
Converts it to a flow signal
Compares the signal against the desired setpoint
Produces a signal to control the vlv
A flow bean has what type of opening?
Both (Fixed and adjustable)
Electric differential-pressure transmitters are the most popular means of measuring flow.
True
In controlling gas flow, both the ___ and ___ are located in which flow is to be controlled.
Control vlv
Primary element
Name 2 types of humidity
Absolute
Relative
What is dew point?
The air temp at which water vapor begins to condense
Litmus paper when dipped into acid solution will turn ___?
Red
Name the two scales for measuring specific gravity:
API- American Petroleum Institute
Baume
Air ___ systems and ___ float systems are used to measure ___ gravity.
Bubbler
Displacer
Specific
Name 6 velocity scales:
*K S R R V F
Kinematic Specific Relative Redwood Viscosity Index Fluidity
Most PLC’s have 5 common building clocks that originated from what type of relay logic in control circuits?
Relay ladder logic
To identify the location of terminal points, modules, and modular assemblies, a method of addressing or boating these devices is needed in a digital identification system, what type of #’s locate devices?
Binary #’s
Decimal value 10= what binary #?
1010
One of the largest manufacturers of PLC in the US:
Allen Bradley
An open loop control is an automatic process.
False
A PLC requires 5 major hardware components, they are:
*P I P O P T
Power Supply Inputs Processor Outputs Programming Terminal
One of the biggest advantages of a PLC is that a technician can change the ladder logic without reconnecting the:
Input and Output devices
The processors memory section has 2 areas, they are:
Program files
Data files
Analog input modules are used in PLC systems to perform the conversion from analog signals to digital values.
True
PLC modules that interface with special sensors and devices are available for particular functions.
True
In one type of AC electrodynamometer instrument, the two field coils and the single armature coils and the single armature coil are so connected that:
All coils are in series
When a thermocouple in a thermocouple ammeter is heated it produces:
DC which is indicated on a DC meter.
When using a cross-coil power-factor meter on a 3-phase circuit, the instrument indication is accurate:
Only if the load is balanced and the power factor is the same for all phases.
A power factor meter measures the:
Ratio of true power to apparent power.
Most watt meters are a/an:
Electrodynamometer
The D’Arsonval electromagnetic movement:
Can be converted to read AC by using a bridge rectifier unit in the coil circuit.
A copper-oxide rectifier is a device that:
Is classed as a uni-directional conductor.
AC voltages in the higher ranges are usually measured with a:
Voltmeter and potential transformer.
The range of an AC ammeter may be extended by using a:
Current transformer
AC ammeters are generally calibrated to read root-mean-square valves. This also means the ammeter is calibrated to read:
Effective values
In the absence of a power-factor meter the power factor of a certain electrical load may be determined by using:
A wattmeter, a voltmeter, and an ammeter.
The junction of the two dissimilar metals of a thermocouple produces a flow of current when the junction is:
heated
Which one of the below instrument types would not utilize the effect of current to measure voltage?
Electrostatic
The meter measuring mechanism used in recording instruments is basically the same as that used for the conventional indicating instrument except in the area of:
Instrument damping setting
The circuit measuring arrangement of the most ground detector meters shows the neutral points of the ground detector potential transformer primary winding to be:
Solidly grounded
The meter whose indicated reading would be equal to E x I sin 0 is a:
Varmeter
The reliability or accuracy of power-factor meter readings would be affected the least when used on:
Single-phase circuits
The restoring torque in the concentric- scale type of frequency meter is provided for by the:
Action of the the repulsion-type movement
Each element of a polyphase watt-hour meter contains:
An induction type motor
A registering device
A retarding device
A hydraulic turbine governor must maintain a balance between the:
Water input to turbines and the power requirements on the system
Governor settings and responses must take into consideration:
All of the above
Any change in the position of the flyballs is transmitted to the pilot vlv by the:
Speeder rod
The compensating dashpot is inserted in the:
Restoring mechanism linkage
The compensating dashpot serves to prevent overtravel or hunting of the gates by re-centering the:
Pilot vlv
The rate at which the small plunger of the compensating dashpot returns to normal is usually determined by the setting of the:
Needle vlv
The adjustment provided in the speed adjusting linkage to cause the governor to add speed adjustment in the lower direction as the gates open wider is called the:
Speed droop adjustment
The governors of units designated to regulate system frequency will generally have speed droop setting closer to:
0%
An isochronous governor is one that has:
Zero speed droop
Governor safety devices usually serve to:
Any or all of the above
The principle operation of the flyball is to maintain constant speed or load on a unit.
True
At what speed does the governor allow the brakes to be applies to a generator?
From 50% to less than 50%
What is the purpose of the speed drop mechanism on an Allis-Chambers unit?
To divide the load between the generator in the desired proportions
What is the principal part of the Kaplin control mechanism?
Regulating vlv with vlv actuator and pilot vlv
What is the permanent generator designed to give?
Long service with a minimum amount of attention.
Transmission lines are used for the purpose of:
All three:
- Transmitting highest voltage
- Tying together major generating situations & primary substations
- Interconnecting major electrical systems for the interchange of power
In discussing related characteristics of transmission lines, it can be said that the higher the voltage the…
lower the I2R losses
Electrostatic and electromagnetic unbalance between phases in a 3 phase transmission line is reduced by:
Transposing or rotating the conductors
The energy stored in the magnetic fields of conductors is called:
Wattless energy
The steel core of ACSR conductors does not:
Carry any appreciable amount of load current
Suspension type insulators:
All 3:
Accept flashover
Resist thermal shock
Accept some mechanical impact
Transmission line losses due to corona may be reduced by all of the below except:
Increasing voltage value
Bundled conductors:
Reduce inductive reactance
An electrical transmission system may be caused to drop out of step or become unstable by:
All three:
Increase in load
Decrease in load
Short circuit
Switching performed under short-circuit conditions is apt to be the most disturbing to transmission lines when
Done on the low voltage side
The voltages induced in the lead sheath of underground cables may be eliminated by:
All three:
Porcelain insulators
Transposing
Cross-bonding
A material, such as thyrite, would most likely be used in:
A vlv-type lightening arrestor
All of the below are considered as advantages in the transmission of HDVC as compared to AC, except for:
The overall insulation requirements may be based on the peak rather than the actual voltages
HVDC transmission lines:
Cannot be protected from faults by using conventional circuit bkrs.
In a HVDC transmission system:
The quantity and direction of power flow be controlled with high accuracy and extreme rapidity.
An isolated system is not concerned with problems dealing with:
Interconnected system operation
Describes a control arrangement where one unit of a multi unit plant may be assigned to control frequency.
Flat frequency control
A control scheme in which each system, interconnected by the tie lines is controlling frequency simultaneously is called:
Tie-line bias control
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
The combined governor action and inertia of all generating units connected to a system is used to establish:
The frequency bias setting for that control area
Incremental loading refers mainly to:
The economical generation of electrical energy
A procedure whereby two system, not directly tied together, exchange electrical energy with each other through a third system to which they are mutually connected is called:
Wheeling energy
An intersystem tie-line meter shows high frequency and power flow out. This would be an indication of:
A loss of customer load or over-generation internally
Unit control of load and frequency is preferred over plant control because:
All of the above:
Quicker response
Component failure
Load up efficiency
Automatic control systems:
Are frequently used to control a specified sequence of operation
Manual control systems:
Are frequently used for on-off type of functions
In any system consisting of combination of manual and automatic control:
All 3:
Interlocking controls
Bypass automatic function when in manual
Protective relay precedence
Supervisory control systems differ mainly from other classes of control systems:
In the manner in which commands are transmitted and received
Double transmission is an expression relating to supervisory controls and refers mainly to:
Security
In a typical supervisory control operation:
The 1st button pushed at the master station normally sets up the circuitry needed to receive the action order to follow
The capacity of most supervisory control equipment is determined by:
The # of points provided
The reproduction at a convenient location measurements made at a remote point is called:
Telemetering
In comparing the merits of analog telemetering with those of digital telemetering it would be correct to say:
Undetectable errors can be introduced at all points in the former but only at the sending end of the latter.
A general digital information handling system would most likely include the ability to:
All three:
Solid state signals to relay action
Analog signals to digital
Read info selectively
The transfer of intelligence:
Can be accomplished either by solid wire or through space
An intraplant telephone circuit which is arranged so that either the transmitter or receiver can be switched from the circuit when not in use is called:
A push-to-talk arrangement
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
A device installed on carrier communication equipment which makes it possible for transmitter and receiver to operate continuously and without switching operations is called:
An audio hybrid unit
Carrier frequencies:
May range as high as 200KHz and as low as 30KHz
On the intermittent carrier relay system:
Transmitted signals are used to prevent relays on un-faulted sections from tripping, while relays on faulted section are tripped by no receiving signals
Carrier equipment is isolated and protected from the high voltage levels of power transmission conductors through the use of:
Coupling capacitors
A carrier relaying arrangement whereby signals are transmitted CONTINUOUSly and receivers are used to block the circuit bkr trip circuits is called:
A continuous system
A carrier drain coil would be used to:
Increase impedance at the power frequency
The line tuning unit in a carrier communication arrangement:
Provides adjustable inductance to compensate for reactance’s developed in coupling capacitors.
When a carrier circuit is coupled to a single conductor of a three-phase power line to ground as the return path, the arrangement is called a line-to-ground coupling. all of the below statements dealing with this method of coupling are true except for:
All the noise is eliminated
A method of coupling where the signal is coupled to the same phase of two circuits which provides for uninterrupted carrier is called:
Double circuit ground return coupling
Where it is desired to couple the carrier signal to several transmission lines simultaneously at a given location, the type of coupling used is:
Bus coupling
VHF & UHF radio are both used as a communication channel:
All three:
Telemetering
Relay operation
Supervisory control
Accident prevention relies on all but one of the following:
Knowledge of first-aid
An electric current passing through the body for one second or more is generally fatal if the current intensity is:
100 milliamperes
An electrical circuit should be treated as if it is energized until:
The circuit is proven de-energized
The distance at which the foot of a ladder should be placed from the wall is:
1/4 the length of the ladder to the top support
Unless protection is provided by other means, a scaffold plank should not over hang its support by more than:
18in.
For removing hazardous vapor from the air, chlorine respirator would use a:
Chemical filter
The Oxygen Breathing Apparatus will provide respiratory protection, under hard work, for a minimum period of:
45min.
The Scott Air-Pak II will provide respiratory protection for a period of approximately:
30min.
In general, the first thing you should do to help a victim of a severe accident is:
Keep the injured person lying down
A good defensive driver knows that the safe following distance to maintain while driving at speeds of 60 mph is?
120ft
Fires involving wood, textiles, paper, rubbish, and like are:
Class A
Fires involving flammable liquids such as gasoline, oils and grease are:
Class B
Dry chemical extinguishers do not have the cooling and quenching effect usually needed to quench:
Class A fires
The maximum effective range of 150lb dry chemical extinguishers is about:
25ft
The duration of discharge of a 20lb CO2 fire extinguisher is about:
45sec
The effective range of a CO2 fire extinguisher is about:
8ft
Sprinkler systems for an average office building would probably use fusible links of:
Ordinary degree
The refrigeration unit on a low pressure CO2 storage tank will maintain the temperature of the liquid at approximately:
0 degrees F
Accident prevention is attained control of:
All of the above:
Human performance
Machine performance
Physical performance
The principal hazard involving batteries is:
Acid burn
A wave trap would not be used to:
Increase impedance at the power frequency
One essential requirement to be met before two systems consider interconnecting with each other is:
That each have the capability of operating independently
The speed at which the pointer is rotating on a synchroscope is affected by:
The frequency difference between the incoming and running generator
