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4th 6th Months > 4th 6th Month > Flashcards

4th 6th Month Flashcards

1
Q

An isolated system is not concerned with problems dealing with:

A

interconnected system operation

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2
Q

Describes a control arrangement where one unit of a multi-unit plant may be assigned to control frequency

A

Flat frequency control

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3
Q

A control scheme in which each system, interconnected by tie lines is controlling frequency simultaneously is called:

A

tie-line bias control

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4
Q

A control area

A

is one or more systems operating with metering and control facilities on all of its ties to other systems outside of the control area.

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5
Q

The combined governor action and inertia of all generating units connected to a system is used to establish:

A

the frequency bias setting for that control area.

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6
Q

Incremental loading refers mainly to

A

the economical generation of electrical energy

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7
Q

A procedure whereby two systems, not directly tied together, exchange electrical energy with each other through a third system to which they are mutually connected is called

A

wheeling energy

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8
Q

An intersystem tie-line meter shows high frequency and power flow out. this would be an indication of:

A

a loss of customer load or over-generation internally

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9
Q

One essential requirement to be met before two systems consider interconnecting with each other is

A

that each have the capability of operating independently

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10
Q

Unit control of load and frequency is preferred over plant control because

A

it provides for quicker response during emergencies

it limits the effects of components failure

units may be loaded more efficiently

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11
Q

Automatic control systems

A

are frequently used to control a specified sequence of operation

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12
Q

Manual control systems

A

are frequently used for on=off type of functions

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13
Q

in any system consisting of a combination of manual and automatic controls

A

means are generally provided for interlocking the various controls

the automatic functions may be bypassed when the switch is turned to manual

protective real operation will take precedence over other types of operations

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14
Q

Supervisory control systems differ mainly from other classes of control systems

A

in the manner in which commands are transmitted and received

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15
Q

Double transmission is an expression relating to supervisory controls and refers mainly to

A

security

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16
Q

In a typical supervisory control ooperation

A

a disagreement lap will light if the wrong button is bushed

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17
Q

The capacity of most supervisory control equipment is determined by

A

the number of points provided

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18
Q

The reproduction at a convenient location of measurements made at a remote point is called

A

telemetering

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19
Q

In comparing the merits of analog telemetering with those of digital telemetering it would be correct to say

A

undetectable errors can be introduced at all points in the former but only at the sending end of the latter

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20
Q

A general digital information handling system would most likely include the ability to

A

convert solid-state signals to relay actions

convert analog signals to digital information

selectively read information which has been stored in memory

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21
Q

Most PLCs have five common building blocks that originated from what type of relay logic in control circuits

A

ladder logic

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22
Q

To indentify 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 numbers locate devices

A

binary number

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23
Q

Decimal value 10= what binary number

A

1010

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24
Q

One of the largest manufacturers of PLC in the US

A

Allen-Bradley

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25
Q

One of the biggest advantages of a PLC is that a technician can change the ladder logic without reconnecting the

A

input and output

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26
Q

The processor’s memory section has two areas, they are

A

program files

data files

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27
Q

Analog input modules are used in PLC systems to perform the conversion from analog signals to digital valures

A

true

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28
Q

PLC modules that interface with special sensors and devices are available for particular functions

A

true

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29
Q

Spring-loaded regulators are popular because they are simple, light in weight, and require little maintenance? t/f

A

True

30
Q

Why use a nozzle and flapper on a controller

A

A small force is required to position that flapper and produce a full range of pressure valves for control

31
Q

name two types of air relays

A

continuous bleed

hon bleed

32
Q

To achieve an increase in movement and actuate the flapper in a proportional controller, which method should be considered?

A

the action of the measuring means

33
Q

A better solution for mechanical reset for a device is to have it reset manually rather than automatically. t/f

A

false

34
Q

list the four modes of controlling

A

on-off ( two-position)
proportional band
proportional plug rest
proportional plug reset plus rate

35
Q

how does proportional action work

A

it positions the valve in proportion to change the controlled variable

36
Q

Pneumatic controllers for commercial applications usually are of what capability

A

proportional plus rest plus rate capability

37
Q

what is used to overcome response lag due to long connecting lines between the controller and valve?

A

a booster relay installed at the valve location overcomes most of the response lag created by the long connecting lines and insufficient output volume

38
Q

A basic pneumatic position-er uses what two things

A

fixed orifice and nozzle

diaphragm pressure

39
Q

Analog refers to what type of signal

A

continuous and has an infinite number of points between its beginning and ending valves.

40
Q

Voltage transmitters are 4-wire transmitters t/f

A

true

41
Q

on a proportional controller the desired set point and proportional band are usually adjusted with a potentiometer t/f

A

true

42
Q

adding time is the time it takes the controller to adjust itself back to its set point t/f

A

false

43
Q

A proportional plus integral controller can be used for the control of flow, gas and liquid pressure or temperature and level applications t/f

A

true

44
Q

PID control systems can be used in all systems but perform especially well in systems that have long delays t/f

A

true

45
Q

what are PLC’s

A

programmable logic controllers electronic control devices that perform many logic functions

46
Q

communications between controllers and computers allow:

A

data to be gathered
the control of adjustments
the operation of master-slave devices

47
Q

human machine interface is equipment that allows the operator to interface with the system t/f

A

true

48
Q

Data transmission rate is usually expressed in

A

bauds

49
Q

Name the three types of bourdon tubes

A

simple c-tubes
spiral
helical

50
Q

name the two broad types of diaphragm pressure elements

A

metallic

nonmetallic

51
Q

what is used to strengthen a metallic diaphragm unit made from two capsules

A

a c-spring

52
Q

on pressure control devices, commonly, the high pressure side is called _____ and the low pressure side _____

A

upstream

downstream

53
Q

what is a back pressure regulatot

A

regulating the rate at which find flows downstream controls upstream pressure. the control of upstream pressure is commonly called back pressure control

54
Q

slack diaphragm elements are used in draft gauges t/f

A

true

55
Q

a manometer is a pressure gauge that responds to large pressure changes t/f

A

false

56
Q

a bell-type gauge is

A

sensitive
accurate
stable

57
Q

Name 3 types of mechanical pressure elements

A

four-wire voltage transmitter
two-wire current transmitter
smart transmitter

58
Q

why is a sight or gauge glass mounted on the side of a liquid tank

A

it gives visual indication of the level and can be view continuously

59
Q

How is liquid level measured by the hydrostatic method

A

for each foot of vertical height a column of water produces a pressure of approx. .433psi. use the formula p=.433gh
g= specific gravity
h= height above the metering ground

60
Q

A popular method of liquid level measurement uses a differential pressure transmitter to generate a 4-20mA signal? t/f

A

true

61
Q

To relieve the load on a pumping system, multiple variable speed motors connected parallel may be used. t/f

A

true

62
Q

What is flow measurement

A

The process of determining the quantity of fluid that passes a particular point in a given interval of time.

63
Q

Another name for differential pressure is head. t/f

A

true

64
Q

The most widely used orifice is

A

concentric

65
Q

the equation for velocity of flow

A

v= square root 2gh

66
Q

a variable-area flowmeter uses mechanisms that act against the force of fluid flow to drive a pen. t/f

A

true

67
Q

list three type of electonic flow meters

A

magnetic flow meter
mass flow meter
vortex flow meter

68
Q

a dall tubes design differs significantly from the venturi in two respects name them

A

an abrubt shoulder at the inlet cone comes after a short uniform section

the low pressure tap at the throat leads to an annular grove that encircles the throat.

69
Q

A popular mechanical means of measuring differential pressure is based on a mercury-filled u tube manometer t/f

A

true

70
Q

The key to a turbine meters operation is a permanent magnet placed in a

A

coil

71
Q

a magnetic flow meter restricts liquid to flow t/f

A

false

72
Q

a turbine flow meter is simple, easy to install and use, and accurate to within

A

99%

4th 6th Months (2 decks)

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