4th 6th Month Flashcards
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 tie lines is controlling frequency simultaneously is called:
tie-line bias control
A control area
is one or more systems operating with metering and control facilities on all of its ties to other systems outside of the 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 systems, 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
One essential requirement to be met before two systems consider interconnecting with each other is
that each have the capability of operating independently
Unit control of load and frequency is preferred over plant control because
it provides for quicker response during emergencies
it limits the effects of components failure
units may be loaded more efficiently
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 a combination of manual and automatic controls
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
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 ooperation
a disagreement lap will light if the wrong button is bushed
The capacity of most supervisory control equipment is determined by
the number of points provided
The reproduction at a convenient location of 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
convert solid-state signals to relay actions
convert analog signals to digital information
selectively read information which has been stored in memory
Most PLCs have five common building blocks that originated from what type of relay logic in control circuits
ladder logic
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
binary number
Decimal value 10= what binary number
1010
One of the largest manufacturers of PLC in the US
Allen-Bradley
