All project related information is stored in a separate folder created for each project. The
folder is created automatically when you start a new project in PTW. All the one-line
diagrams, report files and project data files for each project are stored in the project folder.
Database
One of the most important concepts in PTW is that the database stores all of the project
information. An individual component may be displayed on any number of one-line
diagrams and TCC drawings, but it is a single entity in the database. You can add
components to the project database from a TCC drawing, a one-line diagram or the
Component Editor.
One-Lines TCCs
Component Editor Motor Starting
Harmonics Stability
Project
Database
We recommend adding components to a one-line diagram and referencing them on TCC
drawings. The one-line diagrams provide a convenient way to describe the power system
topology and component connections. The actual component names, connections, and data
are stored in the database and only referenced on the one-line diagrams and TCC drawings.
Deleting a component from the database will automatically remove it from all of the oneline
diagrams and TCC drawings where it was displayed.
Multiple One-line Diagrams
Since the database stores the entire project and system model information, all or any
selected part of the system model can be displayed on any number of different one-line
diagrams. This allows you to have an over-all system one-line as well as smaller one-lines
that display specific sub-stations, areas, processes, buildings, etc. Groups of components
can be copied from one one-line diagram and copied to other one-line diagrams. You can
also selectively hide and display project components on any of the one-line diagrams. If
you understand that the one-lines and TCC drawings simply display components and their
connections from the project database, you can understand how a component or group of
components can be displayed on multiple one-lines in the same project.
Connecting Components on the One-line
It is important to note that system studies require definition of impedance between
designated points in the power system. Traditionally, these designated points are called
“Buses” and the impedance components connecting the buses are called “Branches”.
Traditionally, each end of an impedance component must be connected to a bus.
Components that don’t have defined impedance or the negligible impedance is ignored
(such as relays, breakers, switches, etc.) can be connected in series with impedance devices
without affecting the impedance connections. A few examples will help illustrate the
allowable connections in PTW:
- You cannot place two impedance components in series without an interconnecting bus or
bus-node. (When we refer to impedance components, we mean cables, 2-winding and 3-
winding transformers, transmission lines, pi impedances, motors, generators and loads.)
If you connect two impedance components in series, PTW will automatically insert a bus
or bus-node.
Invalid Valid
Bus
Bus
Bus
Impedance
Impedance
Impedance
Impedance
7
SKM Power*Tools for Windows
- In order to connect any two buses, you must use at least one impedance device. This
means that you cannot connect two buses with only a protective device (such as a fuse or
circuit breaker). Once you have an impedance device in the connection, though, you may
insert multiple protective devices into the connection.
Invalid Valid Valid
- To simulate a tie breaker, you must use an impedance device such as a cable or a pi
equivalent impedance component. The pi equivalent usually works best:
Pi impedance
Impedance
(Cable)
No
Impedance
(Relay)
No
Impedance
(Relay)
Impedance
(Cable)
No
Impedance
(Breaker
and Relay)
Navigation between Windows and Documents
PTW is made up of several different Document types including One-line diagrams, Reports,
Time-Current-Coordination (TCC) drawings, Data Visualizer, and the Component Editor.
It is important to know how to navigate between the different Windows and Documents that
may be open. Each Document Type has a separate icon and can also be accessed from the
Document menu. The document icons follow:
The icons represent in order:
Component Editor; One-lines; TCC Drawings; Reports; Data Visualizer; and Libraries.
If you want to navigate to a different document that is already open, use the Window menu
to display a list of open documents. If you become out-of-step with the tutorial, use these
options to navigate back to the correct document.
The Window Menu lists the documents that are presently open and has a check mark next
to the document that is in focus (on top). The menu options in PTW will vary depending on
which type of document is in focus. It is important to know how to switch between open
documents in PTW to use the program efficiently.