SCADA As Heart Of Distribution Management System

April 23, 2013

SCADA – The Heart Of Distribution Management System (DMS) – On photo: Fima UAB – Dedicated control systems and SCADA (Supervisory Control and Data Acquisition) as well as DMS (Distribution Management System) type of systems are offered for electricity, water and gas supply companies, as well as telecommunication operators and manufacturing companies.

SCADA System Elements

At a high level, the elements of a distribution automation system can be divided into three main areas:

  1. SCADA application and server(s)
  2. DMS applications and server(s)
  3. Trouble management applications and server(s)

Distribution SCADA

As was stated in the title, the Supervisory Control And Data Acquisition (SCADA) system is the heart of Distribution Management System (DMS) architecture.

A SCADA system should have all of the infrastructure elements to support the multifaceted nature of distribution automation and the higher level applications of a DMS. A Distribution SCADA system’s primary function is in support of distribution operations telemetry, alarming, event recording, and remote control of field equipment.

“Historically, SCADA systems have been notorious for their lack of support for the import, and more importantly, the export of power system data values.”

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Responding to Cyber Intrusion in SCADA System

April 23, 2013

responding-cyber-intrusion-scada-systemContinued from technical article: Detecting Cyber Intrusion in SCADA System

The Three R’s As Response

The “three R’s” of the response to cyber intrusion are:

  1. Recording,
  2. Reporting, and
  3. Restoring.

Theoretically, it would be desirable to record all data communications into and out of all substation devices.

In that manner, if an intruder successfully attacks the system, the recordings could be used to determine what technique the intruder used, in order to modify the system and close that particular vulnerability. Secondly, the recording would be invaluable in trying to identify the intruder.

In addition, if the recording is made in a way that is demonstrably inalterable, then it may be admissible as evidence in court if the intruder is apprehended.

However, due to the high frequency of SCADA communications, the low cost of substation communications equipment, and the fact that the substations are distant from corporate security staff, it may be impractical to record all communications.

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Detecting Cyber Intrusion in SCADA System

April 23, 2013


How to recognize intrusion?

One of the axioms of cyber security is that although it is extremely important to try to prevent intrusions into one’s systems and databases, it is essential that intrusions be detected if they do occur.

An intruder who gains control of a substation computer can modify the computer code or insert a new program. The new software can be programmed to quietly gather data (possibly including the log-on passwords of legitimate users) and send the data to the intruder at a later time.

It can be programmed to operate power system devices at some future time or upon the recognition of a future event. It can set up a mechanism (sometimes called a ‘‘backdoor’’) that will allow the intruder to easily gain access at a future time.

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How to determine motor torque & speed requirements

April 23, 2013


Operating Speed Range

The desired speed range may be difficult to achieve depending on the type of application. In general, depending on motor size and load type, very wide ranges may require a special motor.

Operation at very low speeds, requiring the motor to run at very low frequency (below approximately 6 Hz) or very high speeds requiring the motor to run at very high frequencies (above 90 Hz) may require a special motor.

Motor synchronous speed varies directly with the control output frequency. Therefore, the frequency required to achieve a desired application speed can be approximated by dividing the desired speed by the motor rated speed and then multiplying by the rated frequency of the motor.

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Torque Of Three-Phase Induction Motor Explained

April 23, 2013


Introduction to torque

The rotating force that a motor develops is called torque.

Due to the physical laws of inertia, where a body at rest tends to remain at rest, the amount of torque necessary to start a load (starting torque) is always much greater than the amount of torque required to maintain rotation of the load after it has achieved normal speed.

The more quickly a load must accelerate from rest to normal rotational speed, the greater must be the torque capability of the motor driver.

“For very large inertia loads or loads that must be accelerated quickly, a motor having a high starting torque should be applied.”

The National Electrical Manufacturers Association (NEMA) provides design letters to indicate the torque, slip, and starting characteristics of three-phase induction motors.

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Selecting Position Sensors in High Vibration Environments – the Do’s and Don’ts

Mei 9, 2012

Machines that are subject to harsh or prolonged vibration present challenges for many components – none more so than position and speed sensors. This article lists 10 simple rules for design engineers when selecting position and speed sensors that must cope with shock or vibration.

There are many examples of harsh shock and vibration environments: off-road vehicles, airborne avionics and mining equipment. There are also some less obvious examples such as pumps and refrigeration plant, where the vibration is less extreme but persists over many years. Of course, characteristics will vary from application to application but generally all environments with vibration or shock can present significant problems for electrical control systems, particularly position and speed sensors.

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The imaginary hacker

Mei 9, 2012

Under recent economic conditions, it is understandable that a control-system cyber-security audit is not the top priority for many plant operators. Less staff due to layoffs and deferred maintenance can present a clear, tangible threat to operations. Too often, “the imaginary hacker,” discussed in many papers and blogs, is often considered as a non-credible threat. No matter how many blogs, magazine articles and white papers are written, a real credible threat to a refinery or petrochemical facility from some vague person or organization seems “imaginary” to those controlling plant budgets.

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