IEEE 693

Key takeaways

IEEE 693 belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IEEE 693 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IEEE 693 from memory before moving on to harder problems.

Reference excerpt

The IEEE 693: Recommended Practice for Seismic Design of Substations. is a Institute of Electrical and Electronics Engineers standard. This standard is recognized also by American National Standards Institute, and is used mainly in the American Continent. The goal of the standard is to provide a single set of rules and regulations that cover the seismic design of both new and existing electrical substations, hence leading to standardization. The standard provides the minimum requirements that the design of an electrical substation (except nuclear power plants) must adhere to. The norm includes the design of circuit breakers, transformers, disconnect and grounding switches, instrument transformers, circuit switches, surge arresters, and other equipment.

Contents The norm contains the 8 chapters named below:

Overview Normative references Definitions, acronyms, and abbreviations Instructions General Specifying this recommended practice in user's specification Standardization of criteria Selection of qualification level Witnessing of shake-table testing Optional qualification methods Qualifying equipment by group Inherently acceptable equipment Shake-table facilities Equipment too large to be tested in its in-service configuration Report templates Installation considerations General Equipment assembly Site response characteristics Soil-structure interaction Support structures Base isolation Suspended equipment Anchorage Conductor induced loading Interconnections with adjacent equipment Observed component displacements Decoupling equipment through flexible bus-work Conductor installation Short-circuit loads Wind and ice loads Qualification methods: an overview General Analysis methods Static analysis Static coefficient analysis Response spectrum dynamic analysis Time history dynamic analysis Testing methods Special test cases Qualification method for specific equipment Functionality of equipment Qualification by seismic experience data Response spectra Damping Design considerations Structural supports, excluding foundations Foundation analysis Station service Emergency power systems Telecommunication equipment Seismic performance criteria for electrical substation equipment Introduction Objective Seismic qualification levels High seismic level Moderate seismic level Low seismic level Projected performance Performance levels High Moderate Low Seismic qualification High and moderate seismic qualification levels Low seismic qualification level Selecting the seismic level for seismic qualification The norm specifies 3 seismic qualification levels (high, medium, low). The Zero Period Acceleration (ZPA) (a.k.a. Peak Ground Acceleration) for the high and the medium qualifications levels are set to be 0.5g and 0.25 respectively (no calculation is required for equipment with "low" qualification), where g stands for acceleration due to gravity. The Peak Acceleration (i.e. the peak of the Response Spectrum) at 2% damping is lower than 1.65g and 0.85g for high and medium qualification respectively, with the cutoff frequency defined as 33Hz. The qualification is allowed through one of the following:

Shake Table Testing Calculations Static Response Spectrum Time History Experience (with justification) The norm suggests that most equipment in the same area be given the same qualification level (for interchangeability and redundancy).

Levels The norm suggests two levels for qualification:

Performance Level: Typically used for shake table tests Design Level: Half the values of performance level, typically used for calculations The Peak Ground Acceleration (PGA) suggested for Horizontal Design level (vertical is 80% of horizontal) are:

High Design Level: 0.5g Moderate Design Level: 0.25g Low Design Level: 0.1g

Useful information The definition of rigidity is 33Hz and above. Triaxial combination is to be used for Response Spectrum analysis The Required Response Spectra (RRS) is for free field (ground) conditions and does not include the influence of the dynamic characteristics of the building. To account for the building response (for qualification of equipment mounted within the building), two options are provided A 2% damped response spectrum that represents the position-specific response within the building to the unreduced (elastic) design spectrum as determined according to the building code shall be provided. Multiplying the RRS by a factor of 2.5 for the purpose of equipment qualification.

History The first version of the standard was released in 1997, with a revised version released in 2005 and later in 2018.

Annex There are a total of 22 annexes in the standard, 19 of which are normative, and the other 3 are informative.

References

Worked examples

Example 1 — a first encounter with IEEE 693

Start with the simplest possible case. Write down what IEEE 693 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to IEEE 693 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about IEEE 693 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of IEEE 693

In research: IEEE 693 appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses IEEE 693 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: IEEE 693 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Institute of Electrical and Electronics Engineers, so understanding it makes those chapters shorter.
In everyday life: Look for IEEE 693 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study IEEE 693 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IEEE 693 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain IEEE 693 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IEEE 693 in simple terms?

The IEEE 693: Recommended Practice for Seismic Design of Substations. is a Institute of Electrical and Electronics Engineers standard. This standard is recognized also by American National Standards Institute, and is used mainly in the American Continent.

Why does IEEE 693 matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study IEEE 693?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on IEEE 693.