IEEE Std 693-2005, Recommended Practice for Seismic Design of Substations

I am currently researching IEEE Std 693…

One of its recommended shaker test methods for power equipment is to use a “sine beat” acceleration time history. The main frequency is selected as the equipment’s natural frequency.

The minimum number of beats is 5 with a minimum of 10 cycles within each beat pulse. There is also a pause between beat pulses.

A problem with this approach is that the corresponding displacement has a stair-step effect for a whole number of cycles. This offset disappears if an extra half-cycle is added. An example would be to use 10.5 cycles.

Here is a slide presentation:  IEEE_693_sine_beat.pptx

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I have added a function for generating IEEE sine beat time histories to the Vibrationdata GUI package.

Matlab script: Vibrationdata Signal Analysis Package

>> vibrationdata > Miscellaneous > Generate Signal > IEEE std 693 Sine Beat

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The package also has a function for generating the Required Shock Spectrum (RSS) levels.

>> vibrationdata > Import Data to Matlab > SRS Library Array > IEEE std 693 RSS, Various

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References

An Implementation of an Earthquake Test, According to the Sine-Beat Method: Sine_beat.pdf

Seismic Considerations of Circuit Breakers: Seismic_Considerations_of_Circuit_Breakers.pdf

IEEE 693 Seismic Qualificaiton of Composites for Substation High-Voltage Equipment: 13_2306.pdf 

– Tom Irvine

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