Arc flash analysis

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jimbo123

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A company plans on having a arc flash study, labeling equipment . How does anyone who is paying for this know they are getting a complete study ? Also what is the company's responsabilty for gathering information ,data , equipment ?
Should the provider go to the site to confirm all or any information given to them from the customer ? What should he be expected to do in the field before he starts the his calc's ?

What should be confirmed before coming to a agreement for the work ?
Anyone who has knowledge of this work is welcome for his or her's input .
 
This is the most important question to be asking at this stage for your plant, this is where many plants make a critical error if not being specific about the requirements. I have seen many facilities just put out an RFQ for an arc flash analysis, and get some horrible studies from low bidders who have no idea what they are doing, they just plug numbers into a calculator thinking that is all that is required. The result is data and labels that are in some cases too conservative (Putting people in unnecessary PPE) and also in some areas not having the right values, putting people in inadequate PPE (Endangering lives) because they did not look at different operating modes, motor contributions, and worse case Ei's (Which is often at lower arcing currents, not always the highest).

IEEE 1585 has very specific requirements, and I suggest looking at those and including them as part of your RFQ. Also get references and qualifications of the bidders. The most important part of the entire process is the data collection. The data used is the basis of the results, labels, PPE requirements, and your entire safety program, so it better be accurate. The data collection is about half of the labor hours ($$) so some plants save money by doing that themselves using data collection sheets provided by the company doing the study. Also keep in mind the entire study is based off assumptions of times your breakers trip so if you have not done testing (As required by 70E) to verify they trip in thier required bands, the study is worthless.

Here are the basic elements that need to be in your RFQ.

The analysis shall consist of the following:
1. Field data collection by qualified personnel (as defined by NFPA 70E).
2. Data entry and system one-line modeling in commercially available power system software.
3. Model verification.
4. Short Circuit and equipment verification study.
5. Protective device coordination study.
6. Arc flash hazard study.
7. Detailed report and findings of the analysis.
8. Electronic copies of the Project Report and the System Modeling File.
9. Review of a draft copy of the report and presentation of the final copy of the report in person, via teleconference, or via teleconference and web conference.
10. Hard copies of the project report (note all printing, postage, etc.) shall be included in proposed project pricing.

You are required to update the study every 3 years or if any major changes are made to your system, so you may want to include that as part of the RFQ, and be sure to get an electronic file of the study so you can update in the future should the contractor go out of business. ETAP, SKM, and Easypower are the most common programs to use so if you have the files anyone with the software can make changes for you in the future.

I have a sample RFQ you can use but it is too large to be attached, PM me you email address and I can send it to you if you like.
 
zog said:
The data collection is about half of the labor hours ($$) so some plants save money by doing that themselves using data collection sheets provided by the company doing the study.
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Let me add that the data required will include, as a minimum, the following:
  • An accurate one-line or riser diagram, showing all panels and all power sources.
  • The sizes and lengths of all feeders.
  • The model numbers and settings of all overcurrent devices.
  • The available fault current from the utility.
  • The model number(s) and ratings of all backup power sources.
  • The HP ratings of all large motors ("large" being a matter of some debate, but I would say 1HP or higher), and the power source (panel) supplying each motor.

 
charlie b said:
Let me add that the data required will include, as a minimum, the following:
  • An accurate one-line or riser diagram, showing all panels and all power sources.
  • The sizes and lengths of all feeders.
  • The model numbers and settings of all overcurrent devices.
  • The available fault current from the utility.
  • The model number(s) and ratings of all backup power sources.
  • The HP ratings of all large motors ("large" being a matter of some debate, but I would say 1HP or higher), and the power source (panel) supplying each motor.
Click to expand...

... one clarification or adder is to get the Utility overcurrent protective device info, in addition to the contribution.
John M
 
When the contractor wants a company to gather information not on the drawings such as cable lenghts ,impedances of trans. , manufacturer of fuses and breakers, settings of devices. The latter seems more for the contractor , we don't know if any settings are correct. Is this normal request ?
We are to install the arc flash hazard warning labels.
We are to obtain the short circuit current available and x/r ratio at the companys incoming sources information from the local utility.

does it matter what software they use?
 
jimbo123 said:
When the contractor wants a company to gather information not on the drawings such as cable lenghts ,impedances of trans. , manufacturer of fuses and breakers, settings of devices. The latter seems more for the contractor , we don't know if any settings are correct. Is this normal request ?
Click to expand...
Usually the company will determine in the bid who is to gather the data. Are you the company or contractor? Don't worry about the settings, if you use that RFQ I sent you the contractor should do a PDC study first, determine the correct settings and provide the setting with the arc flash analysis based on those settings.
jimbo123 said:
We are to install the arc flash hazard warning labels.
We are to obtain the short circuit current available and x/r ratio at the companys incoming sources information from the local utility.
Click to expand...
Again, the contractor should be doing this, unless it was omited from the RFQ.

jimbo123 said:
does it matter what software they use?
Click to expand...
Yes and no. As long as they are using some real software it does nto matter. I prefer SKM, but easy power and ETAP are also good. If they are using some crap calculator or unproven software out there, you better find a new contractor.
 
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