LV Transformer Arc Flash Labeling

[Nicolas J]

thread238-343771

This a response to a previous thread started by user: alehman (Electrical)(OP)on the topic of finding an easier way to create transformer arc flash labels in SKM that reports that highest shock hazard and respective limited/restricted boundaries. I'm not sure if he ever received the response that he was looking for, but I was unable to add to the thread due to it being closed at this time. I have posted the original question below for reference:

"Using SKM Powertools for arc flash studies and labeling, I've been wondering if there is a better way to handle LV transformers where there are multiple buses in a single enclosure. I usually print separate labels for each bus, which was the suggestion of SKM's technical support. It bothers me to have multiple labels because it is somewhat open to interpretation by potential workers which bus is being worked on. I would feel more comfortable with a single "worst case" label for such equipment. SKM can print labels with line-side and bus data for main-breaker equipment, but I haven't found a way to do this for transformers. Just wondering how others have handled this. "

To answer this question, I would propose the following method:
1. Create a separate Custom Label for the different transformer Primary voltage ratings on your site (i.e 12470, 4160, 480, etc.). Use the clone feature to create one based on your preferred label style for expediency. Make sure to include a note so as to different between these custom labels (i.e. Primary Side or Highest Voltage Rating).
2. Replace the fields for Glove Class, Shock Risk, Limited Approach, & Restricted Approach with static values according to voltage rating of the custom label as follows:
3. Activate (4) blank text fields in the Custom Label Designer. (Clicking the check boxes)
4. Copy the Field Layout Settings from the Glove Class, Shock Risk (Voltage), Limited Approach, & Restricted Approach Fields and past them to the respective new text fields. (Simply press copy & paste button to perform the latter step)
5. Deactivate the original Glove Class, Shock Risk, Limited Approach, & restricted Approach fields, (Uncheck the boxes)
6. Manually enter the new Shock Risk (Voltage) and respective Limited/Restricted Approach per NFPA 70E Table 130.4 (D)(a) & Glove Class per ASTM International ASTM D120-14a – Standard Specification for Rubber Insulating Gloves.
7. Use the respective Label Style that correspondences to the Primary Side or Highest voltage rating of the Transformer(s) that you printing the labels for in the arc flash custom label print dialogue box.

I believe the latter method should be the most efficient in making sure that your labels capture the information for the bus that has the highest shock hazards at these transformers (typically the primary side) which may not necessarily correspond with the one that has the highest arc flash rating (typically the secondary side).

Sincerely,
Nicolas J.

"All things [even the bad ones] work together for the good of those who love [YHWH] God, and are called according to His purpose for them." (Romans 8:28)

 

[wbd]

Why would you label a transformer? Read NFPA 70E-2018 Article 130.5(H). Nowhere is a transformer mentioned in addition to why would a transformer need "examination, adjustment, servicing or maintenance while energized" What is the justification that would be used on an Energized Electrical Work Permit to do energized work on a transformer?

 

[davidbeach]

Removing covers to IR scan the terminations on a dry-type transformer would be an example of work in the vicinity of an energized transformer.

 

[wbd]

Removing covers to IR scan the terminations on a dry-type transformer would be an example of work in the vicinity of an energized transformer.

True and I would think that would be for larger dry types, so one area would be to define what size transformer is being asked about. If it is for IR scans, then I could see it going one of two ways to avoid an energized work permit and the associated issues with that:

1. De-energize transformer, remove covers, energize, perform IR scan, de-energize, re-install covers, energize.
2. If there is an IR scan done, it is most likely part of a PM program, so why not maximize safety and install IR viewports?

 

[Nicolas J]

At our facility, we actually require that all equipment be tested with a contact voltage meter after it has been de-energized and LOTO Devices installed. This is to verify its zero potential state prior to releasing it for work. In order to perform the latter task safely, the personnel are required to wear their Arc Flash PPE during this verification.

Nevertheless, the latter points are all good suggestions. We have actually implemented a program to install IR viewports on all of our transformers above 125KVA.

"All things [even the bad ones] work together for the good of those who love [YHWH] God, and are called according to His purpose for them." (Romans 8:28)