It is currently Mon Sep 27, 2021 6:13 am



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: S&C PHM padmount switches
PostPosted: Fri May 28, 2021 7:46 am 
Sparks Level

Joined: Thu Apr 18, 2019 11:42 am
Posts: 59
Folks,

Since PMHs have inter-phase barriers, chances of 3 phase bolted faults are pretty low (15kV rated system). What is your SOP for AF studies in this situation? I currently only have access to SKM (no ArcPro). Do you use the 3 phase calc's or calc using single phase values?

Thanks for the feedback,

Mike


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: S&C PHM padmount switches
PostPosted: Mon May 31, 2021 8:50 am 
Plasma Level
User avatar

Joined: Wed May 07, 2008 5:00 pm
Posts: 855
Location: Rutland, VT
I think you will find that the incident energy levels will be low based on phase separation distances and fault currents. One thing to consider is that since this is utility equipment and voltages, you should consult OSHA 1910.269 Appendix E for doing an arc flash assessment.

_________________
Barry Donovan, P.E.
www.workplacesafetysolutions.com


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: S&C PHM padmount switches
PostPosted: Mon Jun 28, 2021 6:48 am 

Joined: Mon Dec 03, 2018 11:09 am
Posts: 8
PMH-style switches can have high incident energies. EPRI and PG&E have tested a lot of these units. The barriers are good at preventing a phase-to-phase fault, but a fault can start as a single-phase fault and propagate to multiple phases. What happens is that the cabinet fills with hot gases. Those cause a flashover on a bus-support insulator on adjacent phases. This can take tens of cycles. We've also seen evidence of this from a unit from the field that was involved in an accident.

These switches also have high incident energies because they are an HCB configuration. In fact, test results show incident energies are up to 2X worse than the HCB model in IEEE 1584-2018.

For more information, see these papers:

* https://distributionhandbook.com/papers ... ission.pdf
* https://distributionhandbook.com/papers ... s_2021.pdf


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 7 hours


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883