mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
Dear forum folks,
I have a situation that is very typical in industry - that I'd like to get opinions on.
The system is a 3000 kVA transformer/switchgear lineup, 480 Volt, 5000 amp.
The secondary of the transformer has 180 calories/cm^2 of incident energy (IE).
The main breaker occupies section 1 of this metal-enclosed gear.
The A&E firm I'm doing the Power Study for would like me to post the HRC Dangerous label on the transformer and first section of the gear, making it inaccessible while energized, but post labels on the remaining sections that represent the reduction in IE resulting from adjustments to the secondary main. Their contention is that the cast coil transformer has wrapped/insulated 5000-amp bus that only goes to section 1. Beyond that, sections 2 thorugh 5 only see the load side of that breaker.
A Siemens engineer agrees with that logic, on a personal level, but not speaking as the voice of Siemens.
It's difficult for me to agree with that assessment because there's a 32-foot Arc-Flash boundary around that breaker, and if you're racking out a distribution breaker, you're in that boundary, and you're interacting with that system. But I think the argument could be made that since the Dangerous bus does not enter any of the other sections, perhaps that 5000-amp bus is not being interacted with.
It's easy to be cautious and label everything Dangerous, but it makes the gear impossible to work with. I understand that the gear is not designed to contain the blast of an Arc-Flash, and if it flashed over while working in an adjacent HRC2 section, there could be collateral damage.
So I ask to the froum folks with experience in this area for their opinions.
Thanks for any responses.
John M
I have a situation that is very typical in industry - that I'd like to get opinions on.
The system is a 3000 kVA transformer/switchgear lineup, 480 Volt, 5000 amp.
The secondary of the transformer has 180 calories/cm^2 of incident energy (IE).
The main breaker occupies section 1 of this metal-enclosed gear.
The A&E firm I'm doing the Power Study for would like me to post the HRC Dangerous label on the transformer and first section of the gear, making it inaccessible while energized, but post labels on the remaining sections that represent the reduction in IE resulting from adjustments to the secondary main. Their contention is that the cast coil transformer has wrapped/insulated 5000-amp bus that only goes to section 1. Beyond that, sections 2 thorugh 5 only see the load side of that breaker.
A Siemens engineer agrees with that logic, on a personal level, but not speaking as the voice of Siemens.
It's difficult for me to agree with that assessment because there's a 32-foot Arc-Flash boundary around that breaker, and if you're racking out a distribution breaker, you're in that boundary, and you're interacting with that system. But I think the argument could be made that since the Dangerous bus does not enter any of the other sections, perhaps that 5000-amp bus is not being interacted with.
It's easy to be cautious and label everything Dangerous, but it makes the gear impossible to work with. I understand that the gear is not designed to contain the blast of an Arc-Flash, and if it flashed over while working in an adjacent HRC2 section, there could be collateral damage.
So I ask to the froum folks with experience in this area for their opinions.
Thanks for any responses.
John M
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