Some concerns about a 20x25 room with one exit and a
150kVA pad mount xfmr boosting 208 => 480 in Data Center
What is the actual Arc Flash danger here?We only have one exit door in the server room.
Server room is classified as S2 Low Hazard Storage because the xfmr, but the batteries on the UPS could bring it up to H3 - which would require less than 25' to the exit door.
There is no present danger in my opinion, but there is a question of whether this is intrinsically unsafe to have the xfmr in a room that may have unqualified people in it.
If the doors on that xfmr are not opened, is there a danger to anyone in the room?
I've put my hands on the effects of AF when it happened with the doors shut, and its usually holes burned in the cabinet, but the doors didn't get blown off or anything.
I've got to call square d and ask them
The next OCP before the xfmr is a 400a main disconnect. The xfmr is tapped from that bus.
The only load on the 480 [secondary side] is a pair of intermittently used 90a 3p cbs
square d 35149-17232-023 150t3hb instruction manual three phase insulated transformer
Watchdog® Low Temperature Rise
• Designed for low energy losses at loads greater than 50% of
• Extra long life expectancy using 220 oC insulation system
designed for full load operation at a maximum temperature rise
of 115 oC or 80 oC instead of 150 oC.
• Continuous emergency overload capability of 15% on 115 oC
rise and 30% on 80 oC rise.
NOTE: These products are obsolete and can no
longer be ordered. The information in this table
is for reference only.