We have two separate 15kV feeds running into an electrical vault. The conduits run parallel to one another but they will feed two sides of a main tie main lineup. Because of the way they came out of the source vault, they need to cross in order to land on the proper load interrupter.
We would...
I have seen a number of installs of 15kV cable with a grounded tape shield on each conductor. In all of these installs, there is not a separate ground conductor pulled through the conduit.
On a new job, the engineer is calling for a separate ground wire. Can someone point me to the relevant...
The other concern is Arc Fault. High Short Circuit ratings mean more damaging faults, even if you have equipment with enough withstand.
In our "discussions" about this with my EE friend (and don't get me wrong - I have a lot of respect for this guy) I argued that the tradeoff in safety and...
Even though your breakers all add up to 375A, they don't necessarily draw that much amperage. For example, it is not uncommon for a 20A receptacle breaker to only have 360 VA applied in the load calculation (3 Amps at 120V) if it a dedicated GFI circuit for example.
If you put in a 125A fuse...
I used to work with an EE who claimed that the impedance losses from the transformer are overlooked and shouldn't be. According to him, at full load, the voltage drop is about 2/3 of the impedance percentage.
Because of this, he would always specify very low impedance transformers. I argued...
The factory provided the wiring, but it was landed in the field. They provide instructions requiring 5" clearance.
Isn't that like me putting in a 100A panel with 200A of load and telling the home owner to never run everything at once?
We had a fault in an ATS last week. Upon inspection, we found that a wire in one of the cabinets had burned through and arced in a few places.
This is a 12.47 kV ATS (nominal 15 kV). The wires feeding the loads are large 15 kV rated cables. There are also smaller (#4) wires that feed the...
Conventional wisdom has been that switchgear is more robust and more reliable than switchboards - and that it should be specified for critical and industrial applications.
However, I know that there have been a lot of changes in molded case equipment over the last few years and I'm wondering -...
Thanks Bill - great info.
I just spoke with the Generator manufacturer and they said very similar things.
For what it's worth, the generator was turned off and there's no outward indication of major failure. There were flames coming out of the alternator during the event.
This is a rather...
One of my clients had a 200kW generator get back-fed from the utility, which caused the alternator to catch on fire.
They're talking about having us replace the entire generator with the same unit (it was relatively new). I'm wondering - couldn't we just put a new alternator on it?
Is it...
I wanted to follow up not that this has been figured out.
Turns out there was a short in the CT section of the secondary switchgear. What was very helpful was the assertion from several of you that it sounded very much like a hard secondary fault.
Thanks again for all of your help on this!
I looked inside this unit and the batteries were fine, but the board and coils immediately connected to the incoming and outgoing power were completely cooked. It looks like the fire started somewhere in that area.
A facility manager I work with recently had a small APC UPS catch fire and burn up. A week before, they had an SCR on a large UPS fail.
We suspect the cause to be some sort of power quality issue on the distribution system. The issues have come up since introducing some large, non-constant DC...
