You had also best think of what you are going to do with the energy the elevator is going to regen and try to feed back into your inverter. You're going to have to dump that excess somehow.
I don't live in the IEEE / NEC world but there has to be millions of breakers rated to at least 48 volts installed in all the various telcos which use -48 volts as their standard distribution voltage with exchanges.
And a DIN rail breaker mounts on a piece of DIN rail, you don't need a special...
Veritas, look at the 100 kA point and go up to the orange line and then across, it looks like you get approximately 220 kA projected onto the left hand scale. As this is way higher than the calculated symetrical fault current it can only lead to one conclusion :)
Bill, one of the first suggestions made was for a load bank to be installed in the generator room and switched in whenever the regen exceeds the load. Haven't heard from the client so they are still mulling over the initial report.
Muthu, there's no braking resistors on the drives and no room to install any, and that power has to go somewhere. One option we are kicking around is a load bank installed near the generators that can be quickly electronically switched in when required, but as I said this is very early days and...
Yeah, big building Keith, and I've only had a cursory look and kick of the tyres so far. 24 lifts fed from multiple switchboards. They are doing a lift upgrade program. The previous lift system used braking resistors and the new system was put in place for power efficiency. The discovered this...
A follow up question. I've come across a site where the lifts are fed via a regenerative drive. When a lift is descending then there's power being fed back into the grid and all is fine. The issue is when the power fails the site then transfers across to on-site backup generators. Now when a...
Gunnar, I haven't gotten around to buying one as yet, although I keep promising myself that I'll get around to it. Unfortunately I was bought up in the time where we cut off the earth pin, placed the oscilloscope onto a plastic milk crate and then were very careful about how we changed the...
jraef, thanks for your post and the information, especially the interesting fault scenario at the end. Something else that I'm going to have to throw into the mix.
Mark, I'm based in Melbourne. I used to help out Vectek (I hope I have that name right) with UPS issues many years ago and would fly over on occasions to give assistance. I still know a few of the olds and bolds from those days and keep in touch once in a blue moon.
As to the problem, one...
Mark, thanks for the reply and I have to do a ROFL. On Friday I was searching around for papers to read and came across some from AuCom which mentioned your name. The name immediately set off some bells in my head but I couldn't work out from where. I hadn't posted over here for three or four...
Bill, as far as I know, and that's very little on this job, the soft stop was to reduce water hammer.
OK...I can see now that I've made a few rookie mistakes. Firstly I've posted way too much information and detail in my OP. Engineers are of course going to pile in and diagnose the issue and...
Thanks, Keith. From the information that I've been able to gather (not much) there was at least one occasion where the fuse blew on the white phase and on other occasions on the blue phase. I should have mentioned that the soft starter was replaced, after failure, on four occasions, not just...
I have been asked to do a review of an incident at a site that occurred over 6 months ago and where the site conditions have changed considerably since. The information gathered from the site, by others, during the events was sparse.
The site has a 2 pole, 400V, 30 kW pump which was used to...
Something that I was notified about today and thought may be of interest to some on the forum. Haven't posted here for quite a while and had to go looking for my login details.
This is an excerpt from a notice that Schneider has sent out regarding Masterpact NW Circuit Breakers (3P, 4P, 6P, &...
I doubt there will be any problems with the heating controller under this scenario, but there certainly may be an issue with the load elements. Under the unbalanced load condition, and a floating wye point, the voltages across each leg of the load will be at different potentials as the wye point...
