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Hi All, Back in October I got a maintenance report on a Vertiv CP70Z 60 kVA UPS that said it had evidence of tin whiskering and needed cleaned. A batch of CP70Zs a few years ago had some metallurgical fault on the inverter bridge that allowed tin whiskers to form and grow long enough to clear...

I think a periodic refresh could help - although if there's been any permanent sulphation then it won't come off. Before that can happen, the RE has to agree that there's a problem.

This situation has dragged on a bit so I'm wondering if anybody can check my reasoning here. It turns out the measurements were wrong - very wrong - and it nows appears to be "impossible" to take a correct impedance measurement as some kind of buildup or corrosion has happened on the terminals...

Well, what I described was based on what the recalcitrant engineer told me. I've phoned up the contractor and they said it's conceivable so they are investigating & will get back to me soon. I doubt they will get into trouble for it, that doesn't seem to be the way things work where I am.

Last week I checked a workshop that had a beeping dekstop UPS and found it was in discharge mode and all the 30 mA RCDs built into the small power sockets had tripped. Not all of the sockets had anything connected to them. I absent mindedly reset them all and left it at that, but over the...

Thanks for the replies - I really appreciate it because I did wonder if I was missing something. The responsible engineer finally agreed to investigate after I started cc'ing a lot of important people in my emails to him. It looks as if there is something (I don't know what, this guy won't let...

Hi chaps, Just wondering if I could get some independent people to confirm my thinking about a problem? I have a "temporary" installation that's been deployed for the last 1.5 years since the proper charger and battery failed. It's always been slightly undervoltage at about 116V for 9 x 12v...

Well, it's good that it's a step in the right direction. I get frustrated at the money we keep wasting replacing assets we shouldn't have to. I was offered the job of being trained to write the data analysis scripts, but I handed my notice in instead. My next job pays quite a lot more and I...

Hi All, Thanks for the responses. CMMS = Centralised Maintenance Management System EAM = Enterprise Asset Management SLD Single Line Drawing TRAM = Throughput, Reliability, Availability, Maintenance (Design come up with a document estimating plant throughput and how reliable it is when they...

Hi All, I'm not 100% sure if this is the appropriate board, so my sincere apologies if I'm asking in the wrong place. I currently work on a very big site, and my biggest bug bear ever is the total lack of information. I have done some reading on this site and others, and I get the impression...

Hi ScottyUK, I know this was a long time ago, but I never got an email about a reply so never checked. Thanks for responding. Guess I'll never know what it really was, but sounds like your answer could be plausible. Can't open the cabinet while energised for safety reasons, nobody ever shared...

Morning all, I got called into work yesterday to attend a breakdown on a Siemens MasterGuard 125 kVA machine from 1999.. It had failed overnight and automatically switched itself to external bypass. The external bypass has a separate feed to the internal bypass. During investigation I found...

Is £42k low for the UK or outside the UK? My employer insists it's above average. I think the different figures you can find online are of questionable quality.

Afternoon, Who writes and approves the permits? Is the issue definitely the permit, or is the contractor drilling in the wrong place? I am not 100% of the underlying UK legislation or even if it would apply to your situation, however my understanding is that the owner of the site is the main...

Afternoon, TYVM for all the replied - it's appreciated. I feel a little more confident reading them. I have been job searching and have some interviews coming up for "Senior Engineer" roles at threee different firms, all in about the £60k range. These are mostly design roles, so I'm a little...

In a nutshell, the DNO can supply you with reactive power, but this costs them extra so they pass the charge on to you - higher current and losses to deliver less real work. It would be interesting to hear an explanation of why it's so inconvenient for DNOs since I personally don't know why...

That makes a lot of sense. Thanks!

AH yep that makes sense. I usually think about flow rates based on safety case rather than batch or process so it didn't immediately click. Thanks for explaining.

Thanks for the explanation! I mainly work on vent systems ATM as an electrical engineer, so I don't know so much about the mechanical implications. I usually get designers to tell me or work out lowest "safe" flow rate and we set motor speed to reflect that. We have VSDs on the diesel fuel...

That's pretty interesting, I wasn't aware of that. We don't meter anything where I work so I've never seen a real before/after picture. Do you have anything like that? Not sure what you mean about doing the "same work" though. If a motor's running slower, then surely it's performing less work...