Looking over a power monitoring dataset recently; we came across a site with a dual personality. The site in question had low total harmonic distortion (THD ~ 1.5%) from 4/1/17 up until 4/10/17 (specifically, at 2:00 pm). After that, the THD fluctuated much higher, rising as high as 5.4% (outside of manufacturer requirements for medical imaging equipment).
A closer “before / after” look at the voltage and current waveforms provides more evidence, with visible notching on the voltage waveform “after”; monitored current showed some noise but was similarly low.
Individual harmonics similarly supported the findings of the THD log, with all harmonics higher, and 5th harmonics exceeding 3%.
Finally, the “before after” affect was also seen in the Neutral-Ground voltage – with noise voltages evident although the lower frequency voltages were not much higher.
The funny thing is that the RMS voltage and the current of the device under test were not significantly different before / after the 4/10/17 date, in terms of RMS level or in terms of stability: sags, swells or fluctuations.
So what’s the scoop? We’re not on site, but odds are good that some facility load (we’re betting air conditioning, but could be other facility loads) got switched on at this time. Alternately, perhaps the facility transitioned to an alternative power source. But whatever the reason, this is clearly a tale of two power systems, and we’re curious about it!
I found out this morning that Joe Briere of Computer Power Northeast passed away back in March – obituary.
Joe and I go back a long ways. When I worked at Philips Medical in Shelton (pre-1995) he stopped in a few times to see if there was any business there; he was plying his trade as a power quality consultant in the medical imaging field, doing a lot of work with Siemens Medical, so it was natural that our paths would cross. He was one of those “I’ll help you with your power quality issues and maybe sell a transformer, voltage regulator, power conditioner, Uninterruptible Power Supply, or Surge Protective Device along the way” kind of consultants that inevitably made a lot more money than me (who chose not to sell or rep products, just provide technical services). He was always a straight-shooter, never found him to oversell or over-promise, and was a hands-on guy who knew his way around grounding, the electrical code, isolation transformers, etc. We did not agree on everything, but I always respected his opinions and experience.
For a few years there (2001 – 2003) Joe and I would often find ourselves meeting at Siemens trouble sites across the country as the service organization tried to get a handle on power and grounding issues, so I got to know him pretty well, poking around hospital electrical systems and sharing a beer and a meal afterwards.
Have not been in contact for many years (my last contact with Joe was 2003, and with Computer Power Northeast was 2009) but I’d pop over to the website now and then to see if they were still in business. Joe was probably retirement age when I started working closely with him, and reportedly kept busy well into his 80’s. His business partner called for a little consulting project this morning and shared the news.
Was a long time ago in a galaxy far, far away. Power Quality Consulting was kind of the wild west back then and the folks who knew what they were doing, were not afraid to open an electrical panel and make some measurements, and could sort out technical issues that left others scratching their heads were a rare breed. RIP, old friend.
I just sent a client a document from a seminar that I created and led in 1996. (The seminar client is long out of business).
It’s nice to be (a) the old dog who was around back in the day, and (b) a bit of a digital pack rat. Also interesting that the technical issues of 2017 are no so different from the technical issues of 1996.
Here’s a snapshot of that document (pretty slick for 1996, no?) – and no guarantees that the IEC / UL references or requirements are still valid. But the concept – that measuring ground resistance with a low current ohmmeter is going to give you sketchy results – remains valid.
Power Quality for Diagnostic Medical Imaging Systems by South Carolina Electric & Gas (SCE&G)
Normally these sorts of utility “power quality” documents are fairly cursory, but this one is comprehensive and well done. Recommended!
Yes, these things can be glorified sales pitches. But hey, FREE and CONTINENTAL BREAKFAST.
When: November 10, 2016
Where: Radisson Hotel
50 Morgan Street
Hartford, Connecticut 06120
1 (860) 549-2400
More Info (PDF)
Heard yesterday on Fresh Air: Aging And Unstable, The Nation’s Electrical Grid Is ‘The Weakest Link’
In her new book, The Grid, Gretchen Bakke argues that the under-funded power grid is incapable of taking the U.S. into a new energy future. She explains the challenges to Fresh Air‘s Dave Davies.
Just ordered a copy online; was a great interview and sounds like a wonderful book, dealing with the realities of balancing nearly unlimited, yet inconsistent renewable power sources (solar, wind, etc.) with the reality of consumer and commercial demand.
I confess to being a little curmudgeonly about issues of power usage, renewable energy sources, attempts to encourage consumer energy savings, etc. and this book gets to the heart of a lot of that. Really looking forward to this read!
Popped upon my social media feed this afternoon.
Price Chopper is running a sponsored ad touting their support of Riverfest, at the same time the cancellation of said event is all over most social media feeds.
It’s one of the reasons I’m a bit hesitant to embrace scheduled, planned social media posts, and have a more hands-on, direct approach. Because one never knows – some sort of political incident, tragic accident, hilarious meme, or other news story could crop up and the juxtaposition of a social media post (sponsored or otherwise) with a problematic news story could result in a social media fail. Even if there’s no direct connection (as there is here), promoting a fun and games event in the wake of a crime, attack, or natural disaster is at best, tone deaf.
I do schedule some things, but I do so judiciously, and keep an eye on things – ready to pull the plug at any time. And I notice what companies and organizations seem to be managing their social media somewhat robotically or blindly – and make some assumptions about the entity’s customer service accordingly.
We’ve spent some time recently putting together a spreadsheet for a client to review advance reservations for a local Dinner Train. It is intended to help management and marketing look down the road to fine-tune marketing and social media efforts.
The magic is the use of templates and macros – the spreadsheet is designed to quickly and easily import data obtained from an eCommerce platform (Shopify), and with the push of a button, to sort, filter, and copy the data so that the charts are automatically produced – in less than a minute, and by users who are not spreadsheet gurus.
Step-by-step instructions embedded into the spreadsheet to ensure non-expert users and/or new users can work with the spreadsheet.
We set the spreadsheet and graphs up just once – and through macros, paste new data into the spreadsheet, so that the graphs are updated and ready for use without touching them at all.
Just one of our many skills and services – if you have data that you’re having trouble making good use of, or are spending too much time on repetitive tasks to get your data into useful form, give us a shout. A few hours of work setting up an automated spreadsheet can yield huge savings down the road.
Siemens Healthcare Becomes Siemens Healthineers
We’ve been working with Siemens since 2001. Somewhere along May 2009, we transitioned reports and templates from being branded as Siemens Medical Solutions to Siemens Healthcare. So I suppose it’s about time for a bit of rebranding. Pretty minor change for us (the word “Healthcare” appears a grand total of 2x in the report templates we start from.
The new name embodies the company’s pioneering spirit and engineering expertise in the healthcare industry. It is unique and bold and gives a new identity to the organization and to the people – the people accompanying, serving and inspiring healthcare providers worldwide – the people behind outstanding products and solutions.
Makes me think of Walt Disney and the Imagineers (I’ve recently watched a PBS biography of Uncle Walt).