Amend-6 Email 8-22-202 Meter.docx

From: Bill Sent: Thursday, August 4, 2022 9:02 AM To: Zunino Subject: RE: meter

Heather, I attached a graph of a section of the last recording you sent. The graph shows the harmonic content drops when the current increases. I was concerned about the harmonics I was seeing. However, as I said, I thought the X-ray was being used during the time the current increased. You can see the current spikes up and harmonics drop.

Regarding the X-ray power: It’s my view there that the X-ray problems are not related to power fed to the Xray. At least, not based on the power recordings. However, maybe the Xray manufacturer can tell you what sort of power conditioning equipment they’d like installed? It’s possible, future power quality events would be eliminated or reduced to a place where the X-ray would not be damaged? If they can give you some recommendation, I’d be happy to review that equipment and give you some feedback or a scope of work.

As far as the previous damage, if there was an electrical power quality issue or a lightning strike that caused the X-ray to be damaged, it’s likely that it entered the electrical system via the utility or a lightning strike or multiple strikes. However, if this were the case, I’d have expected there to be other equipment damaged. For example, the telephone system, the other X-ray machines, any CT’s or MRI’s and of course, computer-based equipment. If you are aware of any other complaints about equipment failures that took place on or shortly after the X-ray failure, that would indicate an electrical spike of some kind.

Regarding Lightning Protection: Because I mentioned lightning, does the hospital have a lightning protection system installed? If it does have lightning protection and if it’s functioning properly, any direct lightning strike on the building ought to have been conducted to earth with minimal damage to the structure and the electrical system.

Going forward: I understood the cost of the repairs to the X-ray was substantial. If that’s correct, I’d suggest a permanently mounted power quality monitor be installed. I would not necessarily put the monitor at the X-ray, instead at the main gear or very near the main gear. The purpose behind installing a recording power quality monitor would be to have hard data to review if events like above had occurred. This was you could possibly match those events with damage to sensitive equipment. However, it is believed that most lightning strikes are very high frequency. The nature of high frequency is that they travel relatively short distances on wire. Meaning they don’t get very far inside a building electrical system.

Other observations: I believe most people think the steel framework in buildings provides an good path for lightning to be conducted to the earth. That’s not completely true. Just as with copper, when electricity passes through the steel structure, the electricity produces electrical fields around the steel itself. And if the lightning stoke is high frequency, the fields expand and collapse and induce current and voltage in anything ferrous. Also, relative to copper, steel is not very conductive. If you complicate this fact with a poor grounding system, the current will resonate in the steel as it discharges into the earth. This can often take several seconds. During that time, the electrical field is expanding and collapsing and inducing electrical power into anything it can. This is one of the reasons lightning control systems with good grounding are important.

Thanks, Bill