Recent content by ZeroSeq

Hello, Recommended practices and calculations for cable shield grounding and induced voltages are readily available for single conductor cables. However, I'm finding a difficult time in finding a similar reference or standard for 3-Conductor or trefoil cable arrangement (e.g. Teck). Does anyone...

Hi mLp85 - should the vector group you're referring to be "Yyn0" and not "YNyn0"? Wouldn't the Z0 of a YNyn0 be exceptionally low, and the tank effect being a consideration only where one of the Y-windings is open circuited (e.g. Yyn0)? Just bringing to back to my initial inquiry, here's a...

Good point, although 4kHz in this case.

Hello, I have an interesting current waveform at an industrial facility that appears to be quite sporadic (potentially occurring only once or twice a week), which very clearly has high harmonic content. This oscillography is only captured as there are fairly sensitive alarm elements programmed...

Thanks prc - is that 0.8-0.9 per-unit Z1 the same for a Yynd (floating primary)?

Thanks for the reply. So the buried delta will facilitate current flow for a secondary SLG fault? The question I would then ask is how would you calculate the zero sequence impedance for the SLG fault? If the buried delta (obviously rated much lower than the primary and secondary) facilitates...

Hello, For a Y-Yg transformer (primary floating, secondary solidly grounded), a secondary ground fault will have no current flow as there is no path on the primary windings for the necessary congruent current to flow. However, will this still be the case for a transformer with a buried delta...

Hello, Two years ago, I had a part of the slab of my house hydraulically jacked based on a recommendation of my contractor who was constructing a new bathroom. The following year, we had a significant amount of rain, resulting in a raising of the slab by over 2". Aside from the obvious...

I wonder how that works within the boundaries of engineering codes of ethics. Generally an engineer should ensure fair (market value?) remuneration for the professional service offered. As an example, here is an excerpt from the APEGBC code of ethics: (5) uphold the principle of...

waross pretty much nailed the intuitive explanation. The definition of "rotor angle" is the electrical angle between the machine quadrature axis and the synchronous reference.

Study work in question would be for power system related analyses (harmonic studies, transient motor starting, loadflow, short circuit calculations, reliability assessments, etc.). The study work is not directly related to an installation, but produced mainly to give an industrial customer...

Thanks for the replies. I've gone through several state engineering acts and yes, the provisions are generally congruent. However, where I'm not getting a clear consensus on is where the industrial exemptions apply. I have rarely, if ever, seen study work (ex. FEED, risk assessments...

Hello, I'm wondering if anyone knows off the top of their head or can point to the specific engineering act clause stating what work *specifically* requires the seal of a professional engineer. The work I'm looking for clarification on is some technical study work not related to any type of...

prc, this formula is very useful, thanks for the insight. Would you happen to know where it is cited (ex. J&P Transformer Book, Electric Power Transformer Engineering, etc.)?

Alternatively - where LVPCBs are already used, transfer systems can be programmed within a PLC or microprocessor relays for controlling the breakers. Usually provides the best flexibility and highest rating.