Recently we've had a couple of stainless steel (409) subsurface transformer tanks corrode through and fail. The transformers are only 3.5 yr old. They're located in a concrete vault and have standing water around them pretty much 24/7. I'm not sure whether to install CP and/or change our spec...
Gents,
I'm not a corrosion engineer, I'm an EE, but recently we've had a couple of stainless steel (409) subsurface transformer tanks corrode through and fail. The transformers are only 3.5 yr old. They're located in a concrete vault and have standing water around them pretty much 24/7. I'm...
I've heard the terms "Grade A Voltage Range" and "Grade B Voltage Range" used to differentiate between the fluctuations in voltage between what the utility delivers to the customer and what the range of voltage certain equipment can operate at. Typically a utility will provide plus or minus 5%...
I remember browsing a thread that talked about a case study detailing the existence of high neutral current within an industrial building that caused multiple motors to subsequently fail. Does anyone remember the thread or could provide me with that study? I think it was started by a member...
I have a table that our power co uses for wind load calcs for wood poles of different types and classes. I'm wondering if anyone can tell me how these were calculated. Per the CPUC GO 95 (State of CA) we are required to use a safety factor of 4 for class "A", SF of 3 for class...
Our utility offers residential developers an option of (for a fee) having subsurface single-phase transformers installed instead of pad mount ones. I’ve been tasked with evaluating the cost differential. I know there is the most obvious incremental cost difference of the sub vs pad, but I was...
I would like some information regarding connecting 3 phase, 21 kV grd Wye-Wye transformers in a common neutral system. I contend that the 500’ UG feed from the OH line should be 4-wires, bringing the neutral wire to the Ho lug on the transformer and connecting this to the grounding rod as well...
Does anyone have any info on a URD design class or some good literature worth it's weight? I'm a new engineer and I need to come up to speed. Class/text should cover all aspects of design from a utility compmany's perspective; loop feed vs radial, design considerations for locating pad mount...
I’ve been tasked with providing auxiliary power to a materials yard directly adjacent to our existing 69 kV to 21 kV substation. The existing ground grid within the substation extends 3 feet beyond the fence. The materials yard will house 240 volt lighting and a future job trailer. I estimate...
