So I was checking out a new large power transformer and I'm wondering in the day and age of Electronic temperature monitors replacing the traditional analog gauges and heaters, why do the CT ratios seem like they are specified for older equipment. The Electronic temperature monitors can accept...
Once in a while I venture outside the comfort zone of utility work where good quality drawings and relay settings are a given. My latest adventure takes me to a water treatment facility that was built over 50 years ago, expanded multiple times and has very poor documentation. I was there to...
I seem to recall there used to be a consolidated list of various relays & types and any manufacturer service advisory or issues list. My google skills can't seem to find.
I had a 40 year old HEA darn near go up in flames today. I was performing function checks, it tripped as expected, I reset...
I was recently doing a relay upgrade on an unusual station that had 2 lines, 2 buses, but only one set of VT's. We were told by system protection that there was a concern about LOP mis-operations on the line that was staying in service. A protection outage was requested to pull all of the...
I had mentioned the very serious issues that have been occurring on the grid due to Inverter Based Resources (Solar and Wind) tripping offline at the worst possible moments, such as after a fault in another generating station. NERC had issued some strongly worded guidelines about fixing the...
I just finished a project upgrading 90's era protection and excitation with modern digital units. We had a very large number of red and green marks on our drawings at the end as the engineering was not exactly complete when handed to us. Part of this were the relay settings and various...
This feature has been introduced in our region and I'm curious if others are utilizing. For many years, digital relays, in our case mostly SEL have been used from trip circuit monitoring, where an input of the relay is wired in parallel with the trip bus. A little logic also containing 52a and...
We recently retrofitted new SEL relays into an existing 15kV Metal Clad Switchgear line up at an industrial facility. The gear was first installed in 1984 and built by an unknown switchgear vendor that did not supply a lot of details with the drawings. The gear has (3) bays that each feed a...
California Facing Largest Power Outages In Its History
"the unexpected loss of a 470-megawatt (MW) power plant, and loss of nearly 1,000 MW of wind power"
Didn't nearly the same thing occur in the UK last year?
UK power outage 9 August 2019
"Just before 5pm, a technical issue at RWE’s Little...
I was doing a drawing review and saw something that caught my eye. A 345kV IPO breaker (intended for 3 ph tripping) that had the trip coils of all three poles wired in series. I checked the OEM drawings and this is how it came from the factory. I could not find the nameplate to verify trip...
It is well established that the North American / ANSI world favors dead tank HV Swgr and the IEC world favors live tank. With that said, I'm curious about the reasons or opinions for these differences. Excluding HV Metering CT/VT.
Consider a 362kV DT Breaker (SF6 Type)
Single Large...
I'm looking for either a ready made device or something simple for one of our test racks and a few other applications. The primary use would be powering logic (opto isolated) inputs on protection relays, PLC's and similar. Most of our SEL devices have a universal power supply input, so I'll...
We have a project coming up where the client is using the new SEL T-400 traveling wave relay. I've read a bit about it and am curious if anyone else has applied it or similar to Transmission Line Protection.
Our team is commissioning a large station with 20+ Sf6 breakers of 345 & 138 kV Ratings. Following the OEM and Client specifications, we first slow close and measure stroke and wipe with static measurements. Main Contact and time travel measurements are then made, using the OEM's supplied...
We took on a small project to help curtail a solar array. The available kW (360) of the solar array exceeds the export limit set by the utility, (150kW). The plant load varies between 50-250 kW. There are no batteries to dump excess energy to. There is an intertie relay with CT's that are at...
We are designing a relay upgrade for a client. I was reviewing existing and reference schematics and was looking for controls for functions like 79 and POTT (comm), which made me consider that this utility may be utilizing relay push buttons for these functions.
In our region, for whatever...
From time to time we test HV CCVT's (115kV-345kV). We have found that when using a TTR or similar, the measured ratio is nowhere near the calculated (5-15%). We have used TTR kits that claim to be able to accurately measure the ratio and have varied the voltage up to 100V on the primary.
What...
