The BBC is reporting widespread blackouts in London and the SE and I can see that a lot of emergency generation has started up (suggesting low frequency cut in). It'll be interesting to hear what happened and how low the frequency got. This is at least the 4th low frequency event so far this...
I've just had a look at one of our test certificates (400kV, class 0.2, 20VA unit) and there is a slight variation in accuracy (0.02% and 0.8min) when the burden of the other secondary is varied. That compares with a variation of 0.03% and 1 min between 25% and 100% burden for this VT. So the...
I look after high accuracy tariff metering systems so come across this problem regularly these days. I add a dummy burden in parallel to take the winding up to 25% burden. Where there are two secondaries I burden both up to 25% even when only one of them is used for tariff. Then you can use...
Was that a well known one in the UK Scotty? Remember that one well, we had to change all of our documentation to make sure that the difference between off load and off circuit was clear.
The worst one I heard of was a transformer that had an internal fault during energisation that caused the...
When I was fresh out of university I did a lot of careers evenings for the IEE (as it was called then) and a few sessions in schools. There was very little support from the older engineers (who felt they were too old to be able to relate to the kids) so I got slightly disillusioned and once I...
I would understnad that to mean that import active energy is input into the module (such as a motor or load centre) and export active energy is output from the module (from a generator).
It looks like an extension lead rather than fixed wiring to me so probably not covered by the wiring regs. I suspect there are plenty of violations that weren't mentioned/photographed though!
It's not my area of specialism but we switched from using Hydran to Calisto for our (European) GSUs due to on going maintenance costs. I was on the operational side when I was site based so don't know how easy or hard it was to intergrate into our SCADA network. We used to get a single value...
The under excitation probably came up due to a change in power factor which pushed the machine (further) in to the lead. This will have happened due to changes on the grid which you AVR responded to so it maintained GT terminal volts.
Under excitation does not mean low excitation, it means you...
I can't link to any photos but we had a 7MW set synchronise out of phase a few years ago, the stator winding and core were both damaged (there were flashovers between the winding and core) and the turbine/gearbox coupling bolts failed causing consequential damaged and a fire. Not pretty, the...
I had reason to look through a connection agreement for one of our DNO connected sites (132kV) and that needs to run in PF control mode. That partiular site is design to run in island mode in case of loss of connection to the main grid, so any site with blackstart capability will need to be...
As the others have said the AVR maintains the generator terminal voltage and generally has negliable effect on the grid volts (we consider it to be an infintie busbar). In theory the high grid volts could occur at any of the tap positions of the step up transformer.
I'm guessing you're UK...
Generally metering CTs are more accurate than protection CTs (especialy at the lower values of current) but saturate at much lower currents. I'm responsible for a good few tariff metering circuits (UK based) that range from around 5MVA to 700MVA and most of those use class 0.2s CTs, some of the...
Kenat - I'm on the bottom rung of management now and I can say with confidence that not just female engineers need encouragement and guidance!
Graybeach - I don't think females in my company are paid less than men (apart from pro-rataing for part timers). I don't know if this is more common in...
I'm not sure it will be much more palatable coming from a female engineer, at least that hasn't been my experience. I've been working in engineering for the last 18 years and have mainly kept clear of women only events as I don't agree with them. I've been asked why by some fairly senior...
