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I deal with some really big motors. Primary heat transport pumps are 11,000 hp at 6.6kv with across the line starting and you have to start all 4 at the same time to prevent flow reversal in parts of the process.
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Dec 20, 2013 22:43
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| # ¿ May 21, 2024 01:47 |
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grover posted:
It can keep going without the grid but cant start. PHT pumps take more power than the standby generators can deliver. We need around 40 Mw to run up. Very few power plants can darkstart. I worked at a hydro plant that could, they had a battery box with jumper cables you could hook directly to the brushgear and a mechanical governor.
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Dec 22, 2013 03:23
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took a second before I remembered you work at a power plant. That's an insane amount of energy! I take it the plant isn't black start capable?
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You only need a handful that can darkstart to get the grid going again. That and it would be extremely rare to have a complete failure of the grid with all generators offline. Even in 2003 there were parts of the grid that islanded and were able to bootstrap the rest once they figured out what was wrong. This is where protection schemes need to be very well orchestrated.
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Dec 22, 2013 05:30
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Gisnep posted:We have a circuit that continuously monitors generator electrical output and compares it to the turbine steam inlet pressure. If it senses a significant mismatch between the two, it will automatically throttle the turbine inlet valves to prevent an overspeed. Power/load unbalance is quite the trip. We compare first stage pressure and output current. When the breaker opens a modern static exciter can respond pretty drat fast to keep terminal voltage steady. Opening the exciter contactor with any field on the generator can be really bad as the reverse voltage generated by the collapsing magnetic field can be very high so we have a deex and crowbar circuit. The sequence of events for our exciter is stop on running with the 52g open, stop bridges, then deex/crowbar to kill the field, and finally the exciter contactor opens.
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Feb 5, 2014 00:30
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Only a few small plants control frequency and the rest sync to that. Generator excitation plays a very important role in damping the low frequency oscillations between plants. From what I have heard the inductive reactance of a long line is enough that you cant just dump a generator on it without tripping. You have to energize smaller segments together before connecting a long line.
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Jan 7, 2015 02:41
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TheFargate posted:I dont know about other companies, but we dont really use copper anymore. Everything is aluminum now. No more copper bus, I cry a little every time we throw it out. We use tin plated copper bus bars. Tin whiskers have a very strange texture.
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Jun 30, 2015 15:38
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We have to watch out for frazil ice when things get really cold. Apparently massive icicles on the moving trash racks makes a hell of a noise.
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Oct 20, 2015 03:21
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It is interesting to see just how much energy you can get out before you hit the point where it is not worth while. The exhaust steam from the turbines where I work is so cold that you would be hard pressed to brew a cup of coffee with it. 25 C at 5 kPa absolute. Still has a shitload of energy in it though just not worth trying to extract more.
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Nov 11, 2016 17:53
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The condensers are enormous. Each turbine is rated at 875 mw so are still talking about a large amount of heat. We have a vey extensive feed water heating system. We pull extraction steam out of the turbine to control moisture levels and it is condensed to preheat feed water. The water hitting the boilers is around 125 C. In the winter we use extraction steam to heat the building. It hardly effects the units output at all. helno fucked around with this message at 04:25 on Nov 12, 2016 |
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Nov 12, 2016 04:22
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| # ¿ May 21, 2024 01:47 |
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Loopoo posted:Is this the right place to ask for help regarding Electrician stuff? Ie I'm looking to wire something up (a Nest Thermostat) in my apartment, and it'd be great if someone with electrical experience could help me in that regard. First tip. Return it and buy an Ecobee3.
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Nov 16, 2016 18:53
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