Master Fuel vs Turbine Trip 1

[veritas]

Hi

Could someone please:

1. Explain what is the difference between Master Fuel Trip and Turbine Trip?

2. In general which generator protection functions should trip the MTR Fuel Trip and which the Turbine?

Thanks.

 

[crshears]

Sorry, veritas, but I've never come across these terminologies before as being discretely different; anyone else?

[I have a vague idea of how they might be different, but it's better to remain silent and possibly be thought a fool than to speak and remove all doubt...]

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[ScottyUK]

Can't answer Q1 as I haven't seen those terms before - if you hadn't said they are different I would have assumed they are fairly interchangeable.

Q2 I would suggest is anything the generator isn't going to recover from, i.e. faults rather than overloads / thermal problems like stator overcurrent, NPS current trip, field overcurrent, etc. Anything which has made your generator hot enough to initiate a thermal trip would benefit from letting the machine spin to extract the heat.

 

[Parchie]

veritas,
On a one-on-one arrangement, when your turbo-generator trips, it also sends a trip signal to the MFT (Main Fuel Trip) to stop the boiler. Other control strategies only annunciate, warning operators to start shutdown procedures (if not automatically possible).

 

[crshears]

Now I'M the one getting confused...is the OP in regard to a gas turbine plant, a steam boiler and steam turbine plant, a combined-cycle plant, or...?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[veritas]

I am specifically interested in a steam turbine. Spoke to a power plant operator yesterday (steam turbine) and they definitely make a distinction between turbine trip and MTR fuel trip.

Turbine trip refers to the closing of the valves cutting off the steam supply. MTR fuel trip refers to the boiler and all associated systems being shut down such as the mills.

 

[crshears]

Ah! Back when I worked in a coal-fired power plant we called these boiler trips and turbine trips respectively. There was a nuanced difference between turbine trips and generator trips as well...

So if I recall correctly:

Boiler trips: water level/flow issues, combustion control issues, etc.; depending on circumstances turbine and generator trips might not be initiated, specifically in instances where boiler purging and re-ignition could be accomplished in a timely manner and power generation resumed without encountering turbine rotor/casing differential expansion issues.

Turbine trips: issues with the mechanical side of the turbo-generator, i.e. overspeed, loss of lube oil pressure, high vibration, loss of vacuum / high back pressure, circulating water pump trips due to high trash screen differential, etc., etc; in these circumstances since there was no electrical fault involved "sequential tripping" was invoked to ensure steam flow was collapsed by way of limits switches on the main and reheat emergency stop valves confirming these were shut before the unit ring bus breakers would be sent a trip impulse.

Generator trips: electrical issues like loss of excitation/synchronism, for example due to AVR trips; split-phase or differential protection operation; main unit or unit station service transformer gas [pressure wave] trip; and so forth. Breaker tripping was without intentional time delay in such circumstances, involving a degree of hoping for the best as far as turbine overspeed was concerned, in other words, the ESV's and RESV's had better work, because there's no alternate choice [and the usually worked quite well].

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[veritas]

crshears,

My knowledge of generator systems are nowhere near as comprehensive as yours. Thanks for the post.

My interest in this is purely from a generator protection point of view. Had a discussion with a colleague as to which gen protection functions should trip the turbine and which the boiler (MTR fuel).

Picked up quite a bit from this thread.

Thanks again.

 

[JRMEE]

Please also see IEEE Standard 502-1985 IEEE Guide for Protection, Interlocking, and Control of Fossil-Fueled Unit-Connected Steam Stations

 

[crshears]

Glad I could help, veritas.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]