We have a problem of the grid CB opening as the flame goes off on shutdown of the GT. What could be responsible for this?

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Gmndarake... this is the classic problem, i.e., "Which came first, the chicken or the egg?"

So, did the grid CB open first, or did flame-out occur first?

 

> So, did the grid CB open first, or did flame-out occur first?

Phil.... the flame goes off first then the grid CB opens. The GT shutdown command has been issued and idles for 5mins before shutting down. It is immediately the flame goes out that the grid CB opens.

 

Maybe someone set it up that way on purpose.

--
Bob

 

> Maybe someone set it up that way on purpose.

Isn't the better question: Does the unit usually operate like this or is this a problem?

If this is a problem, when did this problem start?

What alarms are being annunciated during this five minute "idle" period if this is a relatively new problem?

Fuel is required to make torque. Torque is used to make amps. No fuel; no amps. There is a short period (milliseconds) between the time flame is lost and reverse power would be detected, depending on the power being produced when flame was lost so the two wouldn't necessarily be simultaneous.

I don't personally have any experience with smaller units like this, and my experience is pretty limited to Speedtronic controls and I don't think Speedtronic controls were used on these machines very frequently. So I can't be of much more help.

I just don't know if this is a problem, or just a question about why the breaker opens on loss of flame. Sorry; just don't have experience with these machines.

 

> Maybe someone set it up that way on purpose.

@ Bob,...NO,I don't agree someone set it so on purpose as this isn't the case if the GT aux are fed from the common coupler as against its own unit trafo.