Can anyone please advise where the lube oil heaters are located on a frame 6B machine? We have the supply breaker tripping and need to split the heater elements from the three phase supply to see if we have one or more bad elements, but I can only trace the supply cable to junction box 'E' on the end of the machine. then the wires disappear into a conduit out of the back of the junction box under the accessory compartment. Where they emerge I have no clue...

 

Davidmcc,

Typically, the immersion heaters used on GE-design heavy duty gas turbines are in large diameter pipes inserted into the L.O. Tank from the left side of the Accessory Base. (The L.O. Tank Level Gauge/switches, L.O. Coolers and L.O. Filters are typically located on the right side of the Acc. Base; the heaters and the sensing devices (temperature switches; T/Cs; etc.) are on the left side of the Acc. Base.)

The pipes the heaters are inserted into usually have explosion-proof junction boxes threaded on the outside through which the power leads pass through from steel conduit. The heaters, once disconnected, can be withdrawn through the explosion-proof junction boxes.

I'm speaking of the configurations usually supplied when Frame 6B turbines were built in the USA. Now that they are packaged in Belfort, France, some of the locations may (probably) have changed, but they are still most likely immersion type heaters (meaning they are inserted through tubes into the L.O. tank (reservoir)) and they should be accessible from outside the tank for service and replacement without draining the L.O. from the tank. (Again, the Belfort Bunch seem to have carte blanche to re-design anything they see fit to change. Even if it has been working fine for decades, if it wasn't conceived and designed in Belfort, France, then it's not correct in their opinion and needs to be changed. Sometimes repeatedly over the course of a very short period of time.) So, if you're fortunate enough to have one of the GE EPE (Energy Products-Europe) units, you'll have to search some more but they should still be accessible from the outside of the L.O. Tank (one would hope!). You may have to open a few junction box covers under the walkway to find them if you can't find them in the voluminous manuals provided by the Belfort Bunch (another "improvement" deemed necessary to make them worthy of Belfort effort).

Please write back to let us know where you find them!

 

Our three are on the right side of the oil tank. There is a TIL on these, talks about reconfiguring the wiring (delta vs Y) so that they do not generate too much heat. Excessive heat has crack the tube that separates the element from the oil. We had a leak and now run on two heaters.

 

Thanks CSA,

you're right, the lube oil heater 23QT-1 is accessible at low level on the side of the machine. The elements are in a tube with a junction box on the end with a large screw on cap. There are three elements, six terminals. I tried pulling them out but they only moved out by about 10mm, I'll have another go today. As the other contributor points out, ours are connected in delta but we should maybe reconnect them in star to reduce the heat and the possibility of tube cracking. We have a second tube which just has a cover and no JB so for colder climates maybe there is a second heater 23QT-2 which I've seen on some device listings.

What threw me was the round-about route the wires take from the termination box on the end of the machine, they exit the rear of the termination box in a large conduit, it runs under the floor of the accessory compartment, emerges out of the floor half way along the compartment in a large conduit, continues at low level to turbine end of accessory compartment, with smaller conduits branching off, it drops down passing under the shaft to emerge on side of machine externally where it runs back to the heater which is just around the corner from the termination box where it started it's journey.

I know the French have their own way of doing things, I worked at Michelin before and they even have there own temperature scale for the rubber curing, it's degrees michelin and the conversion factor to centigrade is a company secret.

The element resistance is around 40 ohms each so the elements seem ok but our problem is the low insulation resistance to earth, it measures 300k ohms at 500V but I think when the current builds up the resistance drops further causing over-current and the breaker to trip. The machine was off for two weeks and most likely there is condensation in the tube.

We noticed that with the heater off, the heat still builds up in the oil when the aux lube oil pump runs. We have two machines, on one the heater is working and the other it isn't. With no heater it took 3 hours to go from 21 deg C to 27 deg C and with the heater it took 1 hour 50 mins. Where is this heat coming from? just the pump head? Seems as though living without the heater for a while isn't such a big problem.

Will let you know how I get on extracting the heater.

Thanks a lot for your advice.

David

 

The heaters pull out from the opposite side of the machine from where the terminals are. The element loop is linked to a bung on the opposite side from where the terminals are and the bung won't pull through the tube.

 

Davidmcc,

Good to hear you have located the heaters. Sounds like a very circuitous route--and unnecessary cable length--for the immersion heaters. (It is noted that you didn't confirm if the Frame 6B is a European-packaged unit, or a US-packaged unit. I have horror stories about the placement of 26AA-1 on US-packaged Frame 5 and -6B units; so while dubious placement and routing isn't particular to European-made units it does seem to be more haphazard on Eurpoean-made units.)

Yes; the act of pumping the lube oil with the Auxiliary L.O. pump does indeed add heat to the lube oil. Depending on the ambient at the site, it might not be necessary to use the immersion heaters if the Auxiliary L.O. pump is run during extended periods of cooldown (ratchet). Or, the operators could be instructed to just put the Auxiliary L.O. pump MCC starter in HAND when the lube oil tank temperature drops below some predetermined value when the unit is not running.

Please let us know what you ultimately determine about your heater issue.

 

Hi CSA,

The machines are of 1997 build by European Gas Turbines. There is no earth (ground) fault at the terminals and the wiring is >500Mohm at 1000V so I have to assume that the live (hot) entering an element is making it's way to earth (ground) and I don't think that is repairable. As our heaters are still tripping the breaker we will get a new heater and maybe a spare. On the end with he element loops attached to a bung, there is some aux pipework preventing removal more than 300mm at that side. Is there any problem with breaking the link to the bung and pulling out the terminal side, which is clear. It just looks like someone went to some trouble ie. by linking the elements to a bung slightly larger than the tube inside diameter to stop you doing that, maybe for a good reason, maybe just to stop the terminals vibrating out and contacting the cap on the end of the tube. Anyway, would you have the GE part number for the heater tube element bundle?

Thanks,
David

 

Davidmcc,

As a former GE employee (I no longer work for GE) I don't have access to any of their drawing archive systems. And, I believe machines of that vintage are in an older, French archive which didn't have an English front end for years.

Unfortunately, I also believe the Service Manuals provided with units of that vintage were very user-unfriendly and it was extremely difficult to find drawings and part numbers in the multitude of binders. I could never find an "index" or table of contents that was useful for getting to a group of related drawings (such as for the L.O. Tank on what GE US would have called the Accessory Compartment, for example). I spent, literally, hours at one site just looking for the drawing and part numbers for the turbine compartment space heater--only to learn that the space heater provided on that unit was a one-off and hadn't been documented in the manual anywhere. (Typical of Belfort.)

Anyway, I can't help with a part number, and the best I can recommend is to contact your local GE Parts Edge representative (I think that's who sells parts for GE Frame 5s and 6Bs now) and give them your unit serial number and turn them loose on finding a part number. If they really want to sell you L.O. immersion heaters, they should be able to come up with a part number!

As for removal, I haven't a clue as to what's been done. Again, if you could find a drawing in the Service Manual perhaps you could see what was done, and maybe there might even be a Note on the drawing somewhere (though you might need to use an Internet language interpreter because it will likely be in French!) about installation/removal.

I wish I could be more help! But, as I said before, machines packaged by that division of GE are usually very "unique" to put it mildly. And the manuals are not very user-friendly (which is why I'm guessing you're asking for a part number).

Best of luck! Let us know how you fare!

 

Having a similiar lube oil heater issue with the heater cutting out after 30 for 40 secs. Sounds very much like this TIL may help. Although I understand it is GE proprietry info and cannot be copied to me, would someone be able to at least give me the TIL number and the possible date it was issued.

thanks
Topcat

 

Would like to try again with my request above. Can anyone help with this TIL regarding the lube oil heaters. As these heaters seem to be immersion type but are in a well of air rather than oil would they not therefore overheat and trip the thermostat. So would like to hear of a similar problem and its solution

thanks
Topcat