Control.com - Nerds in Control

We have 15mw Steam turbine of BHEL make and was running with all the parameters in control. Plant was stopped for preventive maintenance and Turbine front and Rear Bearings were inspected. The type of these bearings are of TILTING PAD type with five pads in each bearing. The bottom two pads have provision for connecting RTDs to monitor temparatures. During shut down nothing was replaced as all the components were healthy and found workable.

Hence after proper cleaning the same bearings were used.

The plant was started after shut down and we found that the temp of both front and rear bearing was raising steadily and crossed alarm point during rolloing itself. Hence before reaching full speed we tripped the machine. The bearings were again opened for inspection and found nothing problem in both bearings. However we planned to replace the front end bearing even though it was perfect. The rear side bearing was kept as it is and assembled back.

The machine was rolled and we found this time only rear brg temp went high and front was in normal condition. We had two measuring points of temp in both the brgs and we could find the spare RTD of Front was indicating 100deg C and Rear spare RTD was indicating 67 deg C. This means one RTD in each brg was showing high and one normal. Both the RTDs were perfect.

We are keeping the m/c running and I would like to know the phenomenon as other parameters including vibrations are well within the limits.

Regards,

M.Rangacharya

I think fitting of the RTDs is defective. These RTDs are not properly fitted, showing wrong values.

Hsve you changed oil? This appears to be an oil related problem, such as too heavy viscosity.