The discussion on "Handling of Turbines During Emergencies" has been detailed in the ppt. Some case studies are also discussed in the session where the course participants express their difficulties while coming across the emergencies in handling the turbines at their locations.

1. HANDLING OF TURBINE DURING
EMERGENCIES
MANOHAR TATWAWADI
Director, TOPS,
mtatwawadi@gmail.com

2. EMERGENCIES IN TURBINE AND
AUXILIARIES
Representative emergency operations
1) Partial load throw off (due to high frequency).
2) Partial load throw off due to Aux. Failure.
3) Sudden increase of load from full load
4) Vibration high
5) Differential Expansion high/low
6) Axial shift high
7) Loss of vacuum
8) High level in condenser
9) Loss of Barring gear or barring gear fails to start

3. Partial load throw off
(due to high frequency).
PROBABLE REASONS ACTION TO BE TAKEN
The steam pressure at ESV will increase FSSS operator will control the boiler
pressure. Governor will control the load. If
it fails, then throttle the control valves
suitably and maintain pressure to normal
till the frequency comes down
The turbine load will decrease There should be a constant watch on the
supervisory instruments. Disturbance in
differential expansion, vibration, axial
shift, eccentricity
Disturbance in condenser level Adjust and maintain the hot well level
Disturbance in vacuum Check and adjust ejector steam pressure
and gland steam pressure to normal
Turbine lub. oil temp will change Adjust coolers water flow as necessary
Disturbance in Deaerator pressure Deaerator pressure tends to fall, maintain
it through extraction or PRDS.

4. Partial load throw off
(due to Aux. Failure)
Probable Reasons and Action to be taken
There is a provision for initial load throw off by help of a
relay without time delay which reduces turbine load to
100 MW in case of tripping of following equipment’s
One C.W. pump in case both are running: If the partial
load relay fails / not in circuit reduce the turbine load
and inform the boiler operator to control steam
parameter in case one C.W. pump or one condensate
pump trip.
Careful watch may be kept on vacuum. Inform the local
operator to check the cause of tripping.
Maintain the deaerator and hotwell level.

5. Partial load throw off
(due to Aux. Failure)
• One BFP in case two are running and standby
does not come on auto remote /not available.
• One condensate pump in case two are running
and standby dose not come on auto/remote
not available
• And also due to tripping of any one of I.D. fan,
F.D. fan P.A.fan.
• In case of full load throw off (due to opening
generator breaker): Unit trip on protection

6. Partial Load Throw Off
• The turbine may trip due to over speeding :
Close the control gear hand wheel
• If closing control valve can control the speed :
Check that ESV and control valves are closed.
immediately otherwise
• Trip the Turbine by emergency trip button:
Close the valves in the M.S. line. Close the
Extr. steam valves.

7. Sudden increase of load from full load
• Probable Reasons and Action to be taken:-
• Low frequency : Since the turbine is on governor
control the load will increase due to fall in speed.
Reduce the load by the control gear and bring the
boiler parameter and load to normal.
• Due to sudden rise of boiler drum pressure.:
Bring back the load /governing wheel pressure to
normal by control gear and inform the boiler
operator.

8. Vibrations high
Probable Reasons and Actions to be taken
• Normally the vibration in bearings should be within 40
microns. If it exceeds the limit, turbine should be shut down.
• Check the turbine cylinder drain should not be cold (if
necessary open the drain valve for few minutes if turbine is on
load).
• Check bearing oil press flow and temp. to be normal .
• Check for any rubbing sound etc
• Turbine bearing oil press low : Reduce the load /speed. Check
the main line pressure and maintain it.
• Bearing oil inlet temp. High :Check the cooling water valves
are open in oil coolers and vent the coolers. Put the standby
cooler in service, ensure C.W.P. is running normal. Check
bearing oil outlet temp. (less then 65° c )

9. Differential Expansion high/low
• Probable Reasons and Action to be taken:-
• Normally the rotor gets long during running and gets
short during shut down. The expansion is to be
controlled by admitting steam or shutting off supply to
flange and stud heating, chamber heating accordingly.
In case if it goes beyond control, the machine to be
tripped:
• Check the steam temp. reduce load / speed. Check the
valve for flange heating is in open condition if rotor is
long or close if rotor is short.
• Check and adjust gland steam temp.
• Check the vacuum to be normal

10. Axial shift high
Probable Reasons and Action to be taken:-
• In case of excessive shift the turbine will trip through the protection
• Sudden change in load: Control the load and maintain the steam
parameter.
• Abrupt change of steam parameter: Control the load and maintain
the steam parameter
• Sudden closure of FCNRV of heater (HP/LP) : Control the load and
maintain the governing pressure, if heaters are healthy open
FCNRV.
• Variation in lub. Oil temp .pressure and quality : Maintain lub. Oil
pressure and temp. for quality get the oil tested from laboratory
and if necessary oil is to be changed.
• Difference of oil temp.: from thrust bearing front & rear outlet
should not be more than 3°c.