Commissioning
of Governing System of BFP Turbine
Check that the oil lines
from governing rack to governing elements and at the governing rack are as per
drawing with proper slope.
Ensure main and auxiliary
control valves lift reference indicator is fixed and set to zero position.
Check the damping valve
in HP and LP secondary oil lines are kept open by few turns.
Check the filter elements
at the control rack of the duplex filter are clean and healthy.
Ensure emergency stop
valve open / close limit switches mounted and wired.
Switch off the supply to
the following solenoids.
a) Trip solenoid valves,
b) Remote reset of trip lever solenoid valve.
c) Power supply off to the I/H convertors.
Ensure lube oil pump in
service and charge governing oil to the governing system.
Ensure all pressure
switches and pressure gauges in governing rack are charged and their drain
valves are closed.
Reset the turbine locally
and ensure following:
a) Trip oil pressure more than 5.0 kg/cm2.
b) Stop and control valves in closed condition.
c) HP and LP secondary oil pressures less than 1.0 kg/cm2
Ensure oil temperature of
45-50 deg C during governing system adjustment.
Opening / closing of
emergency stop valve.
Ensure power supply for
solenoids (It will be normally in deenergised condition)
Ensure no steam available
ahead of ESV and live steam isolating valve in closed condition.
Give open command to ESV
and observe the following sequential
operation of solenoid valves .
a) Both solenoids energises. Oil pressure above piston more
than 5 kg/cm2 and below disc 0 kg/cm2
b) Solenoid deenergises
oil pressure above piston more than 5 kg/cm2
and below disc more than 5 kg/cm2
.
c) Solenoid also deenergises. Oil from above piston starts
draining gradually through orifice and ESV opens.
d) When ESV full open oil pressure below disc is more than 5
kg/cm2 and above piston ‘0’ kg/cm2 .
Adjust open limit switch and check feed back available in control room.
By tripping turbine trip
lever, ensure tripping/closing of ESV. Check close feed back available in
control room.
Reset the turbine from
remote by energising corresponding solenoid
Ensure the same solenoid gets
automatically deenergised when trip oil pressure raises more than 4.5
kg/cm2 through pressure switch.
Switch on power supply to
HP and LP I/H convertors.
Give 4 mA current to HP
I/H convertor with external source or through governor panel.
Ensure HP sec. Oil
pressure of 1.5 kg/cm2. If not set the pressure to 1.5 kg/cm2 by adjusting potentiometer in I/H
convertor.
Check that the control
valve servomotor pilot is rotating freely and having a slight up and down
movements.
Check the main control
valve servomotor is just opened, by 0.2 mm. The start of opening can be
measured by fixing dial guage on servomotor.
If the start of opening
is not correct adjust the adjustment screw of the pilot slide to achieve the
start of opening.
Raise the current to I/H
conventor to 20 mA. Observe HP sec oil pressure increases to 4.5 kg/cm2 . If
not adjust the potentiometer of I/H convertor to achieve the pressure.
Check the main control
valve servomotor lift is maximum. If the lift is not correct adjust feed back
angle to obtain the full lift.
Check and adjust
auxiliary control valve servomotor similarly as done for main control valve .
Record control valve
characteristics (from 4 mA to 20 mA to I/H convertor)
1. Current mA Vs HP sec
oil pressure Vs main control valve lift.
2. Current to LP I/H convertor mA Vs LP sec-oil pressure Vs
Auxiliary control valve lift.
Compare the characteristics
and ensure these are in line with governing adjustment diagram/ shop floor test
protocol.
Operate the tester for
ESV and ensure partial closing of ESV and put back the tester in normal
position, ESV opens back to full open position.
Energise the remote trip
solenoid and ensure the following.
a) ESV closed.
b) Main control valve is closed
c) Auxiliary control valve is closed.
d) Trip oil pressure is zero.
continued - PART-IV
