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Sunday, 25 August 2013

COMMISSIONING OF ESP IN ATHERMAL POWER PLANT.


Collecting and emitting Rapping System Commissioning :


Geared motors :


-      In case of emitting electrode rapping system confirm that heating elements are properly fixed.

-      Confirm glands are properly placed

-      Insulators are healthy, clean and rigid without crack.  

-      Confirm the mechanical clearance for each rapping system and decouple the motor.

-      Confirm the tightness of motor terminated cables, proper earthing, proper dressing of cables.

-      Megger the motor and record  the IR value. Measure the coil resistance and record. Confirm IR value is at least 1Mohm. Otherwise heat the motor and till the IR value is satisfactory.

-      Confirm the local push button station control supply terminal are properly done.

-      Energise the concerned module and locally bump and confirm direction.

-      If the direction is reverse, correct the direction.

-      Couple and take trial run as per duty cycle of the motor to study the proper hammering. If the hammering is in the centre of shock pad in case of  collecting rapping system for all the hammers and the hammer in the centre  of shock beam in case of emitting rapping, stop the rapping motors.

-      Clear for tack welding of all bolt and nuts of hammers etc.

-      Commission all the rapping motors of all fields as above.


Disconnecting switches
-      Ensure Insulators are healthy, clean and rigid
-      HV bus terminal and earth connections inside are tight.
-      Operation of moving blades with HV and HV and earth contact is smooth and proper.
-      Copper cable between moving arm and insulator head is properly connected. Each disconnecting switch is provided with a danger plate and two external earth connections to earth mat.
-      Doors are closed tightly
-      Interlocks provided at doors handles are working properly.
INSULATOR HOUSING 
-      Insulators are clean, healthy and rigid
-      Copper tubes are straight and not loose
-      Heating elements are properly fixed
-      Earthing is proper
-      Screw legs and nuts for placement of alignment jigs are welded
-      Doors are closed tightly
-      Interlocks are working properly
-      Each insulator housing is provided with a danger plate and two external earth connection to earth grid.
ELECTRICAL SYSTEM
High voltage transformer rectifier (HVR) with electronic controller (EC) :
The transformer rectifier supplies the power for particulate charging and collection. The basic function of EC is to feed the precipitator with maximum power input under constant current regulation. Whenever there is a flash between emitting and collecting electrodes, the EC will sense the flash over and quickly react by bringing the input voltage to zero an blocking it for a specific period.
After the ionized gases are cleared and the dielectric strength restored, the controller will  quickly restore the power to a preset value and raise it to the original non sparking level. The EC ensures adequate power input to the precipitator while reckoning the electrical disturbances within the precipitator. Regulated ac power  from EC  is fed to the  primary of the transformer precipitator, which is stepped up and rectified to give a full wave power output. The transformer-rectifier is mounted on roof of the precipitator which the EC  is located in an air conditioned control room.
Auxiliary control panel(ACP)
This is an LTMCC of modular construction with individual modules for supplying power to the following equipment.
-Hopper heaters for each field
-Support insulator heaters
-Shaft insulator heaters
-Collecting electrode rapping for each field.
-emitting electrode rapping motor for each field.
-Opaque monitor
Safety interlock: A interlock system is incorporated to prevent accidental contact with live parts of the precipitator and to enable energisation only when the EP is boxed up.
Disconnecting switch: each field is provided with one disconnecting switch for isolation of emitting system from the associated transformer. In the ON position the emitting system is connected to transformer and in OFF position the emitting system is grounded
     
An ESP wall casing insulated ,cabling up to roof and roof sheeting in place.
                Hopper insulated with plate type heater in place with electrical connection and JB.
                                          ESP cable tray routing from control room one side.
 ESP roof top along with HVR transformer , disconnecting switch , insulator housing with heaters,
mechanical interlocks on housing , Rapping mechanism , disconnecting switches etc on view.
          Rapping mechanism with gear and motor erection under progress between two pass.



ESP Concluded.

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COMMISSIONING OF ESP OF THERMAL POWER STATION - A SHORT DESCRIPTION

After successful air leakage Test insulation work of inner roof ,casing wall can be start

simultaneously . Once insulation of inner roof is over laying of outer roof and other

equipment installation ( like insulator housing , disconnecting switch , transformer ,

rapping mechanism with drives , insulator heaters and finally top structures and sheeting)

will start. However if roof sheeting works completed before start of inner roof installation

then insulation work can be done during rainy seasons.

Following erection checks /dimensional checks are carried out on ESP.

- Ensure the gap between Gas distribution screen and bottom of in let funnel of ESP is 100+10 mm .

-Ensure the gap between Gas distribution screen and bottom of in let funnel of ESP is 100+10 mm .

-Ensure the distance between roof beam and emitting frame top is 195+5  mm minimum .

-Ensure support insulator bottom tip to emitting electrode frame top is maintained  as per drawing.

-Ensure the central line of collecting  rapping drive shaft centre to shock bar centre 310+5mm. If not .  available maintain it with proper shims.

-Emitting electrode support screen tube edge to emitting frame top edge distance is maintained as per drawing.

-Distance between centre of emitting system suspension point to first hook with collecting electrode frames maintained as per drawing. 

-Emitting frames to collecting electrode distance maintained as per drawing.

-Deflection plate to Emitting electrode suspension screen tube dimension is maintained as per drawing.

-Confirm the suspension rod is centrally located with respect to support insulator.

-Confirm the shock pad and tumbling hammer face are in the same vertical plane. If necessary confirm the same with chalk test by running the collecting rapping of each field.

-Set rings are in position.

-Clearance between shock bar edge to shock bar  guide is (40mm) and shock bars are moving freely.

-Ensure shock bar guides and link rods are aligned properly.

-Clearance between collecting electrode and hopper deflection plate in the vertical plane as per drawing.

-Straightness of shock bar and guide to be ensured.

-The distance between emitting electrode and collecting electrode is as per drawing.

-The pitch distance of emitting electrode as per drawing.

-Randomly check the spring back of emitting electrode.

-Verticality of all collecting electrode at all level to be ensured, otherwise to be corrected.

-Ensure deflection plates and throttling plates are arrested by welding.

-Distribution screen manhole doors are locked in position.


RAPPING SYSTEM:

-Confirm collecting rapping geared motor, clutch and coupling alignment .

- A slight axial play of the rapper shaft is maintained.
-     With rapping shaft. Mark the direction of rotation of the rapping shaft outside. Even a short running of shaft in reverse direction will extensively damage the shock bar.
-    Check the pin wheel arrangement for proper erection and confirm proper transmission of torque from rapping shaft. A minimum axial play of 5 mm on either side of shaft insulator is maintained. Correctly mark the direction of rotation over the geared motor.
-     Confirm correct style of scavenging screws are installed concentrically around the shaft insulators.
-     Check the collecting rapping shaft and emitting electrode rapping shaft-sealing arrangement as per drawing.
-     Confirm proper alignment of plain bearing and set rings and proper seating of rapping shaft in the bearing.
-     Drain the old oil from the gear box and fill new oil into the gear box as per lubrication recommended up to the correct level marked.
-     Confirm all drive motors bearings are greased.
-    Check all motor bolts are properly tightened after alignment.





continued to next part on commissioning.

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