bhel vis

1. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 1 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL. NO
1.0
2.0
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LIST OF CONTENTS
PLANT DETAILS
OBJECTIVE
PROPOSAL
SERVICES REQUIRED
SAFETY PERECAUTIONS
EMERGENCY PROCEDURE
STATE OF THE PLANT
METHOD
COMPLETION CRITERIA
APPENDICES
A. TECHNICAL SPECIFICATIONS

2. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 2 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
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PLANT DETAILS
BHELVision – 20 System consists of a pressure vessel, with
electrodes mounted on it, Ascertor cabinet, local and remote
display units. An array of electrodes mounted on the pressure
vessel measures the resistance of water and steam. The
electrode outputs are processed in a compact electronics cabinet
viz., Ascertor. Water/Steam levels are indicated by a high bright
LED based local display mounted on the Ascertor cabinet.
Information is transmitted to the control room for driving the UCB
mounted remote display unit and optional display unit at fireman’s
door. Hence, the system consists of the following items.
Necessary mechanical hardware including a pressure vessel of
appropriate size with isolation and drain valves
Sufficient number of rugged flange type electrodes (typically 12
Nos.)
Ascertor cabinet mounted at drum floor with integral local display
PTFE cable between electrodes and the Ascertor cabinet
(Standard) 15 Metre length
Remote display unit for UCB
Remote display unit for fireman’s floor (optional)
Necessary cable from the Ascertor cabinet to remote display unit
at UCB and at fireman’s floor.
2 Nos. of pressure vessels fitted with electrodes. 2 Nos. of
BHELVISION – 20 Ascertor cabinets and 2 sets of remote level
indicators are supplied, to cover both sides of the drum
STATUS
Signatures
NTPC BHEL

3. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 3 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
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Employing the principle of measuring the different conductivities
of water and steam, BHELVISION – 20 offers a degree of
accuracy unmatched by conventional level indicators.
The Ascertor continuously monitors the system. The electrodes
are exicted by the AC source and the output signals are precision
rectified and compared with necessary threshold values. If the
signal is less than the lower threshold value, the output indicates
the presence of water. On the other hand, if the signal is higher,
than the upper threshold value, the output indicates the presence
of steam
BHELVISION – 20 incorporates several safety features. Notable
among these are:
• Separate electrical processing for each electrode to ensure
only single level loss on any component failure
• Firmware based validation circuitry to confirm the information
conveyed by the Ascertor is always true. Invalid sensing by
any electrodes (i.e. water above steam or steam below water)
is indicated by a fault lamp on the display. Only the valid
signals initiate the trip relays for high or low trip.
• Dual power supplies (one supplying odd channels and the
other even channels). Even if one power supply fails, the
other power supply automatically feeds the entire system,
thus ensuring availability of power supply all the time.
4 to 20 mA current output expounds the applicability of
BHELVISION – 20 both on indication and data acquisition for
trending and diagnostics.
STATUS
Signatures
NTPC BHEL

4. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 4 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
2.0
2.1
3.0
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OBJECTIVE
The objective of this procedure is to commission the
BHELVISION – 20 Drum Level Indicator and make it available for
Unit Operation.
PROPOSAL
It is proposed to commission this Drum Level Indicator and
compare its performance with respect to i) Direct water level
gauge and ii) Other remote water level Indicator of Drum
SERVICES REQUIRED
Communication and lighting facility at Drum Level and at Control
room.
Availability of boiler with drum filled and preferably, boiler in
steaming condition
Availability of a good working crew to attend to any electrode
leakages during commissioning
Availability of LT supply (AC & DC) (Refer Technical
Specification).
STATUS
Signatures
NTPC BHEL

5. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 5 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
5.0
5.1
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SAFETY PRECAUTIONS
While charging the level indicator, extreme precaution taken to
slowly charge the vessel and gradually warm up.
Control Panels erected at Drum Level are ensured for safety from
hot water / steam etc.
Control Cabling done between Pressure Vessel and Control
Panel at drum level are safely routed avoiding hot zones.
Extreme precaution taken while attending any leaking electrode.
Required isolation are made before attending any leakage.
EMERGENCY PRECAUTION
The test team should be aware of the lay-out of the
BHELVISION – 20 Drum Level Indicator, in order to react for any
emergency.
If there is any sudden electrode failure leading to heavy leakage
of water/steam, then extreme care to be taken to isolate the level
indicator by closing the isolating valves.
The test team should be aware of steps to be taken to meet any
emergency due to damage to any item / injury to personnel
STATUS
Signatures
NTPC BHEL

6. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 6 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
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STATE OF THE PLANT
Pressure vessel erected as per recommended drawing to the
correct limbs in the drum (Both RHS & LHS)
Electrode erection completed
Control Cabinet (Ascertor Unit) and the connected cabling
completed from drum level to control room
PTFE Cabling from electrodes to Ascertor Panel completed
Remote indicator in control room erected and ready for
commissioning
Operating floor indicator erected (This is optional)
Input power supply is made available
a. 1110 V AC, 220 V AC/DC
b. 24 V DC
(Single or Dual feeder)
Electrical checks completed and system ready for commissioning
STATUS
Signatures
NTPC BHEL

7. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 7 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
8.0
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METHOD
When the unit is under steaming condition, charge the pressure
vessel very slowly by opening the isolating valve in the water limb
first and then steam limb. Warm up the vessel sufficiently.
Observe for any leakage and attend
Slowly close the drain valve (kept open for warm up) and
pressurise the vessel to the unit working pressure
Observe for any leakage and attend
Charge the electrical system and switch on the circuits for
operation
Observe the level indicated by the level indicator and compare it
with direct level indicators / other drum level indicator
(Generally, this type of drum level indicators are more accurate
as it performs on conductivity and does not require any density
correction)
Both BHELVISION – 20 Drum Level Indicators are commissioned
as above and released for operation of the Unit.
STATUS
Signatures
NTPC BHEL

8. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 8 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
9.0
9.1
10.0
COMPLETION CRITERIA
With completion of activities as proposed in Section 3.0,
Commissioning of Drum Level Indicator is concluded.
APPENDICES
a. Technical Specification
1) Basic Equipment
Electrodes - Typically 12
PTFE Cables from - 15m standard length
Electrodes to ascertor
Ascertor Unit - IP55 enclosure, wall mountable with rain
canopy.
Remote Indicator - Hi-bright LED type indicator with green
colour for water, red colour for steam
and yellow for fault.
Local Indicator - Same as above, mounted on Ascertor
Unit.
Operator Floor Indicator - Optional.
STATUS
Signatures
NTPC BHEL

9. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 9 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
2) Pressure Vessel
Capable of withstanding upto - 207 bar
Steam / Water tapping distance - 635 mm for 12 probes
(other sizes on request)
Probe sight range - 550 mm (for 12 probes)
Steam/ water connections - 25 mm bore butt weld.
Made up of forged carbon steel, thick wall design.
No. of probes variable based on boiler drum size. (Standard is 12
probes)
3) Electrodes
Type of construction - Rugged Flange type with SS body,
fitanium tip and ceramic insulator.
Manufacturer - BHEL/EPD, Bangalore.
4) Electrical Specifications
Freely selectable alarm/trip - 25 to 275 mm (in steps of 50 mm
for high and low).
STATUS
Signatures
NTPC BHEL

10. Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0042
NTPC Ref no SIM/1/TS/1/42
Sheet 10 of 10
Plant area: BOILER
PROCEDURE FOR COMMISSIONING OF DRUM WATER LEVEL INDICATOR
SL.NO
Change over - 0.25A @ 220V AC.
Contact rating - 0.5A @ 125V AC.
- 1.00A @ 60V AC
- 2.00A @ 30V DC.
Current output - smooth 4 to 20 mA
Corresponding to water level.
Self checking
Firmware based validation
100% resolution even with one power supply fail condition.
Input power supply - 110V AC, 220V AC/DC 24V DC
(Single or Dual feeder). Any
combination can be ordered.
STATUS
Signatures
NTPC BHEL

11. PROCEDURE FOR COMMISSIONING OF
DRUM WATER LEVEL INDICATOR