s-ind-e-01-eng-eng-13-003 rev000 – pcb igbt driver board varnish coating

Technical Instruction PCB IGBT Driver Board Varnish Coating

Wind World (India) Ltd; Survey-33, Bhimpore, Daman. Phone : +91 260 2220628 Fax : +91 260 2220068

Document Details Compiled By / Date : Arnob Sarkar / 27.04.2013 Checked By / Date : Prasenjit Bhattacharya / 30.04.2013Approved By / Date : Central TSS Team / 30.04.2013

File Name : s-ind-e-01-eng-eng-13-003 Rev000 – PCB IGBT Driver Board Varnish Coating Revision No / Date : 000 / 30.04.2013

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Operation Key: H091 1. General: From various TSS report (-0476, 0599), it has been observed that most IGBT failures are caused by the malfunction of driver cards. Dust and salinity deposition in presence of moisture, creates an electrically conductive layer and malfunction in driver cards causing failure of IGBT. To prevent this issue, all AMTECH driver cards have been started varnish coating from January 2012. This protective layer prevents PCBs from weathering effects. This instruction gives guideline of performing the varnish coating on PCB IGBT Driver Board. 2. Scope of application: This activity is applicable for IGBT driver cards of all models of turbine. This activity has to be carried out every four year; where dust and moisture is likely to get deposited. If PCB IGBT driver board alterations / revision index no 1 is not mark; then carried out immediately. 3. Safety instructions:

CAUTION!!! • Follow the 5 safety rules for working in Electrical Power supplies • Isolate the incoming AC supply and discharge the live parts while doing work with PCB

controller • Follow “Safety instructions for work on and at the WEC”!

4. Required tools and materials: Quantity per WEC:-

S. No. Description (Tools) SAP Qty S. No. Description (Material) SAP Qty

1 Anti Static gloves 91519 1pair 1 varnish coating ELMO luft 1A FD ELANTAS® 92801 100

ml

2 Digital Multimeter 18270 1 2 varnish thinner ELANTAS® 92802 200ml

3 Single pole Tester 250V 11629 1 3 sticker PCB IGBT driver terminal cover 92862 110

4 Paint brush 10mm soft bristle - 3 4 plug 10p MSTB 2,5/10 ST 5,08 35553 12

5 Beaker glass 200ml - 2 5 plug 2p 250V 12A MSTB2,5/2-ST RM5,08 4631 12

6 Steel tray 300mm X 200mm - 1 6 plug 3p 250V 12A MSTB2,5/3-ST RM5,08 2888 12

7 Kraftwerk box 18098 1 7 optical waveguide plug HP HFBR-4531 33058 24

8 heater fan 230V/250W ENERCON V2 77188 2 8 Polyvinyl masking tape 15mm - 0.1m





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5. Identification of new component:

a

Varnish- (ELMO Luft 1A FD) THINNER-234 IGBT Gate-Emitter terminal sticker

Handling and usage • These are flammable hazardous compound. Keep away from fire and electric

spark region. • Wear nose mask while handling these compounds. • Wear hand gloves while handling as this can create skin irritation. • In case of eye contact, wash with fresh water for at least 10 minutes, holding

the eyelids apart and seek medical advice. • Store in cool chamber at 25°C. Shelf life is 12 months from date of packing. Disposal • This compound should not be allowed in drain and water source. • TDS & MSDS available in SAP in transaction mm03 under DMS attachment.

6. Working steps:

1. Remove the complete one set of PCB Driver cards from the Power Cabinets of one WEC and install another new set of PCB IGBT Driver which is varnish coated.

Verify the new Driver card is working and run the turbine.

2. Bring the removed PCB Driver Cards at a closed atmosphere or a room where the dust and moisture cannot effects the PCBs.

ATTENTION

• Cutoff the control and power supply and before working in Power Cabinet, wait till DC Link

voltage discharge to 0V.

• Wear Antistatic gloves while installing & removing Driver cards.

• Avoid touching Gate-Emitter terminal of IGBT.

• Fix copper short Link at Gate Emitter terminal till the time Driver card is removed from

IGBT terminal.





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3. Clean each PCB with air blower and soft bristle of 10mm paint brush to remove the loose dust and particles deposited over the PCB (Pic-1 and 2).

4. Put transparent poly-vinyl masking tape on PCB Serial

Number and PCB Built in Date stickers on each driver cards.

5. Wear rubber gloves on both hands and nose mask. Take

100ml of Thinner-234 in a 200ml beaker. Take a tray of 300mm X 200mm on a table. (Close the bottle mouth of Thinner Can with cover cap as thinner is volatile.)

6. Hold PCB on the tray and clean both side of each PCB

gently with thinner-234 by a 10mm paint brush. All traces of sticky dust, corrosion, oil, grease & salinity to wash off. (Pic-3)

7. Dry the PCB by hanging through a clip for approximately

30 minutes in a 50°C climate to evaporate the thinner completely.

8. Put white vinyl sticker (25mm X 16mm) on each Gate-

Emitter and temperature measurement point of PCB IGBT driver card from front and back side of the PCB (Pic-4). Ensure the sticker covers the metal contact area completely. (Do not forget this point)

9. To prevent varnish entering inside electrical contact, fix optical blind plug on the two Optical receiver plug for IGBT triggering. Fix a 10pin plug connector on 10p-plug housing on the PCB and 2 pin plugs on 2p-plug housing. Cover the VCE protection connector and 3pin plug on plug housing in AMTECH driver card.

10. To reduce viscosity and ease of application by a brush,

thinner need to be mixed with varnish. Take 40 ml of ELMO Luft 1A FD varnish on a 200ml beaker and 10 ml of thinner- 234 in another beaker then mix up both materials in a beaker to make a mixture of 4:1 “Varnish and thinner” ratio. (Close the bottle mouth of varnish & thinner as it will dry in air).

11. Hold the card tilted in horizontal surface of the tray and coat the front side of PCB area uniformly over the components, tracks and pins of THD and SMD components. Keep PCB horizontally and dry it in air for 30mins. Repeat the same process on back side of the PCB. (As shown in Pic-5).

12. For curing of varnish, arrange a local heating chamber

where 50-60°C can be maintained for 1.5-2hrs. For this

Pic-1

Pic-2

Pic-3

Pic-4

Pic-5





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purpose use two cabinet heater fans (SAP=77188) inside an enclosed box. It is necessary to check the temperature of chamber during every 15 minutes by using thermometer. (Refer Pic-6)

13. Ensure the PCB is completely dry and a uniform layer of 20micron produced over the PCB. Remove the terminal stickers, all optical plug, 2-pin and 10-pin connectors gently from each board.

14. Put a blank white sticker on PCB Driver card and write the date of Varnishing in DD/MM/YYYY format.

7. Finishing works:

1. Refit the coated PCB Driver cards on WEC and check the functioning of driver card. 2. Mention the activity in Station Logbook, Service report and SAP.

8. Index Marking and Documentation Note: 8.1 Alteration / Revision Index Marking:-

After completion of this activity, mark alteration / revision index number - 1 in each PCB IGBT driver board with permanent black marker. 8.2 Documentation:-

Beyond the operation key H091, the additional description “PCB IGBT Driver Varnish Coating” must be indicated / mentioned in the service report and SAP system.

This is a preventive activity and hence enter in SAP under activity type= OP01 as PM activity type as P02 (Unscheduled Maintenance).

Pic-6

s-ind-e-01-eng-eng-13-003 rev000 – pcb igbt driver board varnish coating

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