User:Ralegankarmukund

single phase cooling fan for power transformer Advantage of 1 ph. cooling fan over 3 ph. fan are 1) Control ckt is vary simple 2) Thermal over load relay not required. 3) Three phase contactor are also not required. 4) MCB 1 phase do the perpose of 2 & 3. 5) Thermal contact can operate 1 or 2 three phase contactor there controling 3 or 6 fan. 6) The most buitiful advantage is s/s helper can go through the ckt & attain cooling fan trouble. 7) Costing will be reduced by (3000+1000+500, contactor,over load relay & wiring) Rs4500/-per fan.Further 1ph fan are cheaper than 3ph fan. 8) Costing can be futher reduced by deliting second sourse of power supply & its alied ckt. fan indication in control room(for at least non grid s/s). 9) Conrol cubicle will cost about Rs60,000 to Rs80,000/- Where as cost of fan is about Rs2000 to Rs3000 ( Total is 16,000 or 24,000) COST OF PROCTION IS 2 TO 3 TIMES MORE THAN COST OF EQUIPMENT ExEmply Junior Member Join Date: Jan 2008 Posts: 22 cooling fans Do you know when, 1-phase motors(circuits) are used and when, 3-phase motor(circuits) are used ?. Why do you want to burn the T/F for a shake of few bucks, as already in MSEB transformers are always running close to overload ? ralegankarmukund Please go through the % loading of transformer in ABT metering. ExEmply You are right !, your suggestions are also right. But, what happens many times to save money we sacrifice many things. See, three phase cooling fans are provided for cooling of power transformer, considering radiator size & amount of oil, 1-ph fan won't provide sufficient volume of air for cooling as there are rating limitations for 1-ph circuit. Hence 3-ph fans are provided. If you use 1-ph fan instead of 3-ph fan, T/F won't cooled properly, and ultimately there will be cumulative heating of T/F and could burn finally. If you are talking about distribution Transformer, may be your suggestions are perfectly applicable. I am from transmission sector, I don't know what is mean by ABT, could you please explain or give any reference, so that I can update mayself. 23-02-2008, 10:31 PM ralegankarmukund ABT Metering- Avalibity Base Tarif. This scheme iscompleted by secure meters ltd.in MSETCL.In many s/s it is operative,Harsool(A'bad) is one of it.I am working there as s/s Incharge. Please do not ignore advatange at sr. no.6 (it is nothing but users friendly techn    6 25-02-2008, 05:23 AM ExEmply Hi~ Thanks for update. One more thing, I want to know, is there relationship between ABT & Power Transformer cooling ? I am not doubtfull about your scheme, I appreciate your idea. But as far as Power Transformer(not distribution T/F) is concern, we should be more cautious. Because the cost of cooling control circuit is very neglegible as compared to the cost of power tran 26-02-2008, 09:41 PM ralegankarmukund Report from ABT-Tr.loading 1)While going through this Tr. are loaded below 80%.Now check name plate of any tr.for its 80% of capacity you will find ONAN. 2)Cost of protection is alwyas compair to equipment to be protected.In this case Tr.is not equipment under protection.For tr.diff.ckt,ref,directional o/c,Buchloz,prv etc. are in protection cost. 3)In case of burnining of fan replacement fan is cheaper. 28-02-2008, 12:46 PM S. P. Vasekar My friend seems to be getting fed up with maintenance of T/R cooling system. 3 ph cooling fan system may also be simple enough to maintain. In maintenance practice the phrase “Stitch a time saves nine” fits very much. Instead of doing this unnecessarily we try to find out the solutions by modifying the scheme. Hence solutions may be Let us maintain the original system (if remains to be there at all) If it is very much detoriated replace it with same system i.e. 3 ph Train the engineer (not helper) to maintain the system Days are coming where no transformer shall be loaded more than 60% Hence work load on cooling system shall get reduced Once work load get reduced maintenance problems will also get reduced (provided it should be used at least intermi 08-03-2008, 10:20 PM ralegankarmukund One recent incident-132/33 kV s/s the 132kV breakar has air presure operating mechanism.It consistant of compresor with 2hp motor.The s/s is comm. in 1999-2000.In this month the HV breakar of only one Tr.in s/s was trip.Total supply fail.The breakar was trip due to low air presure (ABB make).The L.T.supply cable fail in s/s there by supply of compresor motor fail.Presure slowly fall & HV breakar trip at 03.05hr. in morning. Now assume that this motor is a single motor.Due to cable fail MCB is tripping.The on duty opertor can easily change the motor phase there by fall in presure will not occure & total 132kV failure is saved. Restoration of supply is at 9.30hr in morning.Because 33kV backfeding is required. 10-03-2008, 05:36 AM ExEmply Junior Member Join Date: Jan 2008 Posts: 22 132kV CB tripping..
 * 1) 4 21-02-2008, 06:26 AM

Dear friend, At first there shouldn't be tripping on low air pressure, for low air pressure, first stage is an alarm & if further drop in pressure there is tripping or lock-out of CB. May be first stage low air pressure alarm contact is directly connected to CB tripping, it is wrong, correct it immendiately. It is up to user to keep tripping or lock-out on low air pressure, but at certain low pressure, CB tripping or closing operation is not possible & CB undergoes lockout position. I don't think, 1-ph compressor motor might have avoided the tripping instead of 3-ph motors. But low air pressure alarm might have avoided the tri nrupalakolkar Junior Member Join Date: Mar 2008 Location: Baroda Posts: 4 Transformer Cooling - Need-Invention & Maintainence
 * 1) 11 23-03-2008, 12:53 PM

Dear Sir, The concept of transformer cooling by ONAF using single phase fan instead of 3 phase was nicely explained. I appreciate the point no. 6 demonstrating that even the men of crade of apprentice trainee - electrician can attain it and all... But here we forgot 1 thing... single phase fan design, size limitations and cooling requirement assesment. In case of power transformers the amount of cooling air and the velocity of air i.e. Force and Speed both are important and therefore primarily a 3 phase circuitry is chosen as the 1 phase fan for same condition will require larger blade and surface compared to 3 phase... ! Secondly, if 3 phase system is chosen, phase wise load balancing required for sub-station auxiliary supply is also taken care of. The design recommendation for a cooling system need be re read for understanding the minimum requirements to be met by it. But in case of small radiator, low capacity transformers - distribution trafos.. one may go for this option... but again how many of these ones are really ONAF type? It is also well said if u spend penny you are bound to get nuts... Please comment. Nrupal nrupalakolkar Junior Member Join Date: Mar 2008 Location: Baroda Posts: 4
 * 1) 12 23-03-2008, 01:12 PM

In this incident narrated by you, the 132 KV breaker had tripped due to air pressure low low trip... where was air pressure low low alarm...? what was the shift staff doing in its routine checks to the switchyard & sub-station auxiliaries - which at many locations is once every shift and a compulsory round of checks in B i.e. second shift to be done? Why due to the tripping of the transformer the total sub-station supply failed? Come on lets resolve this... its important to understand the details. How would a single phase supply have possibly avoided the transformer breaker failure? If the L.T. Supply cable failed, why the auxiliary feeder failure alarm did not operate? Why was there no arrangement of aux- fdr alarm? May be I am asking details which need a detailed system description. If interested to proceed discussing on it please provide details... may be I may be of help! PDCA, FMEA and other tools based analysis for system failsafe can be achieved. Nrupal ralegankarmukund Senior Member Join Date: Feb 2008 Location: CIDCO,N-1 Posts: 121
 * 1) 13 28-03-2008, 10:26 PM

single phase fan are bulky no dout.But can you say ,elephant is get loaded due to man sittining on him.Please see that that wt. of power tr.is in few ton. 1 ph can also be designed as per requirment.Please ignore the loadining of station tr.& if not accpted to you then consult to anybody workining in distribution co.to whom you know. ralegankarmukund crack Junior Member Join Date: Apr 2008 Posts: 4 disadvatages of 1 ph over 3 Ph
 * 1) 14 07-04-2008, 04:04 PM

DisAdvantage of 1 ph. cooling fan over 3 ph. fan are 1. Load imbalance of s/s transformer is very high due to more loading of either phases of transformer. 2. Start of large power consuming 1 ph fans can draw large amount of starting current may cause large volage fluctuation in that phase. which may affect s/s taransformer and other equipment of that ph. 3. 3 ph fans are more reliable and of long life than 1 ph fans. 4. For same power rating fan, 1 ph fans will draw large current than 3 ph fans so cable ,contactor etc equipment have to be more capacity. cable has to be used bulky. 5. In 3 ph fans change in phase sequence and absence of any phase is esily observed though it happens rarely. 6. in design, use of 3 ph fan is due to more power consuption and balancing of load, which is not achived in single phasing. Originally Posted by ralegankarmukund Advantage of 1 ph. cooling fan over 3 ph. fan are 1) Control ckt is vary simple 2) Thermal over load relay not required. 3) Three phase contactor are also not required. 4) MCB 1 phase do the perpose of 2 & 3. 5) Thermal contact can operate 1 or 2 three phase contactor there controling 3 or 6 fan. 6) The most buitiful advantage is s/s helper can go through the ckt & attain cooling fan trouble. 7) Costing will be reduced by (3000+1000+500, contactor,over load relay & wiring) Rs4500/-per fan.Further 1ph fan are cheaper than 3ph fan. 8) Costing can be futher reduced by deliting second sourse of power supply & its alied ckt. fan indication in control room(for at least non grid s/s). 9) Conrol cubicle will cost about Rs60,000 to Rs80,000/- Where as cost of fan is about Rs2000 to Rs3000 ( Total is 16,000 or 24,000) COST OF PROCTION IS 2 TO 3 TIMES MORE THAN COST OF EQUIPMENT crack ralegankarmukund Senior Member Join Date: Feb 2008 Location: CIDCO,N-1 Posts: 121
 * 1) 15 26-11-2009, 12:28 AM

Quote: Originally Posted by crack DisAdvantage of 1 ph. cooling fan over 3 ph. fan are 1. Load imbalance of s/s transformer is very high due to more loading of either phases of transformer. 2. Start of large power consuming 1 ph fans can draw large amount of starting current may cause large volage fluctuation in that phase. which may affect s/s taransformer and other equipment of that ph. 3. 3 ph fans are more reliable and of long life than 1 ph fans. 4. For same power rating fan, 1 ph fans will draw large current than 3 ph fans so cable ,contactor etc equipment have to be more capacity. cable has to be used bulky. 5. In 3 ph fans change in phase sequence and absence of any phase is esily observed though it happens rarely. 6. in design, use of 3 ph fan is due to more power consuption and balancing of load, which is not achived in single phasing. 1.Load inbalace-- The cooling fan are of rating 340 - 680 wat i.e.0.5 to 1 amp in each phase.If 1ph fan is used then 1.7 - 3.4 amp.Generly 8 fan are used out of this 6 are in use & 2 are stand by.Thus 6 fan can be equaly be divided in 3 phase. 2.Can be esily ignored. 3. 1ph fan are reliable as they donot require single phase preventer. 4.cover under sr.no.1 5.It hapens very comnly. 6.Rating of fans is so small hens ignore. ralegankarmukund Posts: 121
 * 1) 16 25-02-2010, 08:09 AM

132/33/11 kV Jalna (oid) s/s 132/33kV 50MVA BBL make Tr.was comm in Jully09.Here also two sourses of 440V were consider.The supply change over is done with time dely rely (TDR). One of this relay is not workining giving unecesary indication in control room. 1) Actualy there is no need of two supply arrangement. 2) And hence TDR 3) Allied ckt of TDR ralegankarmukund