WHAT IS DIFFERENCE BETWEEN POWER TRANSFORMER AND DISTRIBUTION TRANSFORMER

Power transformers are used for transmission as a step up devices so that the I2r loss can be minimized for a given power flow. These transformers are designed to utilize the core to maximum and will operate very much near to the knee point of B-H curve (slightly above the knee point value).This brings down the mass of the core enormously.

Naturally these transformers have the matched iron losses and copper losses at peak load (i.e. the maximum efficiency point where both the losses match).

Distribution transformers obviously cannot be designed like this. Hence the all-day-efficiency comes into picture while designing it. It depends on the typical load cycle for which it has to supply. Definitely Core design will be done to take care of peak load and as well as all-day-efficiency. It is a bargain between these two points.

Power transformer generally operated at full load. Hence, it is designed such that copper losses are minimal. However, a distribution transformer is always online and operated at loads less than full load for most of time. Hence, it is designed such that core losses are minimal.

In Power Transformer the flux density is higher than the distribution transformer.

Maximum Efficiency

The main difference between power and distribution transformer is distribution transformer is designed for maximum efficiency at 60% to 70% load as normally doesn’t operate at full load all the time. Its load depends on distribution demand. Whereas power transformer is designed for maximum efficiency at 100% load as it always runs at 100% load being near to generating station.

Distribution Transformer is used at the distribution level where voltages tend to be lower .The secondary voltage is almost always the voltage delivered to the end consumer. Because of voltage drop limitations, it is usually not possible to deliver that secondary voltage over great distances.

As a result, most distribution systems tend to involve many ‘clusters’ of loads fed from distribution transformers, and this in turn means that the thermal rating of distribution transformers doesn’t have to be very high to support the loads that they have to serve.

HOW WE GENERATE ELECTRICITY

HOW WE GENERATE ELECTRICITY 

In today’s world, we cannot think of any activity without electricity. Electricity has become an integral part of our lives .From small house hold purposes to heavy industrial works, everywhere we need electricity.

Where this electricity does comes from?

There are various power projects, Thermal power projects, Nuclear power project, Hydle power project etc. But the purpose remains same, that is generation of electricity and that too at same frequency for a particular country .A power plant converts one form of energy into another form of energy and to finally obtain electrical energy. In thermal, hydle and nuclear power project, heat, hydraulic and nuclear energies respectively are finally converted into electrical energy.

2.SOURCES OF ENERGY

1)  The Sun:-

The radiated heat energy by the sun can be utilized by generation of electrical power.

2)  The wind:-

The wind produced by the sun gets sufficient energy which can be utilized.

3)  Terrestrial heat or geothermal energy:-

During volcanic action, the material that comes out from the bowls of earth to form the volcanic explosion also produces the steam vents and hot spring.

4)  Ocean tides and waves:-

There is a tremendous energy in ocean tides and waves. At the time of hide tide, the gates are opened and water is stored in the tidal basin which can be used in generation.

5)  Water:-

Water at a high pressure or flowing with a velocity can be used to run turbine.

  6)  Fuels:-

   The main source of energy which may be solid, liquid or gas such as coal, oil or coal gas.

  7) Nuclear energy:-The tremendous amount of heat energy is librated by fusion of disintegration                 which can be utilized due to large amount of heat produced.

WHAT IS DIFFERENCE BETWEEN NEUTRAL AND EARTH WIRE IN HOUSE WIRING

WHAT IS DIFFERENCE BETWEEN NEUTRAL AND EARTH WIRE IN HOUSE WIRING- one phase and one neutral  wire are used usually across all appliances to give electrical supply to that appliance. But one earth wire is also laid which is used to connect appliance body earthed. To protect consumer, in case phase wire accidently got touched to appliance’s body  it can give shock to consumer. So to protect consumer, appliance’s  earthed body though earth wire protect consumer because phase current got route though earth wire and so current does not pass though consumer body. In electrical plug of three point most  upper one point is used to connect appliance’s body to earth wire to protect consumer.

HOW TO RECOGNIZE WHICH CONDUCTOR STAND FOR NEUTRAL

MAKING OF L. T. LINE-

In this world when we go to anywhere then we see alots of line and conductor at upside of our head. Then we confuse over which line stand for what?

L T line comprises 4 conductor systems three conductors used for R Y B phase and fourth one used for neutral.

How we recognize which conductor is for neutral- How we recognize which conductor is for neutral in four conductor( three for phase and fourth one for neutral) system.

1-      Neutral wire always laid at lowest in all four conductor.

2-      Neutral conductor is weakest in size.

3-      Neutral conductors are generally made of GI wire

4-      Neutral conductor is generally grounded at each third pole.

what is difference between HT and L T line

what is difference between HT and L T line -Tension word has been derived from French dictionary which stand for Voltage. A low-tension line is a low voltage line and a high-tension line is a high voltage line. In India LT supply is of 400 Volts for three-phase connection and 230 Volts for single-phase connection. High tension or HT supply is applicable for bulk power purchasers who need 11 kilo-Volts or above. Most small consumers of electricity like individual houses, shops, small offices and smaller manufacturing units get their electricity on LT connection. HT is applicable for bulk purchasers of electricity like industries (big manufacturing units), big offices, Universities, hostels and even residential colonies (if the apartment complexes purchase together in bulk). The tariff structures of most state distribution companies are different for LT and HT.

EXTRA HIGH TENSION LINE- line having Voltage of 132 kv, 220 kv and 440 kv also called extra high tension line.

HOW TO RECOGNIZE WHETHER LINE IS L T OR H T- in distribution system l t line possess 4 wire system- 3 for phase and 4 th one for neutral. and H T line don't has neutral wire. it only possess 3 wire for phase. 

                                                              L T LINE DIAGRAM                                                        

           

H T LINE DIAGRAM

 L T LINE WITH 5 WIRE SYSTEM- L.T. LINE contain voltage generally 220 v and 440 v. and in distribution system having  5 wire system. 3 for phase 4th wire stand for neutral and the 5 and last conductor usually placed for street light. but basically street light line got charged by any phase wire through looping.                                                                                                                                                                                                                                                                                                                                                                      

DIRECT OR KATIYA CONNECTION IN DISTRIBUTION SYSTEM

DIRECT OR KATIYA CONNECTION IN DISTRIBUTION SYSTEM- what is katiya connection in distribution system-katiya or katia connection-katiya connection means if someone put two wire one on  phase wire and other on neutral wire.of the  nearest L T line of distribution system to use illegal  electric connection then this system called katiya connection in distribution system.
I Think in india 50% connection are katia connection. in this connection people donot use legal connection and donot pay bill against its use.

WHAT IS ELECTRICAL METER TAMPERING

WHAT IS ELECTRICAL METER TAMPERING-When any consumer put shunt resistance across   C T terminal to bypass current which is to be measured called meter tampering. this video shows with diagram and real clip to make clear concept.Meter tampering means doing anything that causes the meter to run slower or not at all. It also includes anything that is used to divert electricity around the electric meter. Meter tampering is theft of electricity from the power company. Electricity meter tampering comes in many shapes and sizes.

Probably one of the most common ways that I have personally seen electric meter tampering has been to turn the watthour meter upside down. The question is does this work? Yes and no. It depends on what type of watthour meter your system has. One may think that since you do not have digital meters that turning the meter upside down will always make the meter turn backwards. However, there were some high security meters that had registers that would measure the consumption in the correct direction regardless of whether the watthour meter was upside down or right side up.

Most digital watthour meters now have a built in detent so that it actually does not matter. They will still register correctly. But they can alert us to meter tampering. Also, electromechanical watthour meters that have AMR modules only count pulses. So, it does not matter if the disc is turning forward or backwards the ERT will still register correctly.

The second most common thing that I have seen when people steal power is when they pull the meter out and put something in its place. I have seen people put in kitchen knives, copper wire, jumper cables and basically anything metal to save money by stealing power.

Next, people will try to steal power by tampering with the meter itself. They will drill a hole in the meter cover and insert something in it to stop the disc. This works because most of the time it is undetectable because the customer will only do it at night. So long as they remember to take it out during the day the utility has a hard time detecting that the customer is stealing power.

 TYPES OF CONDUCTOR IN DISTRIBUTION SYSTEM-In distribution system conductor used usually named by animal. like dog conductor, weasel conductor etc.

The animal names are a short-cut way of describing various standardized overhead power distribution lines, as typically used by utilities.

It is used in only a few countries and has as usual no scientific or  any other background. It is like rather than calling the material AISI  304L or BS304S12 (better)as 1.4306 call it penguin.

But then people do get some ideas and Someone likely would try to justify by saying that these are meant for linemen who won't be able to remember the numbers but if you look at the list then you would realize that for him to remember the names, he would have to be an expert in  lifesciences. 
Its pretty much like naming hurricanes like Katrina! :D

Further they are not standardized and vary from country to country. in india and asian country conductor used and their current capacity and it's cross sectionalarea are as below-

basically in distribution system weasel, dog, and panther conductors are used.as per requirement of load in amp.

TYPES AND CALCULATION OF CURRENT RATING OF DISTRIBUTION TRANSFORMER

RATING OF DISTRIBUTION TRANSFORMER WITH CURRENT RATING-
In distribution system there are basically 3 types of transformers(t/f)

1-low rating transformer
2- medium rating transformer
3-high rating transformer

low rating t/f contain -10 kva, 25 kva, 63 kva, 100 kva,

medium level t/f-250 kva 400 kva 630 kva

high rating t/f- 1 mva , 5 mva ,10 mva

all above distribution t/f are used on voltage-11 kv /440 v

and its current rating on lt side(440 v side) can be found  by 1.31* t/f rating= current rating

ex- current rating of 250 t/f- 1.31*250=325 amp

hence rating of t/f on l t side is 325 amp.

similarly rating on 11 kv side can be calculated by =current on l t side/25

ex-- for 250 kva transformer=325/25=13 amp.

CALCULATION OF CURRENT RATING of XLPE CABLE

Calculation of current rating of  XLPE cable- cable used in distribution system- In distribution system rating of cable  has been  decided by cross-sectional   area. hence for use of current we have to asked for cable on its cross-sectional area. Hence for 11 kv line in distribution system following types of  the cable are used.-

72 mm2 xlpe cable = current rating= 93 amp

120 mm2 xlpe cable= current rating=156 amp            

185 mm2 xlpe cable= current rating=240 amp

240 mm2  xlpe cable= current rating=240*1.3=312 amp

300 mm2 xlpe cable= current rating=300*1.3=390 amp

Appox Current rating of cable from its cross sectional area rating can be calculated by by following formula- cross sectional area* 1.3

Hence formula would be- cross sectional area*1.3= current rating

Example- 120 mm2 XLPE CABLE current rating would be- 120*1.3=156 amp.

Difference between PVC cable and XLPE cable-PVC-Poly Vinyl Chloride & XLPE-Cross Link Poly Ethylene are 

the insulations used on the cables

PVC is thin insulation mainly used in LT side cables

XLPE is thick insulation used in HT cables

(OperatingTemp)(SC Temp) (MoistureRes)(Fire Res)

PVC 70 130 V.Good Excellent

HOW TO STEAL ELECTRICITY

HOW TO STEAL ELECTRICITY.

THERE ARE TWO METHOD ARE DESCRIBED.

BY STORING UNIT

IF WE SPENT 100 UNIT PER MONTH

AND  MAKE AND PAY  BILL OF ONLY 50 UNIT

AND WE STORE 50 UNIT SOMEHOW

THEN WE WILL PAY= 50*5=250 RS.

AND REST OF THE 50 UNIT GOT STORE

IF WE DO THE SAME CONCEPT ON EACH MONTH

THE WE STORE=50*12=600 UNIT

HENCE THEFT OF 600*5=30000 RS IN YEAR.

AFTER ,METER READING STORED UPTO HANDSOME AMOUNT THEN WE REPLACE THE METER.

 BY FIXED UNIT  THEFT

NA, NR, RDF, IDF  (DAMAGE METER DELIBERATELY)  BILLING-

IN THIS CASE IF METER IS NOT WORKING

ON 1KW  CONSUMER HAVE TO PAY FIXED UNIT PER KW ( SAY 50 UNIT) PER MONTH

2 KW CONSUMER HAVE TO PAY 100 UNIT PER MONTH

AND SO ON

IF  CONSUMER USE HEAVY LOAD  THEN HE DELIBERATELY DAMAGE METER

AND REDUCED THE SANCTION LAOD SO THAT FIXED UNIT WOULD BE PAID.

SO FOR 1 KW CONSUMER  WOULD PAY 50 UNIT. BUT ACTUALLY HE CAN USE AS 

MUCH AS MUCH 1000 UNIT PER MONTH

DISTRIBUTION TRASFORMERS PROTECTION

DISTRIBUTION TRASFORMERS PROTECTION-There are basically following rating  transformer comes under  distribution.

10kva, 63kva, 100kva,160kva, 250kva, 400kva, 630kva, 1000 kva.

 For all larger rated and important distribution transformers, over current protection along with restricted earth fault protection is applied. Differential protection should be provided in the transformers rated above 5 MVA(power transformer).

For distribution transformer in most of the times fuse system is used.

And copper strands are used in fuse. It’s cross section vary according to rating of transformers.

Step to follow save distribution transformer (D T) are as follow-

1-    Natural of  DT should be earthed  properly with low resistance wire.

2-    L T’s circuit should not be  short circuited (means phase to phase short circuiting)

3-    Oil level should be upto L T bushing

4-    Fuse at L T side and H T side be as per rating of transformer

5-    Current ( load)  should be not beyond  80% of  its rating.

Nature of Transformer Faults

Although an electrical power transformer is a static device, but internal stresses arising from abnormal system conditions, must be taken into consideration. A transformer generally suffers from following types of transformer fault-

1.     Over current due to overloads and external short circuits,

2.     Terminal faults

3.     Winding faults

4.     Incipient faults

All the above mentioned transformer faults cause mechanical and thermal stresses inside the transformer winding and its connecting terminals. Thermal stresses lead to overheating which ultimately affect the insulation system of transformer. Deterioration of insulation leads to winding faults. Some time failure of transformer cooling system, leads to overheating of transformer. So the transformer protection schemes are very much required. The short circuit current of an electrical transformer is normally limited by its reactance and for low reactance, the value of short circuit current may be excessively high.-There are basically following rating  transformer comes under  distribution.

10kva, 63kva, 100kva,160kva, 250kva, 400kva, 630kva, 1000 kva.

 For all larger rated and important distribution transformers, over current protection 

along with restricted earth fault protection is applied. Differential protection should be 

provided in the transformers rated above 5 MVA(power transformer).

For distribution transformer in most of the times fuse system is used.

And copper strands are used in fuse. It’s cross section vary according to rating of 

transformers.

Step to follow save distribution transformer (D T) are as follow-

1-    

Natural of  DT should be earthed  properly with low resistance wire.

2-    

L T’s circuit should not be  short circuited (means phase to phase short circuiting)

3-    Oil level should be upto L T bushing

4-    Fuse at L T side and H T side be as per rating of transformer

5-    Current ( load)  should be not beyond  80% of  its rating.

Nature of Transformer Faults

Although an electrical power transformer is a static device, but internal stresses arising from abnormal system conditions, must be taken into consideration. A transformer generally suffers from following types of transformer fault-

1.     Over current due to overloads and external short circuits,

2.     Terminal faults

3.     Winding faults

4.     Incipient faults

All the above mentioned transformer faults cause mechanical and thermal stresses inside the transformer winding and its connecting terminals. Thermal stresses lead to overheating which ultimately affect the insulation system of transformer. Deterioration of insulation leads to winding faults. Some time failure of transformer cooling system, leads to overheating of transformer. So the transformer protection schemes are very much required. The short circuit current of an electrical transformer is normally limited by its reactance and for low reactance, the value of short circuit current may be excessively high.

TYPES OF SUPPLY IN DISTRIBUTION SYSTEM

Type of connection  supply in distribution system  (LMV stand for low and medium voltage connection)

LMV-1 for light fan domestic connection

Lmv-2 for light fan commercial connection

Lmv-3 forr street light connection

Lmv-4 for govt. institution connection

Lmv-5 for govt. and private tubewel connection

Lmv-6 for industrial power connection

Lmv-7 for govt jal sansthan(water utility)

Lmv-9 for temporary connection

Lmv-10 for departmental connection

Hv-1 heavy connection heavy load greater than 100 kw(light and fan connection)

Hv-2 for connection having load greater 100 kw ( power)

Hv-3 for traction connection

HOW TO CALCULATE ELECTRICITY BILL

HOW TO CALCULATE ELECTRICITY BILL

 (FOR DOMESTIC USAGE 2 KW CONNECTION)

EXAMPLE -

CURRENT READING        PREVIOUS READING        CONSUMPTION (IN ONE MONTH)   

01-01-2017                               01-02-2017                   

150 KWH                                 100 KWH                             50 KWH (50 UNIT)

ELECTRICITY CHARCHES  (RATE PER UNIT @5 Rs )=       50*5=250  Rs.

FIX CHARGE (BASED ON LOAD) =50 Rs PER KW=50*2 =100 Rs

TOTAL CHARGES= EC+FC=250+100= 350 Rs.

TAX(ELECTRICITY DUTY)=  @ 5% OF TOTAL CHARGES= 5% OF 350=17.5 Rs.

GRAND TOTAL=350+17.5= 367.5 Rs.

IF ARREAR ANY OF PREVIOUS MONTH

TOTAL ELECTRICITY CHARGES = ARREAR + SURCHARGE ON ARREAR(2 % PER 

MONTH)+ GRAND TOTAL.