What is the Difference Between Power and Distribution Transformer
Content
what is the difference between power and distribution transformer?
Transformers are classified as two categories: power transformers and distribution transformers. Power transformers are used in transmission network of higher voltages, deployed for step-up and step down transformer application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) Distribution transformers are used for lower voltage distribution networks as a means to end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V)the main difference between power and distribution transformer is, distribution transf. is designed for max. efficiency at 60% to 70% load as normally doesnt operate at full load all the time. Its load depends on distribution demand. Where as power transf. is designed for max. Effie. at 100% load as it always runs at 100% load being near to generating station. 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. as per the design is concerned 1)the flux density is higher than the distributin transformer. 2) power transformers are normally having higher voltage (KV)and capacities (KVA). 3) Power transformer are so designed that they will have Max. efficency at rated full load and the distribution transformers will have max. efficency at 50% loading.
what is the significance of KV & MVA rating of the transformer and how they are related. Answer In power transmission # 8 voltage are in K V
operating
ie Kilo Volt The transformers Capacity is in MVA ie Mega Volt Ampere In power Distribution Network operating Voltage in KV kilo Volt The transformer Capacity in KVA Power in 3h = Root3 VxI ---VA root 3VxI Cosphi---Watts
watts X 1000 =KW VA x 1000 = KVA Watts x 1000000 = MW KVA X 1000 = MVA
Induction Furnace
Induction Furnace has coil constructed from heavy copper tubing. It is designed and tuned to the inverter circuit which applies a medium frequency (generally 500 Hz or 1000 Hz) voltage to the Induction coil. The magnetic field produced by the induction coil induces eddy currents in the charge and heats it. Medium frequency is necessary to enhance the rate of heat generation. The inverter circuit requires for its operation a D.C. Voltage which is obtained by converting available three phase A.C. Voltage. Transformers which are used for transforming available three phase A.C. voltage to required voltage for converter circuit of the Induction Furnace are referred to as Induction Furnace Transformers. Thus they are essentially Rectifier/ Converter Duty Transformers. Depending on the rating of the rectifier transformers, input voltage is derived from standard three phase AC distribution voltages like 433 V, 3.3 kV, 6.6 kV, 11 kV, 22 kV, 33 kV etc. These become the primary (or line side) voltage of the transformer. Secondary (or cell side) voltage can be between 400 to 1000 V decided by the required D.C. output Voltage.
TECHNICAL DETAILS REQUIRED
Specification Of Transformer Required Consultant Project Rating ( KVA ) Voltage Ratio Quantity Vector Group Tapping Range Tap – Changer Steps Temp. Rise ( Oil / Wdg. ) No Laod Loss at rated Voltage & Frequency Full Load Loss at Principal Tap at 75 C Impedance at 75 C ( +10% to -10% Tol.) : : : : : : : : : :
:
:
:
Submit
define main transformer?
Transformer is a satatic device which transform power from one winding to another winding without change in frequency.
What is the difference between Busbar Chambar, MCCB board and MCB Board? How to choose to use which one in the system? BUS BAR CHAMBER : WHERE THE BUS BAR CONNECTED IN A VERTICAL ARRANGEMENT OR HORIZONTAL ARRANGEMENT WITH COVERED SURFACE IS CALLED BUS BAR CHAMBER. MCCB CHAMBER : WHERE THE MOTOR CONTROL CIRCUIT BREAKERS (MCCB) WILL FIXED ACCORDING TO GA OR BY CUSTOMER FEEDBACKS. MCB CHAMBER : WHERE THE MINIATURE CIRCUIT BREAKER(MCB) WILL BE FIXED ACCORDING TO THE PURPOSES GIVEN BY THE CUSTOMER e.g lighiting, motor ON/OFF.
What is Tan Delta Measurement in Transformers? How Does It Work? Tan Delta, also called Loss Angle or Dissipation Factor testing, is a diagnostic method of testing cables to determine the quality of the cable insulation. This is done to try to predict the remaining life expectancy and in order to prioritize cable replacement and/or injection. It is alsobuseful for determining what other tests may be worthwhile. If the insulation of a cable is free from defects, like water trees, electrical trees, moisture and air pockets, etc., the cable approaches the properties of a perfect capacitor. It is very similar to a parallel plate capacitor with the conductor and the neutral being the two plates separated by the insulation material. In a perfect capacitor, the voltage and current are phase shifted 90 degrees and the current through the insulation is capacitive. If there are impurities in the insulation, like those mentioned above, the resistance of the insulation decreases, resulting in an increase in resistive current through the insulation. It is no longer a perfect capacitor. The current and voltage will no longer be shifted 90 degrees. It will be something less than 90 degrees. The extent to which the phase shift is less than 90 degrees is indicative of the level of insulation contamination, hence quality/reliability. This “Loss Angle” is measured and analyzed. tan delta gives the ratio of resistive current to capacitive current.therefore it shows the amount of resistive current flowing through the insulation,in other words it denoted the dielectric strength of bushing. tan delta (loss angle ) and cap is taken of the enquipment such as CTs and TRF bushings wherein paper and other material is utilised in its insulation. tan delta and cap values indicates to you the condition of the bushing insulation. if a plot is plotted aginst the no of years of the bushing in service and the value of tan delta taken every year, you shall get the trend of insulation detoriation.the higher side of tan delta value is 0.007.
why corona ring is used in out door switchyard lightning arrestor?
corona is the function of partial discharge of air near the surface of the conductor due to high voltage (in kv) and high voltage above rated is possible only due to switching over voltage or lightning over voltage so the corona ring is provided near switch yard lightning arrestor
what is the different betweem earthing and neutral? Neutral comes out from node point of star winding. Any unbalance between three phases will reflect on neutral conductor. Earthing is a low resistive path for any short circuit or fault level. Earthing protects the equipment from damaging due to low resistive path. What is your weakness? I tended to be a perfectionist, therefore I didn’t like to delegate to others. But I have found out that in order to develop the organization, everyone in the organization must be experienced with many tasks and this is very good for an efficient team work. Different Earthings: Grounding is provided for the safety of the equipment, while earthing is provided for the safety of human beings. Ground make faulty current drawn in overall circuit. earth is make individual circuit mean ups, dg lighting circuit etc..... EARTHING SYSTEMS These have been designated in the IEE Regulations using the letters: T, N, C and S. These letters stand for: T - terre (French for earth) and meaning a direct connection to earth. N - neutral C - combined S - separate. When these letters are grouped, they form the classification of a type of system. The first letter denotes how the supply source is earthed. The second denotes how the metalwork of an installation is earthed. The third and fourth indicate the functions of neutral and protective conductors. TT SYSTEM : A TT system has a direct connection to the supply source to earth and a direct connection of the installation metalwork to earth. An example is an overhead line supply with earth electrodes, and the mass of earth as a return path as shown below. Note that only single-phase systems have been shown for simplicity. TN-S SYSTEM A TN-S system has the supply source directly connected to earth, the installation metalwork connected to the neutral of the supply source via the lead sheath of the supply cable, and the neutral and protective conductors throughout the whole system performing separate functions. The resistance around the loop P-B-N-E should be no more than 0.8 ohms. TN-C-S SYSTEM A TN-C-S system is as the TN-S but the supply cable sheath is also the neutral, i.e. it forms a combined earth/neutral conductor known as a PEN (protective earthed neutral) conductor. The installation earth and neutral are separate conductors.This system is also known as PME (protective multiple earthing). The resistance around the P-B-N-N loop should be less than 0.35 ohms. SUMMARY OF EARTHING SYSTEMS
The TT method is used mostly in country areas with overhead transmission lines. In contrast to the TN-S system there is no metallic path from the consumer's terminals back to the sub-station transformer secondary windings. Because the earth path may be of high resistance, a residual current circuit-breaker (R.C.C.B.) is often fitted so that if a fault current flows in the earth path then a trip disconnects the phase supply. For protection against indirect contact in domestic premises, every socket outlet requires an RCCB with a maximum rated current of 30mA. The TN-S system of wiring uses the incoming cable sheath as the earth return path and the phase and neutral have separate conductors. The neutral is then connected to earth back at the transformer substation. Remember in TN-S, the T stands for earth (terre), N for neutral and S denotes that the protective (earth) and neutral conductors are separate.
The TN-C-S system has only two conductors in the incoming cable, one phase and the other neutral. The earth is linked to the neutral at the consumer unit. The neutral therefore is really a combined earth/neutral conductor hence the name PME. In order to avoid the risk of serious electric shock, it is important to provide a path for earth leakage currents to operate the circuit protection, and to endeavour to maintain all metalwork at the same potential. This is achieved by bonding together all metalwork of electrical and non-electrical systems to earth. The path for leakage currents would then be via the earth itself in TT systems or by a metallic return path in TN-S or TN-C-S systems. NOTES Older houses in towns use TNS (solid) i.e. separate earth say cable sheath. Around Towns new houses use (PME) TNCS i.e. neutral and earth shared. Single House in country with own transformer uses TT i.e. own buried earth electrode. Petrol stations, Swimming pools, Changing rooms etc. are not allowed to be PME. Transformer Principle : Transformer basically works on principal of MUTUAL INDUCTION.
why the transformer neutral point connected to earth? 1. Earth fault protection 2. Sustaining unbalanced load 3. Completing returning path of transmission line Explaining HOW? If single line to ground fault occurs on isolated(neutral not grounded) transformer. No return path is available so, no current will flow with this line. This will result in increase in voltage of other two line which is unfaulted. This high voltage may lead to stress on insulation and may cause of insulation failure. At the distribution end, load to each line is not equal. If they are equal then no problem at all without neutralizing. But if load are unbalanced(most common case). Neutral current will not be 0. So, we need to provide path for it, otherwise again same problem and result in insulation failure Sometimes, it complete the circuit through earth and we don't need extra wire to carry returning current
what is the purpose of zig zag transformer? . How it is different from normal transformer? A Zigzag transformer is a special purpose transformer with a zigzag arrangement. It has primary windings but no secondary winding. One application is to derive an earth reference point for an ungrounded electrical system. Another is to control harmonic currents.
What is the meaning of Dyn11 of Transformer. Answer First symbol/symbols, capital # 8 letters: HV winding connection.
Second symbol/symbols, small letters: LV winding connection. Third symbol, number: Phase displacement expressed as the clock hour number. Winding connection designations High Voltage Always capital letters Delta - D Star - S Interconnected star - Z Neutral brought out - N Low voltage Always small letters Delta - d Star - s Interconnected star - z Neutral brought out - n Phase displacement Phase rotation is always anticlockwise. (international adopted convention) Use the hour indicator as the indicating phase displacement angle. Because there are 12 hours on a clock, and a circle consists out of 360°, each hour represents 30°. Thus 1 = 30°, 2 = 60°, 3 = 90°, 6 = 180° and 12 = 0° or 360°. The minute hand is set on 12 o'clock and replaces the line to neutral voltage (sometimes
imaginary) of the HV winding. This position is always the reference point. Because rotation is anti-clockwise, 1 = 30° lagging (LV lags HV with 30°)and 11 = 330° lagging or 30° leading (LV leads HV with 30°) To summarise: Dyn11 Delta connected HV winding, star connected LV winding with neutral brought out, LV is leading HV with 30°
Transformers are classified as two categories: power transformers and distribution transformers. Power transformers are used in transmission network of higher voltages, deployed for step-up and step down transformer application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) Distribution transformers are used for lower voltage distribution networks as a means to end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V)the main difference between power and distribution transformer is, distribution transf. is designed for max. efficiency at 60% to 70% load as normally doesnt operate at full load all the time. Its load depends on distribution demand. Where as power transf. is designed for max. Effie. at 100% load as it always runs at 100% load being near to generating station. 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. as per the design is concerned 1)the flux density is higher than the distributin transformer. 2) power transformers are normally having higher voltage (KV)and capacities (KVA). 3) Power transformer are so designed that they will have Max. efficency at rated full load and the distribution transformers will have max. efficency at 50% loading.
what is the significance of KV & MVA rating of the transformer and how they are related. Answer In power transmission # 8 voltage are in K V
operating
ie Kilo Volt The transformers Capacity is in MVA ie Mega Volt Ampere In power Distribution Network operating Voltage in KV kilo Volt The transformer Capacity in KVA Power in 3h = Root3 VxI ---VA root 3VxI Cosphi---Watts
watts X 1000 =KW VA x 1000 = KVA Watts x 1000000 = MW KVA X 1000 = MVA
Induction Furnace
Induction Furnace has coil constructed from heavy copper tubing. It is designed and tuned to the inverter circuit which applies a medium frequency (generally 500 Hz or 1000 Hz) voltage to the Induction coil. The magnetic field produced by the induction coil induces eddy currents in the charge and heats it. Medium frequency is necessary to enhance the rate of heat generation. The inverter circuit requires for its operation a D.C. Voltage which is obtained by converting available three phase A.C. Voltage. Transformers which are used for transforming available three phase A.C. voltage to required voltage for converter circuit of the Induction Furnace are referred to as Induction Furnace Transformers. Thus they are essentially Rectifier/ Converter Duty Transformers. Depending on the rating of the rectifier transformers, input voltage is derived from standard three phase AC distribution voltages like 433 V, 3.3 kV, 6.6 kV, 11 kV, 22 kV, 33 kV etc. These become the primary (or line side) voltage of the transformer. Secondary (or cell side) voltage can be between 400 to 1000 V decided by the required D.C. output Voltage.
TECHNICAL DETAILS REQUIRED
Specification Of Transformer Required Consultant Project Rating ( KVA ) Voltage Ratio Quantity Vector Group Tapping Range Tap – Changer Steps Temp. Rise ( Oil / Wdg. ) No Laod Loss at rated Voltage & Frequency Full Load Loss at Principal Tap at 75 C Impedance at 75 C ( +10% to -10% Tol.) : : : : : : : : : :
:
:
:
Submit
define main transformer?
Transformer is a satatic device which transform power from one winding to another winding without change in frequency.
What is the difference between Busbar Chambar, MCCB board and MCB Board? How to choose to use which one in the system? BUS BAR CHAMBER : WHERE THE BUS BAR CONNECTED IN A VERTICAL ARRANGEMENT OR HORIZONTAL ARRANGEMENT WITH COVERED SURFACE IS CALLED BUS BAR CHAMBER. MCCB CHAMBER : WHERE THE MOTOR CONTROL CIRCUIT BREAKERS (MCCB) WILL FIXED ACCORDING TO GA OR BY CUSTOMER FEEDBACKS. MCB CHAMBER : WHERE THE MINIATURE CIRCUIT BREAKER(MCB) WILL BE FIXED ACCORDING TO THE PURPOSES GIVEN BY THE CUSTOMER e.g lighiting, motor ON/OFF.
What is Tan Delta Measurement in Transformers? How Does It Work? Tan Delta, also called Loss Angle or Dissipation Factor testing, is a diagnostic method of testing cables to determine the quality of the cable insulation. This is done to try to predict the remaining life expectancy and in order to prioritize cable replacement and/or injection. It is alsobuseful for determining what other tests may be worthwhile. If the insulation of a cable is free from defects, like water trees, electrical trees, moisture and air pockets, etc., the cable approaches the properties of a perfect capacitor. It is very similar to a parallel plate capacitor with the conductor and the neutral being the two plates separated by the insulation material. In a perfect capacitor, the voltage and current are phase shifted 90 degrees and the current through the insulation is capacitive. If there are impurities in the insulation, like those mentioned above, the resistance of the insulation decreases, resulting in an increase in resistive current through the insulation. It is no longer a perfect capacitor. The current and voltage will no longer be shifted 90 degrees. It will be something less than 90 degrees. The extent to which the phase shift is less than 90 degrees is indicative of the level of insulation contamination, hence quality/reliability. This “Loss Angle” is measured and analyzed. tan delta gives the ratio of resistive current to capacitive current.therefore it shows the amount of resistive current flowing through the insulation,in other words it denoted the dielectric strength of bushing. tan delta (loss angle ) and cap is taken of the enquipment such as CTs and TRF bushings wherein paper and other material is utilised in its insulation. tan delta and cap values indicates to you the condition of the bushing insulation. if a plot is plotted aginst the no of years of the bushing in service and the value of tan delta taken every year, you shall get the trend of insulation detoriation.the higher side of tan delta value is 0.007.
why corona ring is used in out door switchyard lightning arrestor?
corona is the function of partial discharge of air near the surface of the conductor due to high voltage (in kv) and high voltage above rated is possible only due to switching over voltage or lightning over voltage so the corona ring is provided near switch yard lightning arrestor
what is the different betweem earthing and neutral? Neutral comes out from node point of star winding. Any unbalance between three phases will reflect on neutral conductor. Earthing is a low resistive path for any short circuit or fault level. Earthing protects the equipment from damaging due to low resistive path. What is your weakness? I tended to be a perfectionist, therefore I didn’t like to delegate to others. But I have found out that in order to develop the organization, everyone in the organization must be experienced with many tasks and this is very good for an efficient team work. Different Earthings: Grounding is provided for the safety of the equipment, while earthing is provided for the safety of human beings. Ground make faulty current drawn in overall circuit. earth is make individual circuit mean ups, dg lighting circuit etc..... EARTHING SYSTEMS These have been designated in the IEE Regulations using the letters: T, N, C and S. These letters stand for: T - terre (French for earth) and meaning a direct connection to earth. N - neutral C - combined S - separate. When these letters are grouped, they form the classification of a type of system. The first letter denotes how the supply source is earthed. The second denotes how the metalwork of an installation is earthed. The third and fourth indicate the functions of neutral and protective conductors. TT SYSTEM : A TT system has a direct connection to the supply source to earth and a direct connection of the installation metalwork to earth. An example is an overhead line supply with earth electrodes, and the mass of earth as a return path as shown below. Note that only single-phase systems have been shown for simplicity. TN-S SYSTEM A TN-S system has the supply source directly connected to earth, the installation metalwork connected to the neutral of the supply source via the lead sheath of the supply cable, and the neutral and protective conductors throughout the whole system performing separate functions. The resistance around the loop P-B-N-E should be no more than 0.8 ohms. TN-C-S SYSTEM A TN-C-S system is as the TN-S but the supply cable sheath is also the neutral, i.e. it forms a combined earth/neutral conductor known as a PEN (protective earthed neutral) conductor. The installation earth and neutral are separate conductors.This system is also known as PME (protective multiple earthing). The resistance around the P-B-N-N loop should be less than 0.35 ohms. SUMMARY OF EARTHING SYSTEMS
The TT method is used mostly in country areas with overhead transmission lines. In contrast to the TN-S system there is no metallic path from the consumer's terminals back to the sub-station transformer secondary windings. Because the earth path may be of high resistance, a residual current circuit-breaker (R.C.C.B.) is often fitted so that if a fault current flows in the earth path then a trip disconnects the phase supply. For protection against indirect contact in domestic premises, every socket outlet requires an RCCB with a maximum rated current of 30mA. The TN-S system of wiring uses the incoming cable sheath as the earth return path and the phase and neutral have separate conductors. The neutral is then connected to earth back at the transformer substation. Remember in TN-S, the T stands for earth (terre), N for neutral and S denotes that the protective (earth) and neutral conductors are separate.
The TN-C-S system has only two conductors in the incoming cable, one phase and the other neutral. The earth is linked to the neutral at the consumer unit. The neutral therefore is really a combined earth/neutral conductor hence the name PME. In order to avoid the risk of serious electric shock, it is important to provide a path for earth leakage currents to operate the circuit protection, and to endeavour to maintain all metalwork at the same potential. This is achieved by bonding together all metalwork of electrical and non-electrical systems to earth. The path for leakage currents would then be via the earth itself in TT systems or by a metallic return path in TN-S or TN-C-S systems. NOTES Older houses in towns use TNS (solid) i.e. separate earth say cable sheath. Around Towns new houses use (PME) TNCS i.e. neutral and earth shared. Single House in country with own transformer uses TT i.e. own buried earth electrode. Petrol stations, Swimming pools, Changing rooms etc. are not allowed to be PME. Transformer Principle : Transformer basically works on principal of MUTUAL INDUCTION.
why the transformer neutral point connected to earth? 1. Earth fault protection 2. Sustaining unbalanced load 3. Completing returning path of transmission line Explaining HOW? If single line to ground fault occurs on isolated(neutral not grounded) transformer. No return path is available so, no current will flow with this line. This will result in increase in voltage of other two line which is unfaulted. This high voltage may lead to stress on insulation and may cause of insulation failure. At the distribution end, load to each line is not equal. If they are equal then no problem at all without neutralizing. But if load are unbalanced(most common case). Neutral current will not be 0. So, we need to provide path for it, otherwise again same problem and result in insulation failure Sometimes, it complete the circuit through earth and we don't need extra wire to carry returning current
what is the purpose of zig zag transformer? . How it is different from normal transformer? A Zigzag transformer is a special purpose transformer with a zigzag arrangement. It has primary windings but no secondary winding. One application is to derive an earth reference point for an ungrounded electrical system. Another is to control harmonic currents.
What is the meaning of Dyn11 of Transformer. Answer First symbol/symbols, capital # 8 letters: HV winding connection.
Second symbol/symbols, small letters: LV winding connection. Third symbol, number: Phase displacement expressed as the clock hour number. Winding connection designations High Voltage Always capital letters Delta - D Star - S Interconnected star - Z Neutral brought out - N Low voltage Always small letters Delta - d Star - s Interconnected star - z Neutral brought out - n Phase displacement Phase rotation is always anticlockwise. (international adopted convention) Use the hour indicator as the indicating phase displacement angle. Because there are 12 hours on a clock, and a circle consists out of 360°, each hour represents 30°. Thus 1 = 30°, 2 = 60°, 3 = 90°, 6 = 180° and 12 = 0° or 360°. The minute hand is set on 12 o'clock and replaces the line to neutral voltage (sometimes
imaginary) of the HV winding. This position is always the reference point. Because rotation is anti-clockwise, 1 = 30° lagging (LV lags HV with 30°)and 11 = 330° lagging or 30° leading (LV leads HV with 30°) To summarise: Dyn11 Delta connected HV winding, star connected LV winding with neutral brought out, LV is leading HV with 30°
