Cause the reason with three-phase lopsided voltage to have a variety of, be like: The single-phase ground connection, resonance that break a string, moving administrator distinguishs his correctly only come, ability is handled quickly.
One, the breakdown that break a string
If one photograph breaks a string but not ground connection, or breaker, switch-disconnector did not put through, fusing of voltage transformer fuse all creates three-phase parameter asymmetry. When circuitry of grade of on one voltage breaks a string, the volmeter of grade of below one voltage is 3 phase voltage to be reduced now, among them one photograph is inferior, additional two-phase is taller but both voltage value is adjacent. When this class circuitry breaks a string, the phase voltage that break a string is 0, did not break line phase voltage to still be phase voltage.
2, ground connection breakdown
When circuit one photograph breaks a string and when single-phase ground connection, although cause three phase voltage lopsided, but value of the voltage after ground connection is not changed. Sheet divides ground connection of the attribute that it is gold and metalloid sex ground connection conterminously two kinds. Metallic sex ground connection, breakdown phase voltage is 0 or adjacent 0, blame breakdown phase voltage is 1.732 times more elevatory, and abiding and changeless; Metalloid sex ground connection, ground connection phase voltage is 0 reduce however for some numerical value, other two-phase does not lift 1.732 times.
3, syntonic reason
As flying development of industry, nonlinear power load increases in great quantities, certain bear produces harmonic not only, still cause wave motion of power supply voltage and flicker, cause three-phase tension even lopsided.
1, resonance causes three-phase tension lopsided have two kinds:
One kind is fundamental frequency resonance, the feature is similar to single-phase ground connection, namely one phase voltage is reduced, additional two-phase voltage is elevatory, when searching breakdown account find breakdown place not easily, can check special user right now, reason of except ground connection, resonance causes the likelihood.
Another kind is scale down resonance or high frequency resonance, the feature is three-phase voltage lifts at the same time.
Additional, notice even, when airdrop generatrix excises partial route or breakdown of odd conterminous ground disappears, be like signal of occurrence ground connection, and one photograph, two-phase or three-phase voltage exceed line voltage, volmeter finger hits in the end, and at the same time slow shift, or three-phase voltage lifts by turns exceed line voltage, encounter this kind of situation, all belong to resonance to cause commonly.
2, the harm with lopsided three-phase and influence:
(1) the harm to transformer.
Phone is used in production, life in, when three-phase load is lopsided, make transformer is in asymmetry to run state. The loss that causes transformer increases (include to carry loss and laden loss) for nothing. Run regulations to set according to transformer, in the transformer neutral in moving line electric current must not exceed side of transformer low pressure 25% of rated electric current. In addition, lopsided moving meeting causes three-phase load 0 foreword electric current crosses transformer big, local metal warm up heighten, can bring about transformer burn down even.
(2) to using the influence of electric equipment.
The happening with three-phase lopsided voltage will be brought about achieve multiple the happening with lopsided electric current. Torque is gone against to increase in revulsive electromotor, make the temperature of electromotor rises thereby, efficiency drops, specific power consumption increases, happen shake, output the influence such as loss by a natural process. The lopsided meeting between each photograph brings about the service life of equipment that use phone to shorten, quicken equipment component to change frequency, raise the cost that equipment maintains. Breaker allows voltaic surplus to decrease, be changed when load or alternant when phenomenon of incidental overload, short circuit. Neuter line midstream has entered big lopsided electric current, bring about neuter line to add thick.
(3) the influence to line caustic.
4 lines make three-phase tie line means, when three-phase bear is balanced line damage is the least; Lose loading when one photograph, the circumstance with two-phase small negative charge gets offline caustic increment is lesser; Lose loading when one photograph, one photograph negative charge is small, and the bear of three-phase gets offline for the circumstance of average negative charge caustic increment is bigger; When one photograph bear light, the circumstance with two-phase heavy load gets offline caustic increment is the biggest. When three-phase bear is lopsided, no matter why be planted bear allocation circumstance, electric current is lopsided degree bigger, line caustic increment is bigger also.
3, the harm with lopsided three-phase and settle way:
Three-phase voltage or electric current are lopsided the main harm that waits for element generation:
(1) rotate electric machinery moves below asymmetry condition, can make rotor produces additional loss to reach calorific, cause electric machinery whole thereby or local warm up, in addition retrorse magnetic field produces add moment of force to be able to make electric machinery appears oscillatory. To the dynamo character, still can form in stator a series of tall second harmonic.
(2) cause what be the component that start with negative phase-sequence heft a variety of protection produce misoperation, direct and minatory electrified wire netting moves.
(3) lopsided voltage makes silicon commutate equipment appears harmonic of blame feature sex.
(4) to dynamo, transformer character, when three-phase bear is lopsided, if control the biggest phase current to be rating, criterion the others two-phase cannot is fully loaded with, consequently utilization rate of equipment and installations drops, if want,maintain nominal capacity conversely, will cause the one look with bigger negative charge to pass negative charge, and still can appear magnetic circuit is lopsided cause undee distortion, additional loss adds equipment etc.
4, the tension of three-phase of electrified wire netting that causes by asymmetry bear is lopsided can adopt settle way:
(1) receive asymmetry bear dispersedly nod in different power supply, with reducing concentration join is caused lopsided degree of problem that exceeds bid badly.
(2) the method such as use across commutation makes asymmetry bear reasonable allocate each photograph, make its are changed evenly as far as possible.
(3) the short circuit size that increases bear to receive a point, be like change network or raise level of power supply tension to raise a system to bear the ability of lopsided bear.
5, solve a few measure with three-phase lopsided bear:
(1) the program that values low-pressure distribution network works, strengthen the job that plans to wait for a branch with local government to communicate, avoid distribution network construction not to have foreword, in avoiding to match electrified wire netting in low pressure especially, appear have a headache cure head, the situation of foot of crural painful medical service, be built in distribution network and transform in the center undertake to low-pressure stage area reasonable partition distributes a power supply, deserve to change cloth dot approachs bear center as far as possible, avoid fan power supply and circuitous power supply, the construction of distribution network should be abided by " dot of small size, much cloth, short radius " deserve to change optional location principle.
(2) the region that in low-pressure to using three-phase 4 lines make power supply, should strive for pair of conditional distribution stage areas actively to use 3 core or 4 core cable perhaps uses power supply of low-pressure colonies lead to the client side, so OK of the oldest in construction of road of low line ball rate avoid three-phase bear to appear slant the occurrence of the photograph, should do very low-pressure outfit to express the job at the same time, single-phase ammeter is in of three-phase of A, B, C distributing as far as possible even, avoid to appear single-phase report is hanged only receive in one photograph or on two-phase, online journey fag end causes bear to slant.
(3) in low-pressure distribution network 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy. At present as a result of three-phase bear distributing lopsided, brought about 0 lines occurrence electric current, ask according to regulations 0 lines electric current must not exceed 25% of look line electric current, in effective use line of business, because 0 wires wire is sectional fine, resistance is more identical the look line of length is big, 0 lines electric current passes to go up to also can cause loss of certain proportional electric energy in lead greatly, so the proposal matchs electrified wire netting in low pressure public advocate 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy, the tension that the 0 lines electricity that because bear is lopsided,avoids to appear produces endangers person security badly, and nod ground connection through how, bring down because give out heat,the 0 lines that wait for a reason to cause are broken break a string, make the phase voltage that the user uses elevatory, attaint electric home appliances (4) active to the power supply area that single-phase bear occupies larger proportion promotion is single-phase change power supply. At present major inside townsman village laden electric equipment is to use single-phase phone, because line negative charge is motivation, illume to mix mostly,carry, and rate is inferior while electric equipment is used, such making low-pressure three-phase bear is running medium lopsided range actually bigger. Additional from at present rural life looks with electric circumstance, in a lot of owe develop and the country of underdeveloped area is existing average per capita uses n small, live dispersive, power supply line is long wait for a problem, can consider to these areas the more dispersive to the user, bear that use phone basically is given priority to with illume, the case with not big negative charge, use the means that uses single-phase transformer power supply, reduce loss and the goal that build capital in order to amount to. At present single-phase transformer loss ratio reduces 15 ％ ～ with capacity three-phase transformer 20 ％ , what some manufacturer produce is single-phase change in low-pressure side OK and derivative 380V is mixed 220V grade of two kinds of voltage, already also began in a few areas at the same time use much station single-phase change to three-phase bear power supply pilot, to use single-phase change power supply provided more vast space. (5) begin transformer actively to bear is measured actually and adjust the job. The job of bear actual measurement that deserves to change looks be like simple, but a few is there to need to notice in real work, it is actual measurement job cannot be measured simply deserve to become low-pressure three-phase of side A, B, C is derivative the phase current of the line, and should measure 0 on-line electric current, perhaps measure 0 lines (row) right voltage, can give the lopsided case of three-phase bear quite better thereby, 2 it is actual measurement the fag end that the job wants to match electrical wiring road to low pressure and branch end are outspread, can discover the occurrence site of lopsided bear further so, define the point that move carry on one's shoulder, 3 it is bear actual measurement the job should be begun regularly already also otherwise is begun regularly, cast in big user negative charge especially carry and be during height bear, want to increase the number of actual measurement, deserve to become low-pressure to give line and the low-pressure circuitry electric current that are close to the client side through seasonable measurement, facilitate accurate ground understands the moving situation of equipment, do the balanced and reasonable allocation of good bear. Cause the reason with three-phase lopsided voltage to have a variety of, be like: The single-phase ground connection, resonance that break a string, moving administrator distinguishs his correctly only come, ability is handled quickly. One, the breakdown that break a string If one photograph breaks a string but not ground connection, or breaker, switch-disconnector did not put through, fusing of voltage transformer fuse all creates three-phase parameter asymmetry. When circuitry of grade of on one voltage breaks a string, the volmeter of grade of below one voltage is 3 phase voltage to be reduced now, among them one photograph is inferior, additional two-phase is taller but both voltage value is adjacent. When this class circuitry breaks a string, the phase voltage that break a string is 0, did not break line phase voltage to still be phase voltage. 2, ground connection breakdown When circuit one photograph breaks a string and when single-phase ground connection, although cause three phase voltage lopsided, but value of the voltage after ground connection is not changed. Sheet divides ground connection of the attribute that it is gold and metalloid sex ground connection conterminously two kinds. Metallic sex ground connection, breakdown phase voltage is 0 or adjacent 0, blame breakdown phase voltage is 1.732 times more elevatory, and abiding and changeless; Metalloid sex ground connection, ground connection phase voltage is 0 reduce however for some numerical value, other two-phase does not lift 1.732 times. 3, syntonic reason As flying development of industry, nonlinear power load increases in great quantities, certain bear produces harmonic not only, still cause wave motion of power supply voltage and flicker, cause three-phase tension even lopsided. 1, resonance causes three-phase tension lopsided have two kinds: One kind is fundamental frequency resonance, the feature is similar to single-phase ground connection, namely one phase voltage is reduced, additional two-phase voltage is elevatory, when searching breakdown account find breakdown place not easily, can check special user right now, reason of except ground connection, resonance causes the likelihood. Another kind is scale down resonance or high frequency resonance, the feature is three-phase voltage lifts at the same time. Additional, notice even, when airdrop generatrix excises partial route or breakdown of odd conterminous ground disappears, be like signal of occurrence ground connection, and one photograph, two-phase or three-phase voltage exceed line voltage, volmeter finger hits in the end, and at the same time slow shift, or three-phase voltage lifts by turns exceed line voltage, encounter this kind of situation, all belong to resonance to cause commonly. 2, the harm with lopsided three-phase and influence: (1) the harm to transformer. Phone is used in production, life in, when three-phase load is lopsided, make transformer is in asymmetry to run state. The loss that causes transformer increases (include to carry loss and laden loss) for nothing. Run regulations to set according to transformer, in the transformer neutral in moving line electric current must not exceed side of transformer low pressure 25% of rated electric current. In addition, lopsided moving meeting causes three-phase load 0 foreword electric current crosses transformer big, local metal warm up heighten, can bring about transformer burn down even. (2) to using the influence of electric equipment. The happening with three-phase lopsided voltage will be brought about achieve multiple the happening with lopsided electric current. Torque is gone against to increase in revulsive electromotor, make the temperature of electromotor rises thereby, efficiency drops, specific power consumption increases, happen shake, output the influence such as loss by a natural process. The lopsided meeting between each photograph brings about the service life of equipment that use phone to shorten, quicken equipment component to change frequency, raise the cost that equipment maintains. Breaker allows voltaic surplus to decrease, be changed when load or alternant when phenomenon of incidental overload, short circuit. Neuter line midstream has entered big lopsided electric current, bring about neuter line to add thick. (3) the influence to line caustic. 4 lines make three-phase tie line means, when three-phase bear is balanced line damage is the least; Lose loading when one photograph, the circumstance with two-phase small negative charge gets offline caustic increment is lesser; Lose loading when one photograph, one photograph negative charge is small, and the bear of three-phase gets offline for the circumstance of average negative charge caustic increment is bigger; When one photograph bear light, the circumstance with two-phase heavy load gets offline caustic increment is the biggest. When three-phase bear is lopsided, no matter why be planted bear allocation circumstance, electric current is lopsided degree bigger, line caustic increment is bigger also. 3, the harm with lopsided three-phase and settle way: Three-phase voltage or electric current are lopsided the main harm that waits for element generation: (1) rotate electric machinery moves below asymmetry condition, can make rotor produces additional loss to reach calorific, cause electric machinery whole thereby or local warm up, in addition retrorse magnetic field produces add moment of force to be able to make electric machinery appears oscillatory. To the dynamo character, still can form in stator a series of tall second harmonic. (2) cause what be the component that start with negative phase-sequence heft a variety of protection produce misoperation, direct and minatory electrified wire netting moves. (3) lopsided voltage makes silicon commutate equipment appears harmonic of blame feature sex. (4) to dynamo, transformer character, when three-phase bear is lopsided, if control the biggest phase current to be rating, criterion the others two-phase cannot is fully loaded with, consequently utilization rate of equipment and installations drops, if want,maintain nominal capacity conversely, will cause the one look with bigger negative charge to pass negative charge, and still can appear magnetic circuit is lopsided cause undee distortion, additional loss adds equipment etc. 4, the tension of three-phase of electrified wire netting that causes by asymmetry bear is lopsided can adopt settle way: (1) receive asymmetry bear dispersedly nod in different power supply, with reducing concentration join is caused lopsided degree of problem that exceeds bid badly. (2) the method such as use across commutation makes asymmetry bear reasonable allocate each photograph, make its are changed evenly as far as possible. (3) the short circuit size that increases bear to receive a point, be like change network or raise level of power supply tension to raise a system to bear the ability of lopsided bear. 5, solve a few measure with three-phase lopsided bear: (1) the program that values low-pressure distribution network works, strengthen the job that plans to wait for a branch with local government to communicate, avoid distribution network construction not to have foreword, in avoiding to match electrified wire netting in low pressure especially, appear have a headache cure head, the situation of foot of crural painful medical service, be built in distribution network and transform in the center undertake to low-pressure stage area reasonable partition distributes a power supply, deserve to change cloth dot approachs bear center as far as possible, avoid fan power supply and circuitous power supply, the construction of distribution network should be abided by " dot of small size, much cloth, short radius " deserve to change optional location principle. (2) the region that in low-pressure to using three-phase 4 lines make power supply, should strive for pair of conditional distribution stage areas actively to use 3 core or 4 core cable perhaps uses power supply of low-pressure colonies lead to the client side, so OK of the oldest in construction of road of low line ball rate avoid three-phase bear to appear slant the occurrence of the photograph, should do very low-pressure outfit to express the job at the same time, single-phase ammeter is in of three-phase of A, B, C distributing as far as possible even, avoid to appear single-phase report is hanged only receive in one photograph or on two-phase, online journey fag end causes bear to slant. (3) in low-pressure distribution network 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy. At present as a result of three-phase bear distributing lopsided, brought about 0 lines occurrence electric current, ask according to regulations 0 lines electric current must not exceed 25% of look line electric current, in effective use line of business, because 0 wires wire is sectional fine, resistance is more identical the look line of length is big, 0 lines electric current passes to go up to also can cause loss of certain proportional electric energy in lead greatly, so the proposal matchs electrified wire netting in low pressure public advocate 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy, the tension that the 0 lines electricity that because bear is lopsided,avoids to appear produces endangers person security badly, and nod ground connection through how, bring down because give out heat,the 0 lines that wait for a reason to cause are broken break a string, make the phase voltage that the user uses elevatory, attaint electric home appliances (4) active to the power supply area that single-phase bear occupies larger proportion promotion is single-phase change power supply. At present major inside townsman village laden electric equipment is to use single-phase phone, because line negative charge is motivation, illume to mix mostly,carry, and rate is inferior while electric equipment is used, such making low-pressure three-phase bear is running medium lopsided range actually bigger. Additional from at present rural life looks with electric circumstance, in a lot of owe develop and the country of underdeveloped area is existing average per capita uses n small, live dispersive, power supply line is long wait for a problem, can consider to these areas the more dispersive to the user, bear that use phone basically is given priority to with illume, the case with not big negative charge, use the means that uses single-phase transformer power supply, reduce loss and the goal that build capital in order to amount to. At present single-phase transformer loss ratio reduces 15 ％ ～ with capacity three-phase transformer 20 ％ , what some manufacturer produce is single-phase change in low-pressure side OK and derivative 380V is mixed 220V grade of two kinds of voltage, already also began in a few areas at the same time use much station single-phase change to three-phase bear power supply pilot, to use single-phase change power supply provided more vast space. (5) begin transformer actively to bear is measured actually and adjust the job. The job of bear actual measurement that deserves to change looks be like simple, but a few is there to need to notice in real work, it is actual measurement job cannot be measured simply deserve to become low-pressure three-phase of side A, B, C is derivative the phase current of the line, and should measure 0 on-line electric current, perhaps measure 0 lines (row) right voltage, can give the lopsided case of three-phase bear quite better thereby, 2 it is actual measurement the fag end that the job wants to match electrical wiring road to low pressure and branch end are outspread, can discover the occurrence site of lopsided bear further so, define the point that move carry on one's shoulder, 3 it is bear actual measurement the job should be begun regularly already also otherwise is begun regularly, cast in big user negative charge especially carry and be during height bear, want to increase the number of actual measurement, deserve to become low-pressure to give line and the low-pressure circuitry electric current that are close to the client side through seasonable measurement, facilitate accurate ground understands the moving situation of equipment, do the balanced and reasonable allocation of good bear. Cause the reason with three-phase lopsided voltage to have a variety of, be like: The single-phase ground connection, resonance that break a string, moving administrator distinguishs his correctly only come, ability is handled quickly. One, the breakdown that break a string If one photograph breaks a string but not ground connection, or breaker, switch-disconnector did not put through, fusing of voltage transformer fuse all creates three-phase parameter asymmetry. When circuitry of grade of on one voltage breaks a string, the volmeter of grade of below one voltage is 3 phase voltage to be reduced now, among them one photograph is inferior, additional two-phase is taller but both voltage value is adjacent. When this class circuitry breaks a string, the phase voltage that break a string is 0, did not break line phase voltage to still be phase voltage. 2, ground connection breakdown When circuit one photograph breaks a string and when single-phase ground connection, although cause three phase voltage lopsided, but value of the voltage after ground connection is not changed. Sheet divides ground connection of the attribute that it is gold and metalloid sex ground connection conterminously two kinds. Metallic sex ground connection, breakdown phase voltage is 0 or adjacent 0, blame breakdown phase voltage is 1.732 times more elevatory, and abiding and changeless; Metalloid sex ground connection, ground connection phase voltage is 0 reduce however for some numerical value, other two-phase does not lift 1.732 times. 3, syntonic reason As flying development of industry, nonlinear power load increases in great quantities, certain bear produces harmonic not only, still cause wave motion of power supply voltage and flicker, cause three-phase tension even lopsided. 1, resonance causes three-phase tension lopsided have two kinds: One kind is fundamental frequency resonance, the feature is similar to single-phase ground connection, namely one phase voltage is reduced, additional two-phase voltage is elevatory, when searching breakdown account find breakdown place not easily, can check special user right now, reason of except ground connection, resonance causes the likelihood. Another kind is scale down resonance or high frequency resonance, the feature is three-phase voltage lifts at the same time. Additional, notice even, when airdrop generatrix excises partial route or breakdown of odd conterminous ground disappears, be like signal of occurrence ground connection, and one photograph, two-phase or three-phase voltage exceed line voltage, volmeter finger hits in the end, and at the same time slow shift, or three-phase voltage lifts by turns exceed line voltage, encounter this kind of situation, all belong to resonance to cause commonly. 2, the harm with lopsided three-phase and influence: (1) the harm to transformer. Phone is used in production, life in, when three-phase load is lopsided, make transformer is in asymmetry to run state. The loss that causes transformer increases (include to carry loss and laden loss) for nothing. Run regulations to set according to transformer, in the transformer neutral in moving line electric current must not exceed side of transformer low pressure 25% of rated electric current. In addition, lopsided moving meeting causes three-phase load 0 foreword electric current crosses transformer big, local metal warm up heighten, can bring about transformer burn down even. (2) to using the influence of electric equipment. The happening with three-phase lopsided voltage will be brought about achieve multiple the happening with lopsided electric current. Torque is gone against to increase in revulsive electromotor, make the temperature of electromotor rises thereby, efficiency drops, specific power consumption increases, happen shake, output the influence such as loss by a natural process. The lopsided meeting between each photograph brings about the service life of equipment that use phone to shorten, quicken equipment component to change frequency, raise the cost that equipment maintains. Breaker allows voltaic surplus to decrease, be changed when load or alternant when phenomenon of incidental overload, short circuit. Neuter line midstream has entered big lopsided electric current, bring about neuter line to add thick. (3) the influence to line caustic. 4 lines make three-phase tie line means, when three-phase bear is balanced line damage is the least; Lose loading when one photograph, the circumstance with two-phase small negative charge gets offline caustic increment is lesser; Lose loading when one photograph, one photograph negative charge is small, and the bear of three-phase gets offline for the circumstance of average negative charge caustic increment is bigger; When one photograph bear light, the circumstance with two-phase heavy load gets offline caustic increment is the biggest. When three-phase bear is lopsided, no matter why be planted bear allocation circumstance, electric current is lopsided degree bigger, line caustic increment is bigger also. 3, the harm with lopsided three-phase and settle way: Three-phase voltage or electric current are lopsided the main harm that waits for element generation: (1) rotate electric machinery moves below asymmetry condition, can make rotor produces additional loss to reach calorific, cause electric machinery whole thereby or local warm up, in addition retrorse magnetic field produces add moment of force to be able to make electric machinery appears oscillatory. To the dynamo character, still can form in stator a series of tall second harmonic. (2) cause what be the component that start with negative phase-sequence heft a variety of protection produce misoperation, direct and minatory electrified wire netting moves. (3) lopsided voltage makes silicon commutate equipment appears harmonic of blame feature sex. (4) to dynamo, transformer character, when three-phase bear is lopsided, if control the biggest phase current to be rating, criterion the others two-phase cannot is fully loaded with, consequently utilization rate of equipment and installations drops, if want,maintain nominal capacity conversely, will cause the one look with bigger negative charge to pass negative charge, and still can appear magnetic circuit is lopsided cause undee distortion, additional loss adds equipment etc. 4, the tension of three-phase of electrified wire netting that causes by asymmetry bear is lopsided can adopt settle way: (1) receive asymmetry bear dispersedly nod in different power supply, with reducing concentration join is caused lopsided degree of problem that exceeds bid badly. (2) the method such as use across commutation makes asymmetry bear reasonable allocate each photograph, make its are changed evenly as far as possible. (3) the short circuit size that increases bear to receive a point, be like change network or raise level of power supply tension to raise a system to bear the ability of lopsided bear. 5, solve a few measure with three-phase lopsided bear: (1) the program that values low-pressure distribution network works, strengthen the job that plans to wait for a branch with local government to communicate, avoid distribution network construction not to have foreword, in avoiding to match electrified wire netting in low pressure especially, appear have a headache cure head, the situation of foot of crural painful medical service, be built in distribution network and transform in the center undertake to low-pressure stage area reasonable partition distributes a power supply, deserve to change cloth dot approachs bear center as far as possible, avoid fan power supply and circuitous power supply, the construction of distribution network should be abided by " dot of small size, much cloth, short radius " deserve to change optional location principle. (2) the region that in low-pressure to using three-phase 4 lines make power supply, should strive for pair of conditional distribution stage areas actively to use 3 core or 4 core cable perhaps uses power supply of low-pressure colonies lead to the client side, so OK of the oldest in construction of road of low line ball rate avoid three-phase bear to appear slant the occurrence of the photograph, should do very low-pressure outfit to express the job at the same time, single-phase ammeter is in of three-phase of A, B, C distributing as far as possible even, avoid to appear single-phase report is hanged only receive in one photograph or on two-phase, online journey fag end causes bear to slant. (3) in low-pressure distribution network 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy. At present as a result of three-phase bear distributing lopsided, brought about 0 lines occurrence electric current, ask according to regulations 0 lines electric current must not exceed 25% of look line electric current, in effective use line of business, because 0 wires wire is sectional fine, resistance is more identical the look line of length is big, 0 lines electric current passes to go up to also can cause loss of certain proportional electric energy in lead greatly, so the proposal matchs electrified wire netting in low pressure public advocate 0 lines use many bits of ground contact, reduce loss of 0 lines electric energy, the tension that the 0 lines electricity that because bear is lopsided,avoids to appear produces endangers person security badly, and nod ground connection through how, bring down because give out heat,the 0 lines that wait for a reason to cause are broken break a string, make the phase voltage that the user uses elevatory, attaint electric home appliances (4) active to the power supply area that single-phase bear occupies larger proportion promotion is single-phase change power supply. At present major inside townsman village laden electric equipment is to use single-phase phone, because line negative charge is motivation, illume to mix mostly,carry, and rate is inferior while electric equipment is used, such making low-pressure three-phase bear is running medium lopsided range actually bigger. Additional from at present rural life looks with electric circumstance, in a lot of owe develop and the country of underdeveloped area is existing average per capita uses n small, live dispersive, power supply line is long wait for a problem, can consider to these areas the more dispersive to the user, bear that use phone basically is given priority to with illume, the case with not big negative charge, use the means that uses single-phase transformer power supply, reduce loss and the goal that build capital in order to amount to. At present single-phase transformer loss ratio reduces 15 ％ ～ with capacity three-phase transformer 20 ％ , what some manufacturer produce is single-phase change in low-pressure side OK and derivative 380V is mixed 220V grade of two kinds of voltage, already also began in a few areas at the same time use much station single-phase change to three-phase bear power supply pilot, to use single-phase change power supply provided more vast space. (5) begin transformer actively to bear is measured actually and adjust the job. The job of bear actual measurement that deserves to change looks be like simple, but a few is there to need to notice in real work, it is actual measurement job cannot be measured simply deserve to become low-pressure three-phase of side A, B, C is derivative the phase current of the line, and should measure 0 on-line electric current, perhaps measure 0 lines (row) right voltage, can give the lopsided case of three-phase bear quite better thereby, 2 it is actual measurement the fag end that the job wants to match electrical wiring road to low pressure and branch end are outspread, can discover the occurrence site of lopsided bear further so, define the point that move carry on one's shoulder, 3 it is bear actual measurement the job should be begun regularly already also otherwise is begun regularly, cast in big user negative charge especially carry and be during height bear, want to increase the number of actual measurement, deserve to become low-pressure to give line and the low-pressure circuitry electric current that are close to the client side through seasonable measurement, facilitate accurate ground understands the moving situation of equipment, do the balanced and reasonable allocation of good bear.
