PRODUCT SHOW
SAI-358D digital transformer differential protection and control devices
I. Overview
Applicable to 110KV and below voltage dual ring, three times the transformer , to meet the requirements of the three sides of the differential . Also applies to generators or - transformer differential protection.
The main protection configuration features :
● differential speed off
● ratio of the second harmonic restraint differential
● CT disconnection locking differential
● cooling fault delay exports
Second, the principle that the protection of
2.1 , the differential speed off
When the current is greater than either move away from the differential speed off the setting value , the total exports of the relay action . Under severe fault conditions for the occurrence of rapid removal of the transformer in the transformer differential area. Should be able to determine the value of the differential speed to escape the maximum inrush current external fault current imbalance and airdrop transformer , and taking into account the current transformer saturation factor , generally take 6 to 12 times the rated current.
Its operating conditions are as follows :
Which is a differential current Id , Isd to determine the value of the differential speed
2.2 , the ratio of the differential
Conventional rate differential principle , its movement equation is as follows :
Id> Iqd Ir ≤ Ig
Id-Iqd> Kcd * (Ir-Ig) Ig <Ir ≤ 2.5Ie
Id-Iqd-Kcd * (3Ie-Ig)> 0.7 (Ir-2.5Ie) Ir> 2.5Ie
Kcd braking coefficient is the ratio
Iqd starting value for the differential current
Differential current Id is Id = | I1 + I2 + I3 |
Ir brake current Ir = 0.5 (| I1 | + | I2 | + | I3 |)
Because each side of the current transformer can be Y / △ adjusted by software , it can be all- star external wiring . All- star wiring to reduce the current transformer secondary load and improve the performance of the current transformer of great benefit .
Its action curve as shown below:
Recommended that the elements of inflection current Ig is set to 1.0 times the rated current of the high-pressure side to ensure the inter-turn short circuit current is less than the rated current of the brake that Ir < when Ie, no braking action .
Differential current threshold criterion should not be too small , it is recommended to take Iqd = (0.3 ~ 0.5) Ie.
Braking coefficient Kcd recommended ratio ranges from 0.3 to 0.7. For dual ring becomes :
In the apparatus , the inflow side of the current transformer are positive direction , the phase difference is corrected automatically by the software . Each side of the current transformer transformers are used in star connection , and to point to the transformer for the same polarity.
2.3 , the second harmonic restraint
The use of three-phase differential current as a criterion in the second harmonic inrush current atresia . Action equation is as follows :
Id2> Kxb · Id
Which is a three-phase differential current Id2 in the second harmonic , Id for the corresponding three-phase differential current , Kxb braking coefficient for the second harmonic . Three-phase differential current in any phase as long as the above conditions are satisfied , all lockout -phase rate differential protection. Kxb generally taken to be between 10% to 30%.
2.4, CT disconnection alarm and lockout
CT has a broken latch or momentary alarm functions and differential current limit alarm function.
2.4.1 , the instantaneous disconnection CT
After starting rate differential , subject to instantaneous disconnection CT testing to ensure the flow is not due to poor break caused . CT is determined after the break , an alarm signal , reporting CT disconnection, by adjusting the control word can decide whether locking differential protection .
CT instantaneous disconnection determined in any of the following conditions is satisfied , the determination is not performed CT disconnection :
1 ) Before starting a side maximum phase current is less than 20% of the rated current side is not sentenced to the side ;
1) After starting the phase current is greater than the maximum of 120% of rated current side ;
1 ) Start served as a side current increase over the previous start.
In the case of the above three conditions are not met, such as one side of the following conditions are satisfied , the penalty for CT disconnection :
1 ) Only one phase current is zero ;
1 ) The remaining two-phase currents are equal before the starting current.
2.4.2 , differential current limit alarm
If the difference is greater than the flow of high-pressure side of the rated current 15 percent , by determining the over 10s, an alarm signal. And reports differential current -limit , but not locking differential protection . This feature and the protective device AC sampling monitoring circuit.
2.5 , cooling failure delayed trip
Tuning control word choice whether to go through the cooling fault protection device tripping delay , the delay time can also be tuning . Cooling failure a high atresia without oil cooling fault contact is closed after the delay time to the trip ; cooling failure 2 by high oil temperature lockout, high oil temperature cooling fault contact and the contact is closed while the delay time to the trip after two way completely independent .
2.6 , non-power protection
From the transformer to the body after WDP230D non- contact power protection devices Verb , outputs a set of blank contacts to SAI-358D main protection device event logging , and MMI will be recorded by the computer to upload to the background . Corresponds WDP230D non-power protection device, choose what information needs to be non-power recorded by a soft cast back plate .
Tuning control word choice whether to go through a cooling fault protection device SAI-358D Main trip delay , the delay time can be tuning . After the delay is reached, the device outputs a paid trip contacts back to the WDP230D non-power protection devices.
2.7 , data record
Function with SAI-318D, analog can be recorded as Iah, Ibh, Ich, Iam, Ibm, Icm, Ial, Ibl, Icl.
2.8 , remote telemetry, remote control
Function with SAI-318D.
Third, the setting and press apparatus
3.1 , setting the value of a list and description of
No. Name setpoint value reference range Symbol Unit Remarks
A control word a KG1 0000 ~ FFFF no see control word description
2 control word two KG2 0000 ~ FFFF no see control word description
3 high-pressure side of the rated current IH 0.2 ~ 15.0 A
4 medium pressure side balance coefficient Km 0.10 ~ 10.00 No
5 low side balance coefficient Kl 0.10 ~ 10.00 No
6 differential speed off current Isd 3Ie ~ 12Ie A
7 differential starting current Iqd 0.2Ie ~ 2Ie A
8 percentage differential inflection current Izd 0.2 ~ 15.0 A
9 ratio differential braking coefficient Kcd 0.20 ~ 1.00 None
10 second harmonic restraint coefficient Kxb 0.00 ~ 1.00 None
11 cooling fault trip delay 1 Tlq1 0 ~ 9000 S High atresia without oil
12 cooling fault trip delay 2 Tlq2 0 ~ 9000 S atresia by high oil temperature
Control word a definition:
Bit is set to 1 meaning set of meanings 0:00
15 CT rated current 1A CT rated current 5A
14-8 Reserved Reserved
7 transformer connection mode selection
6
5
4 Cooling fault trip 2 2 exit into the cooling fault trip
3 cooling fault trip an exit into a cooling fault trip
2 second harmonic restraint into the second harmonic restraint exit
1 CT CT disconnection disconnection locking differential protection is not locking differential protection , only letters
0 differential current limit alarm input differential current limit alarm exit
Transformer Wiring choice
D6 D5 D4 transformer winding way
0 0 0 Y/Y/Y-12
0 0 1 Y / Y / △ -11
0 1 0 Y / Y / △ -1
0 1 1 Y / △ -11 / △ -11
1 0 0 Y / △ -1 / △ -1
101 spare wiring
110 spare wiring
1 1 1 △ / △ / △ -0
3.2 , soft list and description of the platen
Corresponding function name plate
Instantaneous differential differential protection feature cast back
Differential differential protection function cast back
Spare Spare
Heavy gas tripping heavy gas investment return trip
Heavy gas regulator tripping tripping cast back heavy gas regulator
Cooling failure of cooling failure cast back
Pressure relief pressure release cast back
Body light gas light gas tripping tripping body cast back
Light gas regulator tripping tripping cast back light gas regulator
High oil investment return trip tripping high oil
3.3 , setting value calculation methods and procedures
1 ) calculated for each side of the transformer rated current:
In = Sn / ∫ 3Ue
Where : Sn - transformer rated capacity , the unit KVA
Ue - calculation side rated voltage in KV
2 ) calculate the inflow side of the rated secondary current differential elements :
Ie = Kjx × In / Klh
Where : Klh - current transformer ratio
Kjx - Transformer Connection factor. Y side of the transformer ∫ 3, the side of a triangle .
Example : Known transformer parameters
Rated Capacity Sn = 20MVA, each side of the rated voltage 35 ± 4 × 2.5% / 10.5KV, wiring for Y/D-11, optional CT secondary rated current of 5A.
The name of each side numerical
Rated voltage (KV) 35 10.5
Rated Current (A) 20000 / (∫ 3 × 35) = 329.9 20000 / (∫ 3 × 10.5) = 1099.7
CT wiring Y Y
Optional CT ratio 600/ 5 = 1,201,200 / 5 = 240
Setting value twice the rated current (A) ∫ 3 × 329.9/120 = 4.76 1099.7/240 = 4.58
3 ) Start value ratio differential element typically take 30% to 50% of the "high side current rating " given value.
4 ) Current ratio differential inflection generally take 1.0 times the "high side rated current" value .
5 ) the ratio of braking coefficient generally take between 0.3 and 0.7 .
6 ) the second harmonic restraint coefficient is generally desirable between 0.10 to 0.3.
7 ) differential speed off element by escaped transformer inrush current , current imbalance , etc. The most serious failure of the external tuning .
8 ) for non- current side of the balance coefficient is 0 double loop tuning varying .
9 ) computer protection requirements of all connected into each side of the CT Y, phase shift inside the device automatically . Y side of the field windings when connected to an external CT Δ, the device automatically without phase-shifting transformer winding mode setting should be adjusted. Example: Y/Δ-11 double ring becomes connected to the high pressure side of the external CT Δ, the device should be tuning internal wiring is Δ/Δ/Δ-0.
10 ) applied Y/Δ-11 double the volume change, choose Y/Y/Δ-11 or Y/Δ/Δ-11 can , the pressure side is not considered.
Applicable to 110KV and below voltage dual ring, three times the transformer , to meet the requirements of the three sides of the differential . Also applies to generators or - transformer differential protection.
The main protection configuration features :
● differential speed off
● ratio of the second harmonic restraint differential
● CT disconnection locking differential
● cooling fault delay exports
Second, the principle that the protection of
2.1 , the differential speed off
When the current is greater than either move away from the differential speed off the setting value , the total exports of the relay action . Under severe fault conditions for the occurrence of rapid removal of the transformer in the transformer differential area. Should be able to determine the value of the differential speed to escape the maximum inrush current external fault current imbalance and airdrop transformer , and taking into account the current transformer saturation factor , generally take 6 to 12 times the rated current.
Its operating conditions are as follows :
Which is a differential current Id , Isd to determine the value of the differential speed
2.2 , the ratio of the differential
Conventional rate differential principle , its movement equation is as follows :
Id> Iqd Ir ≤ Ig
Id-Iqd> Kcd * (Ir-Ig) Ig <Ir ≤ 2.5Ie
Id-Iqd-Kcd * (3Ie-Ig)> 0.7 (Ir-2.5Ie) Ir> 2.5Ie
Kcd braking coefficient is the ratio
Iqd starting value for the differential current
Differential current Id is Id = | I1 + I2 + I3 |
Ir brake current Ir = 0.5 (| I1 | + | I2 | + | I3 |)
Because each side of the current transformer can be Y / △ adjusted by software , it can be all- star external wiring . All- star wiring to reduce the current transformer secondary load and improve the performance of the current transformer of great benefit .
Its action curve as shown below:
Recommended that the elements of inflection current Ig is set to 1.0 times the rated current of the high-pressure side to ensure the inter-turn short circuit current is less than the rated current of the brake that Ir < when Ie, no braking action .
Differential current threshold criterion should not be too small , it is recommended to take Iqd = (0.3 ~ 0.5) Ie.
Braking coefficient Kcd recommended ratio ranges from 0.3 to 0.7. For dual ring becomes :
In the apparatus , the inflow side of the current transformer are positive direction , the phase difference is corrected automatically by the software . Each side of the current transformer transformers are used in star connection , and to point to the transformer for the same polarity.
2.3 , the second harmonic restraint
The use of three-phase differential current as a criterion in the second harmonic inrush current atresia . Action equation is as follows :
Id2> Kxb · Id
Which is a three-phase differential current Id2 in the second harmonic , Id for the corresponding three-phase differential current , Kxb braking coefficient for the second harmonic . Three-phase differential current in any phase as long as the above conditions are satisfied , all lockout -phase rate differential protection. Kxb generally taken to be between 10% to 30%.
2.4, CT disconnection alarm and lockout
CT has a broken latch or momentary alarm functions and differential current limit alarm function.
2.4.1 , the instantaneous disconnection CT
After starting rate differential , subject to instantaneous disconnection CT testing to ensure the flow is not due to poor break caused . CT is determined after the break , an alarm signal , reporting CT disconnection, by adjusting the control word can decide whether locking differential protection .
CT instantaneous disconnection determined in any of the following conditions is satisfied , the determination is not performed CT disconnection :
1 ) Before starting a side maximum phase current is less than 20% of the rated current side is not sentenced to the side ;
1) After starting the phase current is greater than the maximum of 120% of rated current side ;
1 ) Start served as a side current increase over the previous start.
In the case of the above three conditions are not met, such as one side of the following conditions are satisfied , the penalty for CT disconnection :
1 ) Only one phase current is zero ;
1 ) The remaining two-phase currents are equal before the starting current.
2.4.2 , differential current limit alarm
If the difference is greater than the flow of high-pressure side of the rated current 15 percent , by determining the over 10s, an alarm signal. And reports differential current -limit , but not locking differential protection . This feature and the protective device AC sampling monitoring circuit.
2.5 , cooling failure delayed trip
Tuning control word choice whether to go through the cooling fault protection device tripping delay , the delay time can also be tuning . Cooling failure a high atresia without oil cooling fault contact is closed after the delay time to the trip ; cooling failure 2 by high oil temperature lockout, high oil temperature cooling fault contact and the contact is closed while the delay time to the trip after two way completely independent .
2.6 , non-power protection
From the transformer to the body after WDP230D non- contact power protection devices Verb , outputs a set of blank contacts to SAI-358D main protection device event logging , and MMI will be recorded by the computer to upload to the background . Corresponds WDP230D non-power protection device, choose what information needs to be non-power recorded by a soft cast back plate .
Tuning control word choice whether to go through a cooling fault protection device SAI-358D Main trip delay , the delay time can be tuning . After the delay is reached, the device outputs a paid trip contacts back to the WDP230D non-power protection devices.
2.7 , data record
Function with SAI-318D, analog can be recorded as Iah, Ibh, Ich, Iam, Ibm, Icm, Ial, Ibl, Icl.
2.8 , remote telemetry, remote control
Function with SAI-318D.
Third, the setting and press apparatus
3.1 , setting the value of a list and description of
No. Name setpoint value reference range Symbol Unit Remarks
A control word a KG1 0000 ~ FFFF no see control word description
2 control word two KG2 0000 ~ FFFF no see control word description
3 high-pressure side of the rated current IH 0.2 ~ 15.0 A
4 medium pressure side balance coefficient Km 0.10 ~ 10.00 No
5 low side balance coefficient Kl 0.10 ~ 10.00 No
6 differential speed off current Isd 3Ie ~ 12Ie A
7 differential starting current Iqd 0.2Ie ~ 2Ie A
8 percentage differential inflection current Izd 0.2 ~ 15.0 A
9 ratio differential braking coefficient Kcd 0.20 ~ 1.00 None
10 second harmonic restraint coefficient Kxb 0.00 ~ 1.00 None
11 cooling fault trip delay 1 Tlq1 0 ~ 9000 S High atresia without oil
12 cooling fault trip delay 2 Tlq2 0 ~ 9000 S atresia by high oil temperature
Control word a definition:
Bit is set to 1 meaning set of meanings 0:00
15 CT rated current 1A CT rated current 5A
14-8 Reserved Reserved
7 transformer connection mode selection
6
5
4 Cooling fault trip 2 2 exit into the cooling fault trip
3 cooling fault trip an exit into a cooling fault trip
2 second harmonic restraint into the second harmonic restraint exit
1 CT CT disconnection disconnection locking differential protection is not locking differential protection , only letters
0 differential current limit alarm input differential current limit alarm exit
Transformer Wiring choice
D6 D5 D4 transformer winding way
0 0 0 Y/Y/Y-12
0 0 1 Y / Y / △ -11
0 1 0 Y / Y / △ -1
0 1 1 Y / △ -11 / △ -11
1 0 0 Y / △ -1 / △ -1
101 spare wiring
110 spare wiring
1 1 1 △ / △ / △ -0
3.2 , soft list and description of the platen
Corresponding function name plate
Instantaneous differential differential protection feature cast back
Differential differential protection function cast back
Spare Spare
Heavy gas tripping heavy gas investment return trip
Heavy gas regulator tripping tripping cast back heavy gas regulator
Cooling failure of cooling failure cast back
Pressure relief pressure release cast back
Body light gas light gas tripping tripping body cast back
Light gas regulator tripping tripping cast back light gas regulator
High oil investment return trip tripping high oil
3.3 , setting value calculation methods and procedures
1 ) calculated for each side of the transformer rated current:
In = Sn / ∫ 3Ue
Where : Sn - transformer rated capacity , the unit KVA
Ue - calculation side rated voltage in KV
2 ) calculate the inflow side of the rated secondary current differential elements :
Ie = Kjx × In / Klh
Where : Klh - current transformer ratio
Kjx - Transformer Connection factor. Y side of the transformer ∫ 3, the side of a triangle .
Example : Known transformer parameters
Rated Capacity Sn = 20MVA, each side of the rated voltage 35 ± 4 × 2.5% / 10.5KV, wiring for Y/D-11, optional CT secondary rated current of 5A.
The name of each side numerical
Rated voltage (KV) 35 10.5
Rated Current (A) 20000 / (∫ 3 × 35) = 329.9 20000 / (∫ 3 × 10.5) = 1099.7
CT wiring Y Y
Optional CT ratio 600/ 5 = 1,201,200 / 5 = 240
Setting value twice the rated current (A) ∫ 3 × 329.9/120 = 4.76 1099.7/240 = 4.58
3 ) Start value ratio differential element typically take 30% to 50% of the "high side current rating " given value.
4 ) Current ratio differential inflection generally take 1.0 times the "high side rated current" value .
5 ) the ratio of braking coefficient generally take between 0.3 and 0.7 .
6 ) the second harmonic restraint coefficient is generally desirable between 0.10 to 0.3.
7 ) differential speed off element by escaped transformer inrush current , current imbalance , etc. The most serious failure of the external tuning .
8 ) for non- current side of the balance coefficient is 0 double loop tuning varying .
9 ) computer protection requirements of all connected into each side of the CT Y, phase shift inside the device automatically . Y side of the field windings when connected to an external CT Δ, the device automatically without phase-shifting transformer winding mode setting should be adjusted. Example: Y/Δ-11 double ring becomes connected to the high pressure side of the external CT Δ, the device should be tuning internal wiring is Δ/Δ/Δ-0.
10 ) applied Y/Δ-11 double the volume change, choose Y/Y/Δ-11 or Y/Δ/Δ-11 can , the pressure side is not considered.
