the protection device consists of the completed two or three winding main transformer protection with the 9692,9693 main transformer differential protection device,the 982 main transformer medium-voltage side backup protection measuring and control device,the 9683 main transformer low Voltage side backup protection measuring and control device,the 984 main transformer backup operating gear,the 985 main transformer non-electric quantity protection,
function of protection relay
Over current instantaneous trip（trip segmentation）, with low voltage lockout,negative sequence voltage lockout.
time delay over current instantaneous trip（all the breakers in the main transformer trip）, with low voltage lockout,negative sequence voltage lockout.
The Over current instantaneous trip and time delay over current instantaneous trip can be choose,interphase direction selection.
time delay current instantaneous trip （time delay current instantaneous trip ,direction of the time delay current instantaneous trip,low voltage lockout）；
zero sequence over current（zero sequence over current,Zero sequence voltage lockout、zero sequence trip、Zero sequence direction selection).
Clearance zero sequence protection,
PT no voltage（alarm）,
busbar grounding （alarm）,
pressure anomaly （SF6 Low pressure alarm）,
Measuring and control
busbar voltage ：Uab、Ubc、Uca；Ua、Ub、Uc；
measuring cuttent ：Ia、 Ib、 Ic、
control circuit break,
Manual closing and switch in
remote closing and switch in.
Optical fiber communication.
Protective action principle
① time delay current instantaneous trip protection
1．RLP1 time delay current instantaneous trip protection－in service
2．Protective current IA（IB）IC any one sampling value≧ the fix value of time delay current instantaneous trip protection（Idz3）
3．Time of the current≧time delay current instantaneous trip protection tzd3
Protect immediate output C7/C8、C9/C10、C11/C12,at the same time the 同时驱动accident signal relay drive C1/C3（return after 10s ）,Panel accident light
② I—II segment Combined voltage blocking over current protection
The device is set with three segment composite voltage blocking over current protection.Three section protection and time setting value can be set separately,According to the actual situation, we can choose the compound voltage or the compound voltage to start over current protection.In order to prevent the decrease of the PT line-break or the PT voltage , the protection will automatically withdraw from the negative sequence voltage and low voltage when the alarm signal occurs.
（1）．Zero sequence current instantaneous trip protection （Delayed time trip C15/C16）
（2）．Zero sequence time delay current instantaneous trip （Delayed jump trip the sideC7/C8）
（3）．Zero-Sequence definite time over-current （Delayed trip, trip to the side, the side of the trip C7/C8、C9/C10、C11/C12）
（4）．Low voltage blocking over current； （Need to put "over current" protection at the same time，and no PT line-break,no PT loss voltage）
the low voltage judge by Uca Line voltage， the current is greater than the set value at a certain phase,Uca line voltage is less than the set value（General low voltage set value is 70V）,then protection will be able to move，It is mainly used for the discrimination of voltage symmetrical short circuit, and the negative sequence voltage；
（5）．Negative sequence voltage lockout over-current; (need and put into "over current protection and a continuous line of PT without losing pressure) negative sequence voltage is mainly used for voltage asymmetric short circuit, in a phase current protection is greater than the set value, the negative sequence voltage greater than set value (usually negative sequence voltage setting for 7V) protection will be act.
Description: at the same time put into the "over current, low voltage blocking over current, negative sequence voltage blocking off flow", can reduce the current transient error, and can guarantee the voltage in the symmetrical short circuit and asymmetric short circuit protection action.
③ Clearance zero sequence overcurrent protection
1．RLP12 Clearance zero sequence－in service
2．Gap zero sequence current Ioj sampling value ≧Clearance over current fixed value（Ijdz1）
3．Time of Zero sequence current ≧Clearance over current delay tjzd1
Protect immediate exit C7/C8、C9/C10、C11/C12，Simultaneous drive accident signal relay C1/C3（Return after 10s）,Panel accident light.
④ Over load
1．RLP9 Over load－in service；
2．Protection current IA（IB）IC anyone sampling value≧ Over load fixed value（Idz4）
3．Time of current≧Overload delay tzd4
Protection immediately driving alarm signal relay C2/C3（return after 10s）.Panel warning light.
Description: if over load needs on - load voltage regulation (the low backup is open the fan over load, the same as following), you need to
Description: over load if you need to lock the load voltage adjustment (low backup is over load open the fan, with the next), you need to
1．RLP17 Overload alarm －in service
2．RLP18 Over load on- load voltage regulation－in service
3．Protection current IA（IB）IC Any phase sampling value≧ Over load fixed value（Idz4）
4．Time of current≧Overload delay tzd4
Protect immediate exitC17/C18，Simultaneous drive accident signal relay C1/C3（Return after 10s).The panel warning light is on.
⑤ Zero sequence overcurrent
1．RLP8 Zero sequence overcurrent－in service
2．Zero sequence current 3Io sampling value≧ Zero sequence over current fixed value（Iodz）
3．After a period of delay（Exit C15/C16）、The two section(export C7/C8、C9/C10、C11/C12）、 three-section （Exit C7/C8、C9/C10、C11/C12）
Protection immediate exit, while driving accident signal relay C1/C3（Return after 10s）.Panel accident light.
⑥ Zero sequence over-voltage
1．RLP11 Zero sequence over-voltage－in service
2．Zero sequence voltage 3Uo sampling value ≧ Zero sequence overvoltage（Uodz2）
3．After delay T0zd4
Protect immediate exit C7/C8、C9/C10、C11/C12，Simultaneous drive accident signal relay C1/C3（Return after 10s）.Panel accident light
⑦ control circuit break
1．RLP7 control circuit break－in service
2．Protection device control circuit break time≧Control loop delay（Tdz3）；
Protection immediately driving alarm signal relay C2/C3（Return after 10s）.Panel warning light
Description: the control loop is broken.：
If the switch is in the position of the closing status, the information of the control loop is broken, the trip coil circuit is disconnected.；
If the switch in a state of breaking, send out the "control loop break" information, then the closing coil circuit disconnect