Study on several protection logic of FTU

2. Three-stage current protection

   Three-stage fixed time overcurrent protection each section action current fixed value and the action time fixed value can be independently set, each section overcurrent protection uses the same action discrimination logic, the action export condition is:

   1. For the nth segment of the current set value
   2. Three-stage protection input
   3. Delay Time to

   Three-stage protection soft platen input, three-phase current maximum value is greater than IdZ (set N-segment overcurrent), Time delay T1 (n-segment overcurrent delay time), three-stage fixed value protection action, equipment upload event, display fault, record event, according to the Overcurrent fault action soft platen is put into execution tripping action.

4. Post-acceleration protection

   In the manual closing and over-current acceleration protection process, in order to make the reclosing normal operation and ensure that the system will not be coincident with the fault for a long time, it is possible to use this function, over-current accelerated selection after acceleration mode, that is, after the reclosing of the Acceleration section protection logic discrimination, accelerating the protection of the action conditions:

   1. Post-accelerated protection of soft platen input
   2. The switch is switched from the gate to the closing
   3. After the overcurrent type reclosing or the pressure-loss reclosing, the pre-setting value of any current in the line exceeding the protection of the accelerating section is detected in the post-accelerated opening time Ijs, and after the delay TJs is reached, the switching action

   Note: TJs is the time setting value for the accelerated segment protection, which is different from the post-accelerated opening time, which refers to the time period of the over-flow acceleration period.

   Post-accelerated latching closing (no closing action) action conditions are:

   (1) Locking and closing control soft platen after input over-current accelerating action

   (2) Accelerated action after flow, and no return signal

   Operating conditions to meet the lockout remote control, pressure mismatch, contact closing, three times reclosing, but does not lock the external circuit manual closing.

   0 sequence current after the acceleration action conditions are:

   1. Accelerated fixed value after 0 sequence current is greater than 0 sequence current
   2. Delay Time to
6. Three-stage 0-sequence overcurrent protection

   0 Sequence Current protection soft platen input, when the detection of the three-phase synthesis 0 sequence current I0 greater than the setting of the 0 sequence current protection fixed value i0dz, and to achieve the set delay time T2, the terminal tripping action, data on the hair, fault display and event recording, according to the control output soft platen input Select trip or alarm.

8. 0 Sequential Overvoltage Protection

   The same 3. The protection mechanism of three-stage 0-sequence overcurrent protection is consistent.

10. Loss-of-pressure split gate protection

    The operating conditions for the protection of the pressure-loss brake are:

    1. Protection of soft platen with pressure-loss divider
    2. Switch in the closing position
    3. Pressure on both sides of the switch, i.e. min (UA1,UB1,UC1) >uh (with pressure setting) or min (UA2,UB2,UC2) >uh on the switch when combined, with a duration greater than T3 (with pressure delay time)
    4. Terminal pressure loss, both sides of the switch voltage is less than UL (line no pressure setting value)
    5. Terminal no flow, switching circuit current less than IL (line with flow setting value)
    6. Delay time greater than T4 (loss-of-voltage protection delay setting value)

    To meet the protection of the upper conditions, according to the control output soft platen is put into the choice of tripping or alarm.

12. Pressure-loss reclosing protection

    After the circuit switch performs the out-of-voltage protection action, the fail-safe recloser protection can be performed with the following conditions:

    1. Input pressure-loss reclosing protection and protection plate
    2. Reclosing not latching
    3. Switch in the position of the gate (from close to divided)
    4. Within the T5 of the pressure-loss coincident opening time (for a period of time after the loss-of-pressure protection action)
    5. One side voltage is greater than the pressure setting value uh, the side voltage is less than the non-pressure setting value UL
    6. After the T6 of the pressure-loss coincident time is reached

    The terminal performs a voltage-loss coincident action, recording events and uploading data.

14. Over-current reclosing protection

    Overcurrent type reclosing protection in the case of two loops, the conditions for reclosing execution are:

    1. Over-flow three-stage action
    2. One side voltage is greater than the pressure setting value uh, the side voltage is less than the non-pressure setting value UL
    3. Within T5 of the reclosing Opening time (after a period of time after the Overcurrent protection action, this value is consistent with the reclosing opening time T5 in the reclosing coincidence
    4. Closing not latching
    5. Over-current coincident soft platen input
    6. The switch is in the split gate position

    If it is a single-loop case, it is not necessary to determine whether one side of the voltage pressure, the other side is not pressure this situation.

16. Contact switch out-of-voltage self-cast protection

    In hand-held ring network distribution network contact point of the contact switch, the loss of self-investment protection logic input, the normal operation of the switch is in the position of the gate, the first to ensure that the switch on both sides have pressure, that is, the meaning of the first two & relationship, the pressure time should exceed the pressure delay time; self-cast protection execution

    1. Contact switch pressure-loss self-cast protection soft platen input
    2. The switch is in the split gate position
    3. Pressure on both sides of the switch (voltage greater than uh, and continuous T3 with pressure delay time)
    4. Pressure on one side (>uh with pressure setting), one side without pressure (<ul no pressure setting value)
    5. Closing is not in latching state
    6. Loss of pressure self-cast open time T8 detection of the pressure on the side of the pressure or instantaneous pressure, then the protection reverts, and closed closing
18. Pressure lockout self-cast protection logic on both sides of the contact switch

    The voltage lockout self-cast protection logic performs the following conditions:

    1. The contact switch is in the split gate state
    2. On both sides of the pressure locking self-cast protection logic soft platen input
    3. The line voltage is greater than the "bus has a voltage setting value Uh"
    4. Closed-loop operation Logic is not engaged
    5. Delay T10 time (both sides have pressure lockout self-cast protection delay setting value)

    When the above conditions are established, closed automatic closing, remote control closing, device panel closing.

20. Closed-loop Operation Protection logic

    Line contact switch, after the protection input of the ring operation, the logic execution condition is:

    1. The line voltage is greater than the "bus has a voltage setting value uh"
    2. The difference between UA1 and Ua2,ub1 and UB2,UC1 and UC2 is less than the pre-set "closed-loop differential pressure setting"
    3. Closed-loop operation Protection Soft platen input

    The above conditions are satisfied, then automatically unlock the "contact switch on both sides of the pressure lockout closing" protection logic, you can perform manual closing.

22. Momentary pressure latching closing protection logic

    When the switch in the circuit performs the protection of the voltage-loss or the over-current, the circuit breaker is in the position of the split gate, the logic input of the instantaneous voltage lockout and the logic execution condition is:

    1. Instantaneous pressure detection time period T11, the line voltage is greater than the pre-set "instantaneous pressure fixed value ut" After the loss of pressure
    2. The circuit breaker is in the split gate position
    3. The input of the soft platen of the instantaneous pressure latching closing protection

    When the above conditions are met, the controller performs latching automatic closing logic, and the circuit breaker is automatically unlocked after manual closing.

24. Protection logic for latching split gate

    Line switch lockout protection logic input, after the line switch is performed to press the coincident or over-current coincident action, the switch is in the closing position, in the "latch-up gate detection T12" not detected in the three-phase protection, transient voltage protection, acceleration section protection action and line loss, controller lockout automatic separation gate, delay "reversion time T13 after "is automatically unlocked, so the logical execution condition is:

    1. Locking and switching protection logic soft platen input
    2. The switch is in the closing position
    3. Over-current three-stage protection, transient voltage protection, accelerated section protection, and line pressure loss

    The above conditions are satisfied, the controller is locked automatically, and the delay T13 automatically unlocks the protection.

26. Latching Closing protection logic

    Line switch lockout protection logic input, after the line switch to perform a pressure-type coincidence or over-flow type coincident action, in the "closed-off detection time T14" detected over-current three-stage protection, transient voltage protection, acceleration section protection action and line loss of voltage protection occurs, the controller lockout automatic closing, The circuit breaker is automatically unlocked after manual closing, the specific logic execution conditions are:

    1. The switch is in the closing position
    2. Over-current three-stage protection, transient voltage protection, accelerated section protection, and line pressure loss
    3. Protection occurs in "latching closing detection time T14"
    4. Locking and closing protection soft platen input

    The above conditions meet, the controller latch automatic closing, after the circuit breaker manual closing automatically unlocked.

Study on several protection logic of FTU