Guodian Nanzi PSL641UX Line Protection Measurement and Control Device
2 Protection function and principle
2.1 Phase to phase overcurrent protection
When the device executes the three section overcurrent discrimination, the discrimination logic of each section is consistent, and the action conditions are as follows:
1） I? ＞ Idn; Idn is the current setting of section n, and I? Is the phase current;
2） T ＞ Tdn ； Tdn is the n-segment delay setting.
2.1.1 Interphase directional element
90? Wiring mode: start according to phase. With the current flowing out of the bus as the positive direction, the action range Arg (U/I) ＝－ 90? ～ ＋ 30?， error
Poor ＜? 5?。
2.1.2 Low voltage locking element
The low-voltage element acts when any of the three line voltages is lower than the low-voltage fixed value, and the locked protection element is disclosed. With this element,
It can ensure that the device is Motor No misoperation occurs under non fault conditions such as feedback.
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2.1.3 Negative sequence overvoltage locking element
When the negative sequence voltage is greater than the fixed value, the locked protection element is disclosed. This element, together with the low-voltage locking element, forms a composite voltage locking element,
It forms compound voltage overcurrent protection with overcurrent components.
2.2 Phase to phase current inverse time element
The inverse time protection element is a protection element whose action time limit naturally matches with the current in the protected line. By translating the action curve
It is very convenient to realize the cooperation of the whole line. The device provides three common inverse time characteristics, namely standard inverse time, very inverse time and extreme inverse time.
The inverse time characteristic is set by the "inverse time index" in the fixed value. The formula of each inverse time characteristic is as follows:
1) General inverse time limit
2) Very inverse time limit
3) Extreme inverse time limit
Where tp is the time coefficient, ranging from 0.05 to 1; Ip is the current reference value; I is fault current; T is the tripping time.
The inverse time limit of the setting value is the product of the numerator in the above expression, in seconds, and the setting range is (0.005~127).
It can also be realized for long time inverse time limit. The expression of long time inverse time limit is as follows:
For the interphase current protection of the device, the definite time limit or inverse time limit can be selected by setting the relevant bits of the control word. When the inverse time limit mode is selected,
Automatically exit the fixed time limit section III overcurrent protection, and the function platens of the interphase current section III become the interphase current inverse time limit function enable/disable platens respectively.
2.3 Zero sequence overcurrent
When the zero sequence current is used as tripping or alarm, the zero sequence current can be selected from the outside by KG1.7 bit of control word 1 in the operation parameter
The special zero sequence CT is introduced or generated by the software itself, and the device defaults to the external connection of zero sequence current.
The outlet of zero sequence overcurrent protection trips when the following conditions are met:
1) 3I0>I0n, I0n is the fixed value of grounding section n;
2) T>T0n, T0n is the fixed value of grounding n-section delay;
3) The corresponding direction conditions are met (if necessary).
2.3.1 Zero sequence directional element
The zero sequence current is in the positive direction of the bus flow to the line, and the zero sequence TA polarity terminal is connected to the 3I0 polarity terminal of the device. Connect as per the primary system neutral point low resistance
For local consideration, the action area of zero sequence directional element is set as Arg (3U0/3I0)=－ 195? ～ － 75?。 3U0 is self-produced.
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When the neutral point of the primary system is grounded with medium resistance or high resistance, the action area can be adjusted according to the different conditions of the system. book
Special instructions shall be given at the time of shipment.
2.3.2 Zero sequence inverse time element
The principle of zero sequence inverse time element is the same phase overcurrent inverse time element, and the inverse time characteristic is set by the inverse time index in the setting value.
The zero sequence overcurrent protection of the device can select the definite time limit or inverse time limit mode by setting the relevant control word. When inverse time limit mode is selected, automatic
Exit the zero sequence overcurrent element of section II, and the functional pressing plate of zero sequence overcurrent section II will be changed into the enabling/disenabling pressing plate of zero sequence overcurrent inverse time limit function.
2.3.3 Zero sequence current alarm element
The zero sequence current will send an alarm signal after meeting the setting value of "zero sequence overcurrent alarm" and setting value of delay time.
2.4 Closing acceleration
It includes manual acceleration and protection acceleration. The acceleration function can be enabled or disabled through the soft pressing plate.
The starting conditions of the manual acceleration circuit are:
1) The time of the circuit breaker in the opening position exceeds 30s;
2) The circuit breaker changes from opening to closing, and the acceleration function is open for 3s.
Manual acceleration requires input of acceleration strap, setting of acceleration current and time settings, and the acceleration mode can be realized by selecting the post acceleration mode from the control word
This function is now available. The manual acceleration protection function is put into operation separately, which can be used for charging protection of sectionalized or bus tie circuit breaker.
The protection acceleration is divided into front acceleration or post reclosing acceleration, and one of them can be selected by the control word.
The protection is set with separate overcurrent and zero current acceleration section current settings and corresponding time settings, which makes the protection configuration more
Flexibility. The overcurrent acceleration section of this protection can also select low-voltage locking and negative sequence voltage locking, but direction locking is not considered for all acceleration sections.
2.5 Three phase reclosing
It has three-phase primary reclosing and secondary reclosing functions. Enable/disenable the function by the corresponding soft strap, and enable II when the control word KG2.11=1
Secondary reclosing function.
2.5.1 Charging conditions
The circuit breaker is closed, TWJ=0, HWJ=1, and there is no locking reclosing signal. Reclosing charging is completed after 15s. Reclosing during charging
Soft platen lamp Flash, flat light after charging, no longer blinking.
2.5.2 Startup mode
After reclosing charging is completed, reclosing can be started by two ways: protection startup and non corresponding startup.
The protection startup reclosing is a protection action. After judging the breaker position and no current, open the reclosing for 10s.
In the non corresponding start reclosing mode, only TWJ contacts are used to monitor the position of the circuit breaker.
2.5.3 Reclosing mode
The reclosing mode can be selected through the setting of "Synchronizing mode selection": no inspection mode, no voltage inspection mode, synchronous inspection mode, no voltage inspection mode
Period method.
In the no voltage detection mode, when the control word KG2.9=0, the line extraction voltage is less than 0.3 times the rated voltage, it is judged as no voltage. Current control word KG2.9
When=1, the bus is free of voltage or the line extraction voltage is less than 0.3 times the rated voltage. If KG2.6 ＝ 1, the rated voltage is 100V; back
57.7V.
When checking the synchronization, the phase of the line extraction voltage is set by the setting value "Selection of phase of synchronization". When bus voltage and line extraction voltage are both greater than 0.75
When times the rated voltage, check the phase difference between the line extraction voltage and the bus voltage of the corresponding phase. If it is less than the set synchronization angle, check
The synchronous conditions are met. Among them, the selection of rated voltage is the same as that of voltage free mode
