PLB-II Overcurrent and Overvoltage Protector Manual
I. Overview
In traditional power station protection systems, relay-type protection devices are often used for generator overcurrent and overvoltage protection. Such devices generally have the disadvantages of low accuracy, poor stability and reliability, and cumbersome installation.
Yongyuan PLB-II generator overcurrent and overvoltage protector is an intelligent control and protection device specially developed and designed for the problems of relay protection. It takes an eight-bit microprocessor as the core and uses precise control algorithms to make the device have excellent control performance and control accuracy.
This device integrates overcurrent, overvoltage and undervoltage protection in one. It can completely replace the traditional protection mode of multiple relays, simplifying the installation process and improving reliability. The device can display the generator voltage and current value in real time, which is easy to observe and operate; its operation is very convenient and can be applied to the transformation of small and medium power stations and old power stations. It can greatly improve the reliability and safety of generator protection, and it is also useful for improving power station The level of automation is also positive.
2. Technical indicators:
2.1 Scope of application: various medium and small high-voltage and low-voltage generator sets
2.2 Input signal:
2.2.1 PT voltage:
2.2.1.A. Nominal 100V generator PT voltage transformer voltage
2.2.1.B. Nominal 230V generator phase voltage
2.2.1.C. Nominal 400V generator line voltage
2.3. Three-phase current: nominal 5A generator three-phase CT (current transformer) current signal
(Note that the end of the same name is on the same side of the CT linear range 0-7A)
2.3. Output signal:
Relay switch signal (with two ways of normally open and normally closed)
Relay contact capacity AC 220V/5A 380V/2A
DC 110V/0.8A 220V/0.2A
2.4. Voltage measurement accuracy: 1%;
2.5. Current measurement accuracy: 1%;
2.6. Power supply:
AC 140VAC~285VAC
DC 140VDC-400VDC
2.7. Power consumption: less than 6W
2.8. Working environment:
Ambient temperature -5~+50ºC
Relative humidity is not more than 90% (40ºC)
Areas below 2000 meters above sea level
2.9. Dimensions: length × width × depth = 120 × 120 × 130
3. Main functions
3.1. Overvoltage protection:
When the protector is running, when the generator voltage is continuously higher than the set overvoltage protection value for a certain period of time (this time can be set), the protector will act. An intermittent buzzer alarm is issued, (can be cancelled with the plus and minus keys) the panel red fault light is on, and the digital tube display automatically switches back to the voltage value display state to display the voltage value at this time in real time, and the fault protection relay operates to send a trip signal to cut off the generator Voltage output (on-grid closing is not allowed before grid-connection). After the delay is set for a period of time, the instrument starts to judge whether the generator voltage is normal. If the generator voltage returns to normal, it will automatically release the trip signal and exit the fault state, otherwise it will remain in the protection state. You can also exit the fault state in advance through manual intervention by pressing the "Settings" key.
3.2. Undervoltage protection:
Before the generator is connected to the grid, when the generator voltage is lower than the set under-voltage protection value, the protector is in a fault protection alarm state, and grid-connected closing is not allowed. After the generator voltage returns to normal, the protector automatically exits the fault protection state. The undervoltage protection function can be turned off by parameter setting.
3.3. Overcurrent protection:
When any one of the three-phase current of the generator is continuously greater than the set overcurrent protection value for a certain period of time (this time can be set) during grid-connected operation, the protector enters a fault alarm state and sends a trip signal. At this time, the digital tube display automatically switches back to the current value display state, and locks the current value at the moment of tripping. After a set period of delay, the trip signal is automatically released and the fault state is exited. It is also possible to exit the fault state in advance through manual intervention by pressing the "Settings" key. Overcurrent protection is an inverse time limit control method. Based on the set overcurrent delay trip time, the protector automatically modifies the overcurrent delay trip time according to the degree of overcurrent. The greater the overcurrent, the faster the protection action.
When the protection trip occurs, the fault should be eliminated according to the actual situation in time, otherwise the protection will trip again due to the continued existence of the fault after the protection is automatically restored. Over-current, over-voltage delay protection and recovery time can be set by parameters and set according to actual needs. This can avoid frequent protection trips due to short-term over-current or over-voltage, thereby improving the stability of the entire system and avoiding unnecessary staff stress. At the same time, through the real-time digital display of the current and voltage values of the protector panel, the current and voltage data can be grasped in time and accurately, so that various situations can be quickly and accurately judged. These are advantages that the relay type protection device does not have.
3.4. E2PROM data protection:
The instrument adopts E2PROM data protection when power off. All the parameters and working status of the initial settings will not be lost due to sudden power failure and can be stored permanently.
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