In the power system, ferromagnetic resonance occurs frequently, and overvoltage occurs during resonance, which seriously threatens the safety of the system. Ferromagnetic resonance overvoltage can occur in any system from 3 to 220 kV, especially in power grids of 35 kV and below, almost all internal overvoltage accidents are caused by ferromagnetic resonance. The overvoltage caused by ferromagnetic resonance is long-lasting and may even exist for a long time. In the frequency division resonance, the general overvoltage is not high, but the current of the PT is large, which is easy to cause the PT to overheat and explode; in the fundamental wave and frequency multiplication resonance, the general current is not large, but the overvoltage is very high, which often damages the equipment insulation. , causing a serious accident.
The power microcomputer harmonic elimination device is a new type of intelligent power resonance elimination device developed by our company. It is simple and convenient to use, requires no maintenance, can quickly eliminate ferromagnetic resonance of various frequencies, and has high accuracy. At the same time, the relevant information can be printed or transmitted to the superior monitoring system through the communication interface according to the user’s needs, which is suitable for unattended substations.


●Modular design, compact structure, advanced technology, high-speed 32-bit ARM core processor ensures real-time operation and action accuracy.
●Real-time monitoring of system status, real-time calculation, accurate judgment of low-frequency, fundamental frequency, high-frequency resonance faults in the system, and timely action.
●Real-time display of three-phase voltage, opening voltage, can accurately determine grounding, overvoltage and undervoltage, resonance.
●If the resonance of the system is eliminated by damping, if it is excited again, the device can be restarted immediately to eliminate it.
●Industry standard RS-485 communication interface, can transmit the running status of the system to the upper computer in real time.
●Fault recall function, large-capacity Flash memory saves the last 30 historical fault records.
●With good electromagnetic compatibility, it is suitable for application in complex environment with strong electromagnetic interference.
●Dual hardware watchdog circuit ensures the reliability of software operation.
●Chinese LCD display, clear running status, menu-based operation, easy to use.

A	illustrate
A1	AC/DC
A2	AC/D
A3	PT opening*
A4	PT opening
A5	Alarm public terminal
A6	Earth alarm
A7	Over/under voltage alarm
A8	Resonance alarm
A9	Fault alarm
A10	Device shielding ground
A11	485A
A12	485B
A13	GND
A14	Alternate
A15	Alternate
A16	Alternate
A17	Neutral point O
A18	A phase voltage input
A19	B phase voltage input
A20	C phase voltage input

product name	product model	basic function		remarks
Microcomputer harmonic device	NLK-XX Microcomputer harmonic device		Monitor the status of the system in real time, and make an accurate judgment of the low frequency, base frequency and high vibration faults of the system. If the system resonance is eliminated by damping, the device can start again to provide the RS interface of three-phase voltage measurement overvoltage undervoltage grounding P break with a bus (+ 50 yuan)	Open hole is 178mm * 128mm