What is neutral current?
Neutral Current: The current measured on the neutral cable in a normal three-phase four-wire or three-phase five-wire power cable is referred to as neutral current.
The generation of neutral current: The main reasons for the generation of neutral current in a three-phase four-wire or three-phase five-wire power supply network are:① Unbalanced neutral current caused by unbalanced three-phase current, ② Neutral current generated by the three-phase superposition of zero-sequence harmonics on the lighting load side flowing into the neutral wire (the excessive neutral current in today's three-phase four-wire or three-phase five-wire power supply is mainly due to the zero-sequence harmonics flowing into the neutral wire).
2、Definition and Characteristics of the Order Harmonic
Zero-sequence harmonics in an electrical power system are harmonics of current or voltage with the same direction as the three-phase current or voltage vectors.3 times, 6 times, 9 times, and 3n (where n=1, 2, 3)…The composition of the harmonic current is the 3rd harmonic current. Since it typically flows into the neutral line, in a three-phase balanced four-wire power system, the neutral line current is the zero-sequence harmonic current.
3. Neutral Line CurrentThe dangers:
During circuit design, it's common for the neutral wire to be much thinner than the phase wire. High currents flowing into the neutral wire exacerbate the following issues.
(1) Severe overloading of the neutral line causes overheating of the cables and wires, accelerating the aging of the insulation.
(2) Insulation aging to a certain degree can lead to short circuits and grounding faults, causing electrical fires.
(3) Zero-sequence current causes cable heating, metal sheath heating, transformer heating, and increased energy consumption.
(4) Neutral line zero drift, causing the neutral line to have voltage to the ground, posing a potential hazard to equipment and personal safety. Interference with low-voltage equipment (such as computer crashes, malfunctioning instruments, and inaccurate electrical meter readings).
(5) Zero-sequence harmonics often lead to low transformer utilization and excessive loading on the neutral line, causing frequent tripping.
4、Litetech Standard Type ZeroLine Current Eliminator
Leitai Energy Smart Standard Type ZeroLine Current EliminatorA new neutral wire current eliminator co-developed by the Shenzhen Liewu Power Quality and Power Engineering Expert Group of universities and colleges, primarily suitable for loads with balanced three-phase current.15%Eliminate neutral current within the range, Neutral current elimination90%Above.
4.1、Applicable Venue
Office buildingLED screens, street lamps, shopping malls, banks, medical use, scientific research, schools, sports venues, studios, etc., with models 3,6、9、15Dominant are the 2nd and 3rd harmonic components.
4.2Performance Features
l Significantly reduces the current in the neutral wire, eliminating fire hazards caused by excessive neutral wire current.
l Can simultaneously filter out3、6、9、12、15Harmonic 2Current；
l No filter capacitors or electronic components, with high reliability like a dry-type transformer, lifespan up to twenty years.
l Effectively avoids harmonic amplification.
l Avoid harmonics interference with precision equipment (such as computer crashes), which can lead to unnecessary losses.
l Effectively protects capacitors from overload due to reactive compensation, extending their service life.
l Effectively reduce the iron and copper losses of transformers, energy-saving3-10%+
l Increase transformer utilization rate (due to excessive neutral current, some transformers have insufficient utilization)30%）；
Avoid false operation of zero-sequence protection and eliminate economic losses caused by such false operations.
5、Technical Data
The technical data listed in this table is for common specifications. For any special requirements, please contact us.
Work Conditions | Relative Humidity: 90%RH High environmental temperature:40℃ High Altitude:2000m |
Basic Electrical Parameters | Rated Frequency:50Hz Rated Voltage:400V Overall Equipment Effectiveness: ＜3W/KVA |
Connection Method | Three-phase four-wire system, cables or copper busbars connected |
Insulation Grade | H Grade (B Grade under normal operating conditions) |
Protection Class | IP30 |
Standard of Execution | GB/T14549-1993、GB10941-1996、GB19212.1-2003、GB6450-1986、 GB/T501-1991 |
6Installation Method
7、Litetech Standard Type ZeroLine Current EliminatorSelection Chart
