What is neutral current?

Neutral Current: The current measured on the neutral cable in a standard 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 Zero-sequence harmonic current flowing into the neutral line due to the superposition of three-phase harmonics on the lighting load side (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 line).

2、Definition and Characteristics of Harmonic Series

Zero-sequence harmonics in an electrical system are harmonics that have the same direction as the three-phase current or voltage vectors, originating from...3, 6, 9, and 3n (where n = 1, 2, 3)…The composition of harmonic currents. Since it usually flows into the neutral wire, in a three-phase balanced four-wire power system, the neutral wire current is the zero-sequence harmonic current.

3. Neutral wire currentHarmfulness:

During circuit design, the neutral wire is typically much thinner than the phase wire, with large currents flowing into the neutral wire, making the following issues more prominent.

(1) Severe overloading of the neutral line, causing overheating of cables and wires, accelerates insulation aging.

(2) Insulation aging to a certain extent can lead to short circuits and ground faults, causing electrical fires.

(3) Zero-sequence current causes cable heating, metallic sheath heating, transformer heating, and increased energy consumption.                             

(4) Neutral line zero drift causes the neutral line to have voltage to the ground, posing potential hazards 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.

4Lift Unequal Balancing Type ZeroLine Current Eliminator

    Leiter Unbalanced Adjustment ZeroLine Current EliminatorIt is a novel neutral wire current eliminator jointly developed by the power quality group at Shenzhen Liwu Power and large and medium-sized universities. This device is primarily suitable for load with three-phase current balance.0-99%Zero-line current elimination within range90%Above.

4.1、Technical Differences Between Current Imbalance Compensation Type and Standard Type Neutral Wire Current Eliminators

1、Three-phase voltage will not vary with the change in current.        

2. Three-phase output phase voltageEnterPhase voltage difference between phases does not exceed 3V。

3. Compliant with National Standard for Power Quality Three-phase voltage allows imbalance degree <2% Requirements;

4.2、Applicable Locations

Office buildingLED Displays, street lights, shopping malls, banks, medical, research, schools, sports venues, studios, etc., with a range of 3,6、9、15The main component is the 2nd harmonic.

4.3Performance Features

l Significantly reduces current in the neutral wire, eliminating fire hazards caused by excessive neutral wire current.

l Can simultaneously filter out3、6、9、12、15Harmonic orderCurrent；

l No filtering capacitors or electronic components required; reliability as high as that of dry-type transformers, with a service life of up to twenty years.

l Effectively prevents harmonic amplification.

l Avoid harmonic interference with precision equipment (such as computer crashes), leading to unnecessary losses.

l Effectively protects capacitors from overloading in reactive power compensation, extending their service life.

l Effectively reduce transformer iron and copper losses, energy-saving3-10%+

l Increase transformer utilization rates (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 the standard specification. For any special requirements, please contact us.

6Installation Method

7、Leeter Intelligent Standard Type ZeroLine Current EliminatorSelection Sheet