35~550KV SF6 Current Transformer
1. Product Overview
The LVQB-35~500 series of 35~550KV SF6 current transformer complies with the national standard of GB1208- 2006 "Current Transformer". It is used for current measurement, relay protection, and electric energy measurement.
2. Product Structure Our 35~550KV
SF6 current transformer has an inverted type structure. It is composed of the shell, body, insulating sleeve and the foundation.
The shell has two kinds of structure: T structure and bell type structure. The T type shell is welded by rust-proof aluminum plates and the bell type shell is made of cast aluminum materials. The shell has undergone the strength testing, air tightness testing, and X-ray flaw detection. The transformer body, including the primary winding and secondary winding, is fixed within the shell. The primary and secondary windings are insulated by SF6 gas. The shielding cylinder with secondary winding inside is supported by the epoxy insulating supports. The leading-out wires of the secondary winding are guided into the terminal box on the product base through the shielded metal bushing.
There are two kinds of insulating sleeve: porcelain bushing and silicon rubber compound bushing. The former uses high strength porcelain and the latter is mainly composed of the high strength fiber reinforced plastic tube and the silicon rubber umbrella skirt. Compared with the porcelain bushing, the silicon rubber compound bushing has better pollution flashover prevention performance, hydrophobicity transference, and electrical erosion resistance.
The connecting box, the SF6 gas density controller and the charge valve are mounted on the foundation. The SF6 gas density controller has temperature compensation function and it has two contacts to provide alarm alerts. Remote monitoring of gas pressure is achievable.
3. Working Conditions
a. High Safety
The keys to safe operation of high-voltage electrical products are whether the insulation structure is reasonable, whether the field distribution is uniform, and whether the high and low voltage electrode shape meet the requirements of the electric field distribution. After the calculation of two-dimensional and three-dimensional field distribution as well as optimal design, our 35~550KV SF6 current transformer has extremely high safety performance.
b. No Fire or Explosion Risks
Even when arc is produced inside the 35~550KV SF6 current transformer due to accidental factors, there is no risk of fire or explosion. The initial pressure increase rate becomes slow because of the compressibility of SF6 gas. No matter where the internal fault occurs, after the internal pressure slowly increases to the pressure release value, 0.8MPa, of the bursting disc, the bursting disc quickly releases pressure, so that the product housing and insulating bushing are only exposed to a low pressure. In addition, the design strength of the housing and insulating bushing is 2.5 times the failure strength.
c. Stable and Reliable Main Insulation without Aging
Our product uses SF6 gas for main insulation. SF6 has stable and reliable insulation performance, and it is free from aging. Also, it has insulation self-recovery function. d. Reliable Short Circuit Stability The primary loop of the 35~550KV SF6 current transformer is shorter than that of the oil immersed product. The SF6 type of product does not have a multilayered structure, so it has good heat dissipation. Therefore, under the premise of the same copper loss, 35~550KV SF6 current transformer has lower temperature rise, thus eliminating the risks of insulation aging after long-term operation.
e. Little Maintenance, Reliable Operation
The annual leakage rate of SF6 gas is controlled within 0.5%, while the national standard specifies this parameter value to be within 1%. In the case of gas leakage rate of 1%, the insulation of 35~550KV SF6 current transformer is stable within 10 years, requiring no maintenance. In addition, the gas density can be monitored through the density controller installed in the product. When the gas pressure inside the product decreases to a certain value, the density controller issues an alarm signal, thus ensuring safe and reliable operation of the product. If the gas pressure inside the product decreases to the external atmospheric pressure, i.e., zero gauge pressure, our product can still run at the rated phase voltage, so users have sufficient time to take corresponding measures.
5. Technical Parameters
a. The above picture shows a conventional 35~550KV SF6 current transformer. If there is a change in parameter when ordering, product dimensions will vary. Then, the demand and supply sides can re-negotiate.
b. Dimensions of the bell type product are provided separately.
Current Sensor | Gas Insulated Transformer | High Current Inductor.