LLHT Electric Heat Tracing System

I. Brief Introduction to the Principle of LLHT Electric Heating System:

1. Technical Description of Intelligent Resistance Heat Tracing Cable for Long Distances

Resistant to long-distance heating cables are a special type of heating cable where the heat output per meter is consistent throughout the circuit. Different working voltages are suitable for different pipeline lengths. A single power point can supply heating for up to 80km, with a simple layout and easy maintenance. The heating cable is integrated with an intelligent temperature sensing line, which can display the temperature of each meter of the cable in real-time, monitoring its operational status.

2. LLHT cable core wires are made of alloy metal conductors

3. The insulation layer is made of imported composite insulating material. Temperature rating: 230°C.

4. Metal sheath is made of continuous alloy reinforced sheath or metal braid layer.

5. The outer sheath is made with a wear-resistant fluoroplastic layer, thickness 1.2mm.

LLHT Long Line Heating Cable Structural Diagram

Section 2: LLHT Heating Cable Technical Specifications

(1) LLHT cables are used for equipment or lines with rated working voltage of 10KV and below.

(2) The environmental temperature during cable laying shall not be lower than -20°C, with the permissible bending radius of the cable being not less than 30D (where D is the outer diameter of the cable).

(3) Long-term allowable operating temperature of cables: ≤245℃.

(4) Cable Voltage Rating: 20000V

(5) The finished LLHT cable should withstand a voltage of 35,000V at 50Hz without breakdown for 5 minutes. After being immersed in room temperature water for 1 hour, it should still withstand a voltage of 25,000V at 50Hz without breakdown for 5 minutes. The insulation resistance at 20°C should be no less than 5,000MΩ/km.

(6) Markings such as "Manufacturer of Cable, Cable Model, Voltage Rating, Length Code" are printed on the cable sheath.

LLHT electric tracing system wiring method

Y-connection (three-phase power supply)

2. U Connection (Single Phase Power Supply)

Section 3: Main Components

Transformer

LLHT Heating System, powered by a three-phase power supply. The working voltage of the system is calculated by LLHT heating engineers, and transformer manufacturers customize oil-immersed or dry-type transformers based on the voltage requirements. Utilizes aluminum alloy heat conduction bridges to increase the heat transfer surface area between LLHT and the main pipeline, protecting the LLHT heating cables. Integrated heat conduction bridges have an arched surface curvature matching the main pipeline's outer surface curvature. Separate heat conduction bridges also have an arched surface curvature identical to the main pipeline's outer surface curvature.

Control Cabinet

LLHT Heating System Control Cabinet, featuring a make/break control method, primarily utilizes vacuum contactors from ABB or Toshiba, digital temperature controllers from Fuji or Island, and has both manual and automatic control functions. The cabinet is equipped with a PLC, enabling communication with the central control cabinet to display the working voltage, current, and pipeline temperature of the LLHT system in the central control room. It achieves remote operation and monitoring. The cabinet is also equipped with a full computer terminal microcomputer protection system and an LLHT heating cable online insulation monitor. Photo:

The current LLHT heated high-pressure control cabinets are equipped with full-color touch screen control systems, displaying working voltage, current, and frequency on the touch screen. They indicate the working state of the heating circuit and working current. The system can record operating parameters for one month for future system checks. The intelligent LLHT system terminal enables monitoring the temperature of each meter of pipeline, assessing pipe insulation, and detecting leaks in the pipeline medium.

LLHT Cable

Our company owns eight large drying ovens for cable cores, two complete sets of glass fiber braiding equipment, and one set of mica wrapping equipment. We have core wire burr treatment, ultrasonic cleaning, and one set of core wire rounding equipment. We have two production lines for LLHT cable main insulation and three for composite sheath. We also have two sets of imported polarization treatment equipment, one laser marking machine, one imported full computer-controlled corona tester, one finished cable high-voltage testing device, two 10KV high-voltage insulation megohmmeters, three 5KV high-voltage insulation megohmmeters, multiple inductance and capacitance test meters, multiple oscilloscopes, and one 50KV power frequency AC withstand voltage tester. Depending on the different power supply distances of the heating system, we offer two types of LLHT cable cores: 40 square and 60 square, with the former used for shorter power supply distances. Insulating materials use imported silicone rubber that can withstand temperatures of up to 230 degrees. For cables with higher working voltages, a semi-nylon, semi-conductive layer is added between the core wire and the insulation, as well as between the insulation and the metallic sheath layer.

Metal reinforced layer production

LLHT Control Chart

LLHT Heating Control Box

LLHT heated construction