1)产品结构与工作原理 
 Product Structure and Working Principle 

 三根平行的绝缘铜线为电源母线，在内护套绝缘层外缠绕电热丝，并将该电热丝每隔一定距离分别依次与三根电源母线循环连接，在每二相间形成连续并联电阻。当母线通以三相电后，各并联电阻同时发热，因而形成一条连续的加热带。
Three parallel insulation copper wires form power generatrix. Electric heating threads are wound around the inner jacket insulation layer ln every certain distance, the heating thread is welded in turn to the three power generatrix circularly. This makes every 2 phases into acontinuous parallel connection resistance. When the generatrix is connected to 3 -phase power supply, the every parallel resistance heats at the same time This makes a continuous heating belt.
Product Types and Main Technical Characteristics 

JFB-30/3J型恒功率并联电热带主要技术参数表 
Table 2-2: Main Technical Parameters of JFB- 口 /3 Type Electric heat cable

(3)产品特点及应用场合
Product Characteristics and Applications 

优点：
Besides the above characteristics the three phase heating cables have following advantages: 
①率的三相电热带的Z大允许使用长度是单相电热带的三倍。
The most tolerable length of the three-phase heat cable is three times longer than the length of the single-phase heating cable of the same wattage.
②三相带截面大，传热导面积大，能提高传输效率。
Bigger section area of three phase heating cable can broaden heat transmitting area and thisincreases the transmitting efficiency.
 
三相并联带一般适用于大管径，管网系统管线和罐体的伴热保温。
Three phase parallel connection heating cables are suitable forthethermal insulation of pipes with big diameters, pipe lines in nets and tanks.