The rated voltage of the control cable should not be lower than the working voltage of the circuit, and should meet the requirements of transient and power frequency overvoltage that may be experienced. [3] To ensure that the control cable reduces the affected area in the event of insulation breakdown, mechanical damage, or fire, the national standard GB50217-91 "Code for Design of Cables in Power Engineering" stipulates that for two systems that require enhanced reliability, including dual protection current, voltage, DC power supply, and trip control circuit, independent control cables should be used.

After the control cable is put into operation, there is a problem of electrical interference between different cores of the same cable and between adjacent parallel cables. The main causes of electrical interference are:

(1) Due to the electrostatic interference generated by the coupling of capacitors between cores caused by external voltage;

(2) Due to electromagnetic induction interference caused by the current passing through. Overall, when there are high voltage and high current interference sources nearby, electrical interference is more severe. Due to the smaller distance between the cores of the same cable, the degree of interference is much greater than that of adjacent cables laid in parallel. For example, in a high-voltage substation, the control circuit of a phase separated operation circuit breaker used a single cable for all three phases. Such an accident once occurred, where the pulse from the phase separated operation triggered the thyristors of other phases, resulting in three-phase linkage. Later, separate independent cables were used, and no further misoperation accidents occurred. For example, in the computer monitoring system of a certain power plant, the use of a four core cable to share the low-level analog signal line with the power line of the transmitter caused interference voltage of 70V on the signal line, which obviously affected the normal operation of the low-level signal circuit measured in millivolts.

Fujitomo Optronics Technology Co., Ltd. (in the short name: FUJITOMO), established in 2019, is located on the 6th floor (sales office) of  Tianhui Building, Longhua District, Shenzhen. The FTTX accessories production base is located in the National High-tech Industrial Park of Leizhou City, Guangdong. by, for now, we have currently employed about 290 people, covers an area of 43,000 square meters, up till now the total investment in fujitomo is about USD 6million, specializing in the production of various indoor and outdoor optical fiber cables and optical fiber connectors,Fiber Cleavers, fusion Splicer, OTDR ,Fast connectors, ODP CAJA box,OLT,ONU ,the products are widely used by telecom operators in the world. 97% of the products are exported to more than 60 countries around the world.

Fujitomo has the ability to produce a full range of optical cables, ABF cables, ADSS,Fig8 various types of direct buried, pipeline and aerial optical cables, as well as indoor and outdoor butterfly optical cables, building distribution cables, and access cables. The annual output capacity of optical cables is 4.7 million core kilometers. The FTTX accessories production base is mainly centered on FTTH FTTA supporting facilities, and independently produces PLC splitters, fiber optic fast connectors, fiber jumpers, FTTA base station waterproof jumpers, MPO/MTP 5G data center supporting products, etc., with an annual production capacity of 42 million PCS connector. At the same time, we work with many customers to develop and design Optical fiber cable, patch cord, MTP/MPO, Fiber Cleaver , Fusion Splicer , OTDR , OLT,ONU ,optical fiber distribution boxes, optical cable connection boxes, indoor and outdoor cabinet, etc. to meet the needs of different customers for the market, and provide customers with one-stop procurching services.