NEWS CENTER
Choose National Standard, Choose Safety; Buy With Comfort, Use With Confidence！
Installation measures for control cables
Release Time：
2024-04-03
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
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 range in the event of insulation breakdown, mechanical damage, or fire, the national standard GB50217-91 "Code for Design of Power Engineering Cables" stipulates that for two sets of systems that require enhanced reliability, such as 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 an issue of electrical interference between different cores of the same cable and between adjacent parallel cables. The main reasons for electrical interference are:
(1) The electrostatic interference generated by the coupling of capacitance between cores due to external applied voltage;
(2) Electromagnetic induction interference caused by energized current. 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 the control circuit of a high-voltage substation's split phase operation circuit breaker, a single cable was used for three phases. This accident occurred in the past, where the pulse of the split phase operation triggered the thyristors of other phases, mistakenly leading to three-phase linkage. In the future, separate and independent cables were used, and no more false tripping accidents occurred. For example, in the computer monitoring system of a certain power plant, due to the use of a four core cable that combines the low-level analog signal line with the power line of the transmitter, a 70V interference voltage was generated on the signal line. This obviously affects the normal operation of the low-level signal circuit measured in millivolts.
Keywords：
Latest News