Control cable metal shield type selection, should according to the possible electrical interference, included in the comprehensive measures to suppress interference, and should meet the requirements to reduce interference or over voltage, at the same time, we should comply with the following provisions:
(1) the weak control cable is located above 110kV power distribution equipment, should choose the general shield or a double-layer shield.
(2) for integrated circuit, microcomputer protection current and voltage and signal contacts should be used in shielding control cable.
(3) shielding signal computer monitoring system of loop control of cable selection, shall meet the following requirements:
1) switch signal, can use the total shielding.
2) high level analog signal, it is appropriate to use the total shielding of the core, when necessary, can also be used to shield the core.
3) low level analog signal or impulse signal, it is appropriate to use the core of the twisted pair shielding, when necessary, can also be used for the total shielding.
(4) other, according to the electromagnetic induction, electrostatic induction and ground potential rise higher impact factors, selection of suitable shielding type.
(5) cable with steel armor and metal sleeve, should make full use of the shielding function.