FF-A-1*2*18AWG Fieldbus Communication Cable

FF-A-1*2*18AWG Fieldbus Communication Cable

FF-A-1*2*18AWG Fieldbus Communication Cable is suitable for process automation control and connection lines between measurement instruments in factory foundation control field environments. It is used to construct an open, decentralized digital fieldbus communication system. Ideal for installation on cable racks (bridges) or inside pipelines, both indoors and outdoors, in moist or dry conditions.

FF-A-1*2*18AWG Fieldbus Communication Cable Tin-plated Copper Core Flexible Conductors 18AWG, Polyethylene Insulation, Red/Green Color, Double Shielded, Type A, FF Fieldbus Cable. The conductors of FF-A type cables can also be made of soft copper wire according to customer requirements.

FF-A-1*2*18AWG Fieldbus Communication Cable Performance Parameters Table

FF-A-1*2*18AWG Fieldbus Communication Cable usage experience shows that one of the main causes of fieldbus loop failures is interference from the network segment, and the main reason for interference is poor installation of the fieldbus network segment and bus equipment. Installation experience includes:

Fieldbus network segments have high insulation requirements. To prevent explosions and moisture from entering the bus loop, explosion-proof junction boxes of increased safety type (EExe) are specified. When using explosion-proof cables, explosion-proof cable seals should be used for the cables entering the junction box.

Utilizing FF bus-specific terminal blocks for connection with each field bus device. Each bus-specific terminal block features short-circuit protection, with an indicator light illuminating upon a short circuit to ensure that a single branch short circuit does not affect the normal operation of other branches. The short-circuit protector limits the short-circuit current per branch to no more than 60mA.

②Cable Shielding Layer Connection Precautions. On fieldbus equipment, the shield wire of the branch cable must be cut and insulated with tape, and should not be connected to the grounding screw of the housing. The shield wires of each segment of the bus cable should be connected together through grounding terminals within the junction box. The shield wire can only be grounded at the cabinet side (marshalling) terminals. The insulation from ground must be good at any intermediate point, and there should be no multiple grounding situations. This can prevent static induction and low-frequency (50Hz) interference.

If the main cable is a multi-core cable, the shielded wires of different bus segments should not be interconnected within the junction box (JB) nor connected to the overall shielded wire.

After the installation of fieldbus cables and field equipment, rigorous testing should be conducted. The insulation resistance between cables, ground insulation, capacitance between cables and ground, as well as the waveform of the bus signal, should meet the technical requirements of the FF Foundation's fieldbus system engineering guidelines. The connections of all terminals must be securely tightened.

Section 2: Installation and Testing Methods for FF Fieldbus

Fieldbus physical signals, terminations, power supplies, and inherent installations differ from conventional instruments; the cables used for both must be distinguished. Cables for the fieldbus, available at communication speeds of 31.25kbps, must be selected based on engineering requirements. Type A is generally used for new installations; Type B can be used as a substitute; Types C and D are only used for modified installations.

In engineering, attention must be paid to the shielding and grounding of cable lines, including A and B type shielded cables. C and D type cables can also be shielded by passing the conductors through a metal tube and then connecting them together for grounding. The polarity issue between the cable line and the equipment must be noted; hence, the Manchester signals used in field buses are alternating voltages, with each bit changing polarity once or twice. This alternating voltage only exists in non-powered networks. In powered networks, alternating voltage is superimposed on the direct current voltage supplying the equipment. In either case, the field bus receiving circuit only focuses on the alternating voltage. The transitions of positive and negative voltages represent different meanings, so the field bus signals are polarized. The power supply equipment for the bus is also polarized and must be connected with the same polarity. Cabled lines with color markings are used for convenience during construction. Currently, there are also non-polarized devices for network power supply that can automatically detect and correct polarity, correctly receive signals of different polarities, and can be connected blindly during use.