Configured for high-speed signal termination and line impedance matching in Bailey Infi 90 networks, the ABB NKTT01-8 (NKTT01 Infi-Net Termination Cable) provides direct physical/electrical execution. This 8 ft assembly maintains transmission line integrity across distributed control nodes, preventing signal reflection and attenuation along high-frequency communication lines. It establishes isolated 75 ohm termination points between processing modules and field bus segments without introducing network noise or line distortion.

Part Number Breakdown & Configuration Matrix

• NKTT01: Base assembly designation for Bailey Infi 90 Infi-Net coaxial termination cable.
• -8: Specified cable segment length in feet (8 ft / 2.44 m total assembly length).
• Integrated Termination: Factory-fitted 75 ohm non-inductive load resistor (1% tolerance) built directly into the cable end for optimal bus matching.

Physical & Electrical Parameters

Backplane Communication & Deterministic Network Integrity

The NKTT01-8 ensures continuous backplane bus communication velocity and deterministic signal transmission across Infi-Net loops. By maintaining strict impedance matching (75 ohm +/-3 ohm) and low signal attenuation (<= 0.20 dB/m at 5 MHz), the assembly prevents packet corruption in high-throughput 5 Mbit/s HDLC protocols. The 1 kV RMS galvanic isolation between the inner braid shield and outer jacket suppresses common-mode noise and ground loop currents. This protects node electronics and maintains firmware flash compatibility across network nodes during continuous DCS operation.

Package Contents & Ordering Details

• 1 x ABB NKTT01-8 Infi-Net Termination Cable Assembly (8 ft / 2.44 m)
• Integrated 75 ohm bus terminator resistor module
• Standard factory-sealed protective polybag packaging

Site Installation & Cable Handling Rules

• Bend Radius Compliance: Maintain a minimum static bend radius of 50 mm during installation to prevent deformation of the dielectric core and shield integrity.
• Grounding Requirements: Ensure the outer shield isolation is preserved along the cable tray; do not strip the outer jacket or short the outer shield to local enclosure earth except at designated system grounding points.
• Connector Strain Relief: Support the cable assembly within 100 mm of the module connection port to relieve strain on the termination junction and interface pins.
• Routing Distance: Keep the termination cable isolated by at least 300 mm from high-voltage AC power lines and variable frequency drive cables to mitigate electromagnetic interference.

Technical Support FAQ

• What is the primary function of the built-in 75 ohm resistance?

  It terminates the Infi-Net coax line to match characteristic impedance, eliminating signal reflections that cause HDLC frame corruption.

• Can the cable length be shortened or lengthened manually in the field?

  No, altering the physical length disrupts calibration, velocity factor, and impedance parameters, leading to signal degradation.

• Is the NKTT01-8 cable hot-swappable during active network operation?

  Disconnecting the cable interrupts bus termination, which can destabilize communication across active nodes on that network loop.

• How do you test if the internal terminator resistor is functional?

  Measure resistance across the core conductor and inner shield with a digital multimeter; it must read 75 ohm (+/-1 ohm).

• What is the purpose of the 1 kV RMS shield isolation rating?

  It prevents ground potential differences between remote cabinets from driving circulating currents through the coaxial shield.

• Does this passive cable draw power from the Infi-Net interface card?

  No, it operates as a completely passive termination device and draws zero current from the host controller or node backplane.

• How does velocity ratio affect signal propagation in this assembly?

  A velocity ratio of 0.82 ensures rapid signal travel time, minimizing latency and phase shifts over the 2.44 m transmission span.

• What environmental protections are recommended for harsh field installation?

  Route inside closed conduits or sealed wireways to stay within the -20 ... +80 deg C operating range and avoid physical abrasion.