How to Specify a 160 mm Through-Bore Slip Ring for Industrial Automation

Industrial automation equipment often needs to transfer power and data across a rotating interface. The mechanical design may also require a large central opening for a drive shaft, pipe, cable bundle or other machine component.

A 160 mm through-bore slip ring can meet these requirements within one rotary assembly. The correct configuration depends on the electrical loads, Ethernet architecture, installation space and operating environment.

The LPT160-0525-0816-01PE-3405-03E3 provides a useful project reference. It combines a 160 mm through-bore with several current levels, protective earth and three Gigabit Ethernet channels.

Start with the function of the central opening

The through-bore should be defined before the external dimensions of the slip ring are finalized.

A machine builder should identify what passes through the 160 mm opening. This may include:

• A mechanical shaft

• Pneumatic or hydraulic piping

• Existing cables

• A mounting tube

• A separate optical or fluid rotary joint

The specification should include the maximum diameter of the passing component, its tolerance, possible eccentric movement and the required assembly clearance.

Using only the nominal shaft diameter may leave insufficient space for manufacturing tolerances or installation.

Prepare a circuit-by-circuit power schedule

This reference configuration contains:

• Five 25 A circuits

• Eight 16 A circuits

• Thirty-four 5 A circuits

• One protective-earth circuit

These circuits should not be represented as one total current value. Each load group may have a different function, duty cycle and peak-current profile.

The machine builder should provide the rated current, working voltage and expected duty cycle for every circuit. Loads that start frequently or create short current peaks should be identified separately.

The protective-earth circuit should also be defined in the electrical documentation. Its arrangement must follow the safety design of the completed machine.

Define the three Ethernet channels

The product includes three Gigabit Ethernet channels. The system specification should still define:

• Cable category

• Shielding construction

• Connector type

• Cable length on both sides

• Grounding method

• Network topology

• Required data rate

• Acceptable error criteria

Ethernet performance depends on the complete link. The slip ring, cables, connectors, switches and connected devices should therefore be evaluated as one system.

Plan power and data together

Power circuits and Ethernet channels share the same mechanical housing, but they have different transmission requirements.

High-current circuits affect conductor size and thermal design. Ethernet channels require controlled cable construction, shielding and routing. The internal layout should therefore be planned around the complete channel list.

If the circuit schedule changes late in the project, the dimensions and internal arrangement may also need to change.

Check the installation envelope

The 160 mm opening does not define the complete product size. Engineers should also confirm:

• Maximum permitted outside diameter

• Available axial length

• Mounting surface

• Fixed and rotating sides

• Cable exit directions

• Cable bend radius

• Access for installation tools

• Space required for maintenance

The slip ring should not be used as the main supporting bearing unless the approved design explicitly allows it.

Adapt the specification to Asian automation projects

Equipment built for factories across Asia may be installed in different climates and plant environments. The RFQ should state the actual temperature, humidity, dust exposure and cleaning method instead of using a general regional assumption.

For equipment built in one country and installed in another, drawings, terminal labels and cable identification should be agreed before shipment.

Information to include in the RFQ

A useful RFQ should contain:

• Complete circuit schedule

• Current and voltage for every circuit

• Three Gigabit Ethernet channel requirements

• Required through-bore clearance

• Rotation speed and duty cycle

• Maximum outside dimensions

• Installation orientation

• Cable and connector requirements

• Environmental conditions

• Required inspection and maintenance access

A complete specification allows the supplier to evaluate the electrical and mechanical requirements together. It also reduces changes after the machine layout has been released.