Spectrum Control Blog

Electromagnetic Interference in Slip Ring Assemblies

Written by Amy Brown | Oct 5, 2021 2:52:48 PM

Slip rings are an essential electrical component found in military, industrial and medical equipment. With a 360 degree continuous rotating structure, high-performance slip ring assemblies allow power and electrical signals from a stationary to a rotating structure by making an electrical connection without turn limits. These power and signal lines pick up electrical noise that needs to be filtered so the systems function as they should.

Electromagnetic interference (EMI) shielding or electromagnetic compatibility (EMC) is critical.

Military Slip Ring Applications & EMI Filtering Solutions

The Armed Forces have many operations that require slip ring designs. Pedestal products for mobile surface-to-air missile systems, ground vehicles with movable turrets, and radar platforms benefit from filtered circular connectors to control EMI and keep it from destroying the slip ring systems.

EMI filtered circular connectors from APITech are available in stainless steel, aluminum, composite shells, ideal for environmental and weight-sensitive applications. Cadmium, nickel, black nickel-zinc plating connectors are excellent for defense, RoHS, and harsh environments. Connectors for transient survival that meet criteria for RTCA/DO-160, level 4 (1,500 voltage transient) are also available.

EMI Filtered D-Sub Connectors

Military electro-optical and infrared systems with 360 degrees of motion call for slip ring technology in the design. These systems require filtered D-sub connectors. The rotating systems will transmit power or signals, allowing energy flow between two electrical rotating parts, such as a motor, susceptible to EMI.

D-sub filtered connectors are designed for high reliability and demanding environmental applications. These connectors have various termination options such as PC mount, wire wrap, solder cup, and 90° PCB. APITech manufactures a wide range of capacitance and selectively loaded designs, including a large capacitance pin-to-pin ratio range, providing power and signal filtering in a single package.

Medical and Commercial Applications for Slip Rings

Medical equipment, including MRI machines, feature this technology. These systems require complete suppression of all EMI and low-leakage, non-magnetic properties to prevent negatively affecting surrounding equipment.

Industrial equipment such as heliostats, wind turbines, and down hold oil wells require components with rugged construction with design flexibility to meet demanding environmental and performance requirements.

Commercial equipment like radio telescopes, Ferris wheels, and motion simulators benefit from a rotating object to transfer power, control circuits, or analog or digital signals. Discrete EMI filters will keep the wheels turning on all of these systems.

Discrete EMI filters like resin sealed filters are cost-effective and have design flexibility with various sizes, lead options, and circuit configurations. Hermetically sealed filters feature hermetic glass seals with high EMI filtering performance. They are impervious to high moisture environments, solvents, and severe conditions.

Slip rings are also known in the industry as rotary electrical interfaces, rotating electrical connectors, collectors, swivels, or electrical rotary joints.

In-House EMC Test Lab

Crucial to finding a solution to an EMC problem is the ability to test for compliance. APITech’s engineers are EMC experts with decades of design experience and with a fully equipped EMC testing laboratory at the ready to support customer compliance with specific system requirements.

We conduct a wide range of EMC and environmental tests to help us identify potential issues and recommend design solutions. Our extensive in-house test capabilities allow for a faster turnaround of your complete design solution and lower total cost.

  • Ambient-free in-house shielded anechoic chamber
  • NARTE certified engineering staff
  • Highly accurate computer-controlled instrumentation accumulates and presents data in multiple formats
  • Testing to military and international commercial regulations

APITech's diagnostic testing capabilities and excellent manufacturing provide power filter solutions to satisfy global EMC standards while meeting unique design parameters.