Mersen Slip Ring Assemblies
The performance of your motors depends on the efficient interaction of components such as slip ring assemblies
The performance of your motors depends on the efficient interaction of components such as slip ring assemblies
Technical documentation
- Slip rings & brush rockers for hydro power
pdf - 399.89 KB
- GE-Hitachi 1.X Platform SR 13-15 Slip Rings
pdf - 372.08 KB
-
Mersen Slip Ring Assemblies: Compatibility Guide and Application Reference
Mersen designs and manufactures slip ring assemblies for four distinct application families: wind generators, hydro turbines, industrial wound-rotor motors, and signal-and-power transfer applications. Across all four, the same engineering logic applies — the slip ring is the rotating electrical interface between static and rotating parts of the machine, and its material, geometry, and surface finish determine the wear rate of every carbon brush in contact with it. Getting the ring right is as important as getting the brush grade right.
This page maps the Mersen slip ring range by application, platform, and compatibility, and gives the technical selection criteria that determine which assembly is appropriate for a given machine. For operators or procurement teams who know they need a Mersen slip ring and want to identify the correct reference, the compatibility table below is the starting point.
-
Mersen slip ring range
Compatibility by application
Scroll
Market / application Platform / type Ring material Product page Wind (DFIG) GE-Hitachi 1.X (1.5-1.85MW) Bronze SR 13-15 Wind generator slip rings Wind (DFIG) GE 2.X, Vestas, Siemens, Suzlon, Gamesa Bronze or stainless Wind generator slip rings Hydro Large-format OEM generators Forged steel, bronze Hydro power generator slip rings Industrial Wound-rotor induction motors Non-ferrous, stainless, copper Industrial wound motor slip rings Signal & power Water treatment, material handling Bronze, PMMA Power and signal slip rings -
Wind
Wind turbine generator slip rings: the SR 13-15 bronze retrofit
The most widely deployed Mersen slip ring in the US onshore wind fleet is the SR 13-15 bronze assembly for GE-Hitachi 1.X generators. It is a direct retrofit for the 1.5MW, 1.6MW, 1.7MW, and 1.85MW platforms, replacing the original stainless steel ring without any modification to the existing slip ring cabinet.
The performance case for the SR 13-15 is grounded in field data from over 4,000 units operating across the United States. Measured against the stainless steel original:
- operating temperature on slip ring, holders, and brushes drops by 30 to 40% in field conditions
- brush wear rate falls by 30 to 40%, with service intervals extending beyond four years on optimised grade pairings
- NDE bearing temperature faults are reduced, as the lower ring operating temperature propagates through the adjacent bearing
- WETA card protection is improved through more robust grounding contact geometry.
-
The material difference between bronze and stainless steel is the root cause of these gains. Stainless steel has higher electrical resistivity and lower thermal conductivity than the bronze alloy used in the SR 13-15 — two properties that directly drive heat generation at the brush-ring contact interface. At loads above 1.5 MW, this difference is measurable in operating temperature, and the temperature delta compounds over time through accelerated brush wear and bearing degradation.
For other wind turbine platforms — Vestas, Siemens Gamesa, Suzlon S-64/S-88, Gamesa 8.X/9.X — Mersen engineers application-specific slip ring assemblies based on the generator manufacturer's shaft and cabinet geometry. The full range is accessible on the wind generator slip rings page, where specifications and retrofit documentation are available.
-
hydro
Hydro generator slip rings: large-diameter custom engineering
Hydro power generators present a different set of constraints from wind. Rotor diameters are substantially larger, excitation currents are higher, and the machines typically operate continuously at low peripheral speed under OEM-specified maintenance intervals measured in years rather than months. Mersen's hydro power generator slip rings are designed in cooperation with major OEMs and are fitted to some of the largest hydroelectric generators in operation.
Key design parameters for hydro slip ring assemblies:
- ring diameters from 170mm up to 2,500mm for the largest machines
- ring materials: forged steel, low-carbon steel, stainless steel, or bronze depending on the OEM specification and grade pairing
- insulating materials: mica and fiberglass, both OEM-approved
- quality controls: Megger and hi-pot dielectric testing up to 60kV during assembly and after machining, plus ultrasonic testing to verify material integrity
- designed for both synchronous and asynchronous generator architectures
-
Refurbishment of existing hydro slip ring assemblies is also available. For asset owners managing aging hydro equipment, refurbishment is an economical alternative to full ring set replacement that can restore electrical and mechanical performance to as-new specification.
-
Industry
Industrial wound-rotor motor slip rings
Wound-rotor induction motors (also called slip ring rotor motors) use a slip ring assembly to transfer current to the rotor windings during starting and speed control.
Mersen's industrial wound motor slip rings cover motors from a few kilowatts up to 6MW, with both moulded and machined ring construction depending on the operating speed.
Material options for industrial slip rings include non-ferrous alloys, stainless steel, and copper alloys. Helically-grooved rings are available for applications where self-cleaning and reduced brush bounce at speed are required. The full range covers operating voltages from 220V to 3,000V AC, insulation classes H and F, and peripheral speeds up to 3,600 rpm for machined ring variants.
-
Refurbishment of in-service ring sets is available. Worn or corroded rings can be resurfaced, re-insulated, and returned to service at a fraction of the cost of a new assembly, provided the ring body has sufficient remaining wall thickness.
-
Process
Signal and power slip rings
For applications requiring concurrent power and signal transmission through the same rotating interface — water treatment aeration drives, material handling equipment, crane systems — Mersen's power and signal slip rings provide modular assemblies covering up to 16 tracks, rated to 25A and 400V AC, with IP54 protection and operating temperatures from -25 to +60 degrees Celsius.
These assemblies are available in the C3046 and C3042 series, with bronze rings and corrosion-resistant polymer brush holders. They are vertically mountable and include stainless steel shaft fastening for direct hub attachment. Cable glands are supplied as standard.
-
How Mersen slip ring material choice affects carbon brush life
The slip ring material is not an isolated choice: it directly determines which carbon brush grades for generators are appropriate, and the combination of ring material and brush grade together determine the service interval. The interaction is tribological: the friction coefficient, film formation characteristics, and heat dissipation behaviour of the brush-ring pair are co-determined by both surfaces.
The practical implications for selection are:
- bronze rings have lower resistivity and higher thermal conductivity than stainless steel, which means lower operating temperatures and gentler brush wear at equivalent current densities — the primary reason the SR 13-15 bronze ring outperforms the stainless original on GE-Hitachi platforms
- stainless steel rings are harder and more wear-resistant mechanically, which suits applications with abrasive environments or where ring replacement is more difficult than brush replacement
- copper alloy rings offer the highest conductivity and are preferred for high current density applications where resistive losses must be minimised
- the brush grade must be matched to the ring material: running a grade optimised for bronze on a stainless ring produces a different wear curve and contact film from the specification, potentially shorter brush life and higher temperatures
Mersen's brush-holders for generators are co-engineered with the slip ring assemblies to deliver the correct spring force curve and contact geometry across the full brush wear range. Using third-party holders with Mersen rings — or vice versa — introduces a variable that can shift the operating point away from the design specification.
-
Retrofit, refurbishment, and in-stock availability
The SR 13-15 bronze slip ring for GE-Hitachi 1.X platforms is held in stock in the US for immediate availability. Other wind platform references are available on lead times that depend on configuration. Hydro and industrial assemblies are engineered to order based on machine data.
For wind fleet operators, Mersen's Windtracker® wind services team coordinates component supply with scheduled maintenance visits, reducing the logistics overhead of managing slip ring replacements across a large turbine fleet. The same team handles in-field refurbishment assessment: for rings that are worn but not beyond serviceable limits, resurfacing at nacelle height is sometimes possible, deferring a full ring change to the next planned access.
-
Focus on
Slip rings for the wind market
-
Frequently Asked Questions
-
What is a Mersen slip ring and how is it different from a standard slip ring?
A Mersen slip ring assembly is a precision-manufactured rotating electrical interface engineered for specific application environments: wind generators, hydro turbines, industrial motors, or signal transmission. The difference from a generic slip ring lies primarily in material engineering and co-design with the brush system. Mersen develops its own carbon brush grades in-house and validates ring-and-brush combinations on test benches before field deployment. The result is a ring surface whose hardness, conductivity, and finish are optimised for the specific grade that will run against it, rather than a general-purpose surface that must accommodate any brush.
-
Can a Mersen slip ring be installed on a non-Mersen generator?
Yes. Mersen slip ring assemblies are supplied as retrofit units for a wide range of OEM generators. The SR 13-15 for GE-Hitachi 1.X is the primary example: it is a plug-and-play retrofit that requires no modification to the existing cabinet or rotor. For other generators, Mersen engineers the ring set to the shaft diameter, cabinet geometry, and electrical specification of the target machine. The Mersen PTT North America team in Boonton, NJ handles compatibility enquiries and can advise based on the generator data sheet or an existing ring set drawing.
-
What is the lead time for a Mersen wind turbine generator slip ring?
The SR 13-15 for GE-Hitachi 1.X platforms is typically available from US stock. Other wind platform references and custom-engineered assemblies have lead times that vary based on configuration and current production scheduling. For planned maintenance programmes, Mersen recommends confirming availability at least six to eight weeks ahead of the target installation date to avoid scheduling conflicts. Hydro and industrial assemblies are build-to-order and carry longer lead times depending on the diameter and complexity.
-
Is refurbishment of an existing Mersen slip ring possible?
Yes, in most cases. Slip ring refurbishment involves resurfacing the ring tracks to remove oxidation and wear grooves, re-insulating if required, and restoring the ring to a defined surface roughness and runout specification. Whether refurbishment is viable depends on the remaining wall thickness of the ring body — Mersen's engineering team can assess this from dimensional data or a physical inspection. For hydro generators and large industrial machines, refurbishment is frequently the more economical route compared to full ring set replacement.
-
How do I identify the correct Mersen slip ring reference for my turbine?
The most direct route is the turbine model and generator manufacturer's designation. For GE 1.5MW non-ESS and ESS variants, GE 2.X, Suzlon S-64/S-88, and Gamesa 8.X/9.X, Mersen has documented references. For other platforms, the generator manufacturer's part number or an existing ring set drawing allows Mersen's engineering team to confirm the correct assembly. Contact Mersen PTT North America at contact.ptt.na@mersen.com with the turbine OEM, generator model, and rated power.
-
