Mercury Slip Rings (Liquid Metal Contact)
Liquid metal instead of brushes: no sliding wear, no carbon dust, and a contact resistance that stays flat for the life of the unit. Our A / W series covers 25 A to 450 A single-channel, up to 400 V.
Key specifications
Specifications
| Parameter | Value | Notes |
|---|---|---|
| Contact system | Liquid metal (mercury) | No brush, no sliding wear, no carbon dust |
| Current range | 25 A to 450 A single channel | Model depends on current; see table below |
| Voltage | 400 V | Confirm dielectric clearance for your application |
| Rotation speed | 400 – 1800 rpm | Higher speed models are lower current |
| Channels | Single channel per unit | Multiple units can be stacked on one shaft |
| Contact resistance | Very low and stable | The main reason to choose liquid metal |
| Wear parts | None | No brush replacement interval |
| Mounting | Shaft or flange, orientation matters | Confirm mounting angle before ordering |
| Operating temperature | Confirm for your model | Liquid metal behaviour is temperature dependent |
Where mercury slip rings make sense
- High-current rotating joints — heating rollers, rotary welding equipment, electroplating lines
- Low-level signal paths — where contact noise must be minimised and brush noise is unacceptable
- Clean-room and dust-sensitive equipment — no carbon brush debris
- Maintenance-free installations — no brush inspection interval
- Large test stands — steady contact resistance through long runs
Model range (A / W series)
| Model | Current | Voltage | Speed | Channels |
|---|---|---|---|---|
| W1M500ST | 450 A | 400 V | 400 rpm | 1 |
| W1M300ST | 300 A | 400 V | 1000 rpm | 1 |
| W1M180S-D | 180 A | 400 V | 1000 rpm | 1 |
| W1M120S-D | 120 A | 400 V | 1200 rpm | 1 |
Lower-current models in the same series are available on request. Current, speed and channel count trade off against each other — tell us your combination.
Mercury vs brush vs precious-metal contacts
| Aspect | Mercury (liquid metal) | Brush | Precious-metal wire |
|---|---|---|---|
| Contact resistance | Very low, stable | Higher, varies with wear | Low, stable |
| Wear debris | None | Carbon dust | Minimal |
| Current capacity | Up to 450 A single | High | Up to 20 A per ring |
| Maintenance | None | Brush inspection and replacement | None in rated life |
| Mounting constraint | Orientation matters | Flexible | Flexible |
Frequently asked questions
Can I mount a mercury slip ring at any angle?
No — each model has a preferred orientation so the liquid metal stays in contact with the rotating parts. Tell us the mounting angle during selection, not after delivery.
How many channels can I get?
The A / W series is single-channel per unit. For multiple channels, several units can be stacked on the same shaft, or a precious-metal multi-ring unit may be the better choice.
Is there a maintenance interval?
There is no brush to replace. The bearing and seal still have a service life, so the practical limit is mechanical rather than electrical.
What about 450 A at high speed?
Current and speed trade off: the 450 A model runs to 400 rpm, while the 120 A model reaches 1200 rpm. Tell us both and we will confirm the model that meets your combination.
Need a high-current mercury slip ring?
Send the current, voltage, speed and mounting orientation — you will get a model recommendation and quote, usually within 5 hours.
