Salt air, 95% humidity, constant motion, and temperature swings: a ship or an offshore platform is one of the worst places on earth to be an electronic component. High voltage reed relays hold up in that environment because the switching contacts live inside a hermetic glass envelope, and the environment never touches them. That single property explains most of what follows.
What the marine environment throws at electronics
- Salt fog and corrosion: NaCl exposure degrades unprotected metals
- High humidity: up to 95% RH in engine rooms
- Constant motion: pitch, roll, and yaw stress every assembly
- Wide temperature range: −25 °C to +70 °C ambient
- Salt water immersion: IP67+ needed for deck equipment
A reed relay’s hermetic sealing keeps the contacts clean in salt air. With no external moving parts, motion-induced wear is not a failure mode. Isolation voltages cover shipboard high voltage systems, service life runs past 10 years, and coil power is low enough for battery-backed systems.
Where they are used on board
Power distribution
Generator synchronizing, bus transfer between power sources, priority-based load shedding, and fault isolation in marine switchgear. HVR series (4–15 kV), with custom high-current configurations where the bus demands it.
Navigation and communication
Radar switching in dual magnetron backup systems, AIS antenna switching, VSAT and INMARSAT power control, and GPS/GLONASS position sensor multiplexing. HM05 series and MRS01-06 are the usual choices.
Deck equipment
Anchor windlass motor control and status feedback, crane and winch limit switching, mooring tension monitoring, and hatch cover position sensing. MRS07-13 IP67 reed sensors with HM05 control relays.
Engine room
Engine start/stop logic, lubrication pressure switch feedback, cooling temperature sensor isolation, and turbocharger exhaust monitoring. HM05 for control logic, HVR where the voltages are higher.
Safety systems
Fire detection sensor isolation, bilge level alarms with fail-safe outputs, fuel leak detection, and emergency shutdown logic with latching relays. These circuits are where series-parallel redundancy configurations earn their keep.
Offshore platforms and subsea
Platform ballast control, oil and gas separation process control, wellhead actuator switching, and custody transfer metering call for HVR and HRX series parts. Subsea work, including ROV tool control, subsea Christmas tree hydraulic switching, pipeline inspection sensor multiplexing, and cathodic protection anode monitoring, uses purpose-built subsea relays; consult the factory for these.
Standards and testing
| Standard | Scope |
|---|---|
| DNV-GL | Classification society requirements |
| ABS | American Bureau of Shipping |
| Lloyd’s Register | Marine certification |
| IEC 60945 | Maritime navigation equipment |
| IEC 60533 | EMC on ships |
Deck equipment needs IP56 minimum, IP67 preferred for watertight compartments. Environmental testing follows IEC 60068-2-52 for salt fog, IACS E10 for vibration, temperature cycling across the −25 °C to +70 °C range, and humidity at 95% RH at 40 °C.
Selection quick reference
| Application Area | Voltage | Current | Protection | Recommended Series |
|---|---|---|---|---|
| Navigation systems | 24 V | <1 A | IP56 | HM05 |
| Engine room | 110–440 V | 1–5 A | IP44 | HVR |
| Deck equipment | 24–110 V | <2 A | IP67 | MRS07-13 |
| Power distribution | 690 V–4.5 kV | <10 A | IP20 | Custom HVR |
| Safety systems | 24–110 V | 1–2 A | Redundant | HM05 redundancy |
| Subsea | Up to 5 kV | <1 A | External housing | Custom |
ESD systems: how the architecture goes together
A platform emergency shutdown design illustrates the pattern that works. IEC 61511 SIL 2 compliance is the target, salt spray exposure is constant, and the service life requirement is 20+ years. The approach that meets it: custom HVR-15 kV reed relays in a triple-modular redundancy architecture, IP67 enclosures with conformal coating. The hermetic contacts are what make the redundancy trustworthy; each channel degrades so slowly that the voting logic stays meaningful for the life of the platform.
Installation notes
- Mount relays with contacts vertical to minimize debris accumulation
- Ensure adequate airflow to prevent condensation
- Use sealed cable glands that maintain the IP rating
- Bond earths properly for EMC
- Test annually, following classification society guidelines
For marine and offshore projects, verify environmental ratings and class society requirements before committing to a part number, and for safety-critical circuits, plan redundancy and factory acceptance testing from the start. Our engineering team works across commercial shipping, naval vessels, offshore platforms, and subsea equipment; contact [email protected] for technical support and custom configurations, or browse the HVR series and HRX series pages.