Rolls-Royce R129646A Voltage Transmitter Assembly

Rolls-Royce R129646A Voltage Transmitter

The Rolls-Royce R129646A Voltage Transmitter Assembly is an instrumentation module designed for critical power generation, switchgear distribution, and propulsion automation systems. Engineered to withstand severe shipboard vibration, electromagnetic interference, and thermal cycling, this transducer samples single-phase or three-phase alternating voltages and converts them into linear, galvanically isolated DC current signals (typically 4–20 mA) for marine Power Management Systems (PMS), Alarm Monitoring Systems (AMS), and automated generator synchronizers.

Model Details

• Manufacturer: Rolls-Royce Marine / Kongsberg Maritime
• Model Designation: R129646A
• Manufacturer Part Number (MPN): R129646A
• Associated Family Code: Series R-TX-VT Marine Instrumentation

Technical Details

Features

1. Three-Port Galvanic Isolation: 2.5 kV AC isolation across sensing input, DC output loop, and auxiliary power supplies eliminates ground loops in marine switchboards.
2. True RMS Measurement Architecture: Delivers class 0.5 measurement accuracy even in dirty electrical networks distorted by variable frequency drives (VFDs) and non-linear loads.
3. Ruggedized Enclosure & Conformal Coating: Vibration-rated DIN-rail housing with MIL-I-46058C conformal coating on internal PCBs prevents corrosion from salt fog and engine-room condensation.
4. Transient & Surge Immunity: High surge withstand capability exceeding IEC 61000-4-5 requirements, shielding delicate automation I/O cards from generator breaker switching transients.
5. Wide Operating Bandwidth: Factory-calibrated for 50 Hz, 60 Hz, and 400 Hz marine electrical grids with drift rates under 0.1% per year.

Applications

• Main and emergency marine switchboard busbar voltage monitoring.
• Diesel generator automatic voltage regulation (AVR) feedback loops.
• Generator synchronization and auto-paralleling automation racks.
• Shaft generator and hybrid electric propulsion drive monitoring.
• Bow thruster switchgear and shore connection monitoring panels.

Compatibility

• Automation Systems: Rolls-Royce Common Automation System (CAS), Rolls-Royce Helicon-X, Kongsberg K-Chief 600 / K-Chief 700, and Kongsberg AutoChief.
• Propulsion Units: Rolls-Royce Ulstein Aquamaster azimuth thrusters, Kamewa tunnel thrusters, and Bergen diesel propulsion suites.
• Switchboards & Synchronizers: Marine main switchboards integrating Woodward, DEIF, and Schneider Electric load-sharing controllers.

Part Number Cross-References

• Rolls-Royce Direct Variant: R984672B
• Rolls-Royce Alternate Revision: R984672C
• Internal Reference / Alang Yards Ref: POT-03037195

Frequently Asked Questions

What is the primary function of the Rolls-Royce R129646A Voltage Transmitter?

The R129646A measures high-voltage AC potentials across shipboard generator sets or distribution busbars, providing a galvanically isolated 4–20 mA DC current signal for engine control systems, PMS automation, and switchboard instrumentation.

Can the R129646A be used directly without a potential transformer (PT)?

Direct measurement depends on the system voltage variant. While low-voltage models can measure up to rated line voltage directly, 440V and 690V main busbars typically feed the unit through instrument-grade potential transformers (e.g., 440:110V or 690:110V) for safety and accuracy. Always check the serial badge markings on the chassis.

Are R129646A and R984672B interchangeable?

R129646A and R984672B share the same mounting footprint, form factor, and standard marine automation protocol, but may differ in factory zero/span settings or input attenuation steps. Cross-verify the exact input voltage span on the equipment nameplate prior to hot swapping.

What causes a 0 mA reading from an installed R129646A unit?

A 0 mA reading typically indicates a loss of 24V DC auxiliary excitation, an open-circuit fault in the 4–20 mA output cable loop, a blown internal safety fuse, or an unseated terminal connector.

How is the R129646A calibrated during scheduled maintenance?

Calibration is verified using a precision AC voltage source and a calibrated 5.5-digit multimeter in series with the current loop. Zero is checked at 0V AC input (outputting exactly 4.00 mA), and span is checked at nominal 100% rated input (outputting exactly 20.00 mA). Small deviations can be corrected via the onboard multi-turn potentiometers.