Masoneilan Remote Position Sensor (RPS) for SVI II AP, SVI3 and SVI FF

Overview

The Masoneilan Remote Position Sensor, often abbreviated RPS, is a remotely mounted position-sensing device that Baker Hughes supplies for digital valve positioners and other suitable field devices. It reports the stem or shaft position of a valve through a rotary transducer in its own enclosure, so that the electronics of the positioner can be located away from the valve itself. Baker Hughes lists the typical reasons for doing this as extreme vibration, heat or radiation, which are conditions in which a positioner mounted directly on the actuator would be at risk.

Seven Star LLC is a trusted supplier for Masoneilan and supplies the Masoneilan Remote Position Sensor to customers in Oman and across the GCC who run SVI II AP, SVI3 or SVI FF positioners. The quick start guide, revision D, covers all three, and our Muscat instrumentation team can confirm the lever, bracket and cable arrangement for each valve before a kit is ordered.

Operating Principle of the Masoneilan Remote Position Sensor

A precision rotary transducer inside the Masoneilan Remote Position Sensor housing turns with the output shaft. Baker Hughes specifies a potentiometer with rotation and no mechanical stops, and a resistance of 1 kOhm. The unit is connected by three wires on a spring pressure terminal block: high, wiper and low. The positioner reads this potentiometer as valve position in place of its own internal sensor, so the control loop is closed on the remote measurement.

On a reciprocating valve the stem motion is carried by a take-off rod to a lever through a turnbuckle, and the lever turns the shaft. The lever must stay within an angular range of plus and minus 50 degrees about the centre, with the lever at the 0 degree position when the valve is at mid-travel. On a rotary valve a valve-side lever with a pin engages a slot in the lever on the sensor, and an anti-backlash spring takes up play. The guide gives a resistance check between the red and brown terminals, with the cable disconnected, to confirm that the potentiometer is in range.

Engineering Design of the Masoneilan Remote Position Sensor

The housing and cover of the Masoneilan Remote Position Sensor are cast to ASTM B85 and the output shaft and fasteners are austenitic stainless steel, with silicone O-rings. The complete unit weighs 1.6 kg (3.5 lb). It is suitable for installation indoors and outdoors in an industrial environment, and mounting kits are available to fit a variety of valves. Standard Masoneilan mounting kits accommodate linear travel from 6.35 mm (0.25 in) to 63.5 mm (2.5 in), and rotary travel is limited to 100 degrees.

Installing the Masoneilan Remote Position Sensor uses ordinary hand tools: an adjustable wrench, hex keys, a blade screwdriver and a nut driver. For reciprocating valves the guide tabulates the mounting hole, lever hole and turnbuckle length by actuator size and stroke, for example turnbuckle lengths of 1.25 in, 2.90 in and 5.25 in for Masoneilan actuator sizes 10, 16 and 23. The cable should be shielded and up to 14 AWG, and the guide recommends no more than 25 m between the sensor and the positioner, with the factory to be consulted beyond 30 m.

Key Features

The following points explain why the Masoneilan Remote Position Sensor is chosen for harsh locations:

• It separates position sensing from the positioner electronics, which protects the electronics from heat, vibration and radiation at the valve.
• One sensor works with the Masoneilan SVI3, SVI II AP and SVI FF positioners, and it can also be used with non-Masoneilan positioners.
• Operating temperature is -50 degC to +125 degC in non-hazardous classified locations and -50 degC to +85 degC in hazardous environments.
• The three-wire connection is colour coded, with black as low, brown as wiper, red as high and the shield as ground.
• Reciprocating and rotary mounting procedures are both documented, with tables for Masoneilan actuator sizes 6, 10, 16 and 23.
• The potentiometer has no mechanical stops, so the lever must be restricted to the angular range shown in the guide.
• Raw sensor counts can be checked in the positioner software or on a handheld, which confirms the minimum and maximum positions.
• Configuration for the SVI II AP and SVI3 is carried out in the DTM, and for the SVI FF in the DTM or through function blocks.

Industrial Applications

The Masoneilan Remote Position Sensor belongs on valves where the environment is too severe for a positioner on the yoke. Baker Hughes names vibration, heat and radiation as the typical reasons. In Oman such conditions can arise in power and desalination plants along the Batinah coast, in gas processing facilities and in refinery units at Sohar and Duqm, where the positioner can be placed in a more benign location while the sensor stays with the valve.

In Oman and the GCC, Seven Star LLC supplies the Masoneilan Remote Position Sensor with the positioners it serves, including the Masoneilan SVI3 digital valve positioner and the Masoneilan SVI FF valve positioner, and with the Masoneilan Type 87/88 actuators on which the reciprocating kit is fitted. Our engineers will check the hazardous area approval of the positioner, which for the remote sensor is covered by documents ES-787, ES-817 and ES-776.

Technical Specifications

The table summarises the published data for the Masoneilan Remote Position Sensor from the Baker Hughes quick start guide, revision D.

Related Masoneilan positioners and instruments include the Masoneilan SVI II AP digital valve positioner, Masoneilan SVi1000 digital valve positioner and Masoneilan SVI II ESD digital valve positioner.

Request a Quote for Masoneilan Remote Position Sensor

To request pricing or technical support for the Masoneilan Remote Position Sensor, send a formal RFQ to the Seven Star LLC instrumentation division with the positioner model, the valve and actuator type, the stroke or rotation and the cable length. We can confirm the mounting arrangement, advise on availability and lead time and provide the Baker Hughes quick start guide from this page. In Oman and the GCC, Seven Star LLC delivers genuine products with manufacturer documentation and local engineering support.