IMI STI SmarTrak ST Hydraulic Positioning Controller

IMI STI SmarTrak ST digital controller for hydraulic positioning

The IMI STI SmarTrak ST is an electronic positioning controller for hydraulic actuators that are driven by proportional solenoid valves. It receives a 4-20 mA command, compares it with the measured actuator position and drives the proportional valve with a PWM signal until the two agree. Seven Star LLC supplies the SmarTrak ST in Oman and the GCC as an independent supplier in Muscat, and this page explains the model code and the practical points to settle before an enquiry.

One controller can serve up to two independent actuators. The manufacturer positions the unit as a way to avoid expensive closed-loop proportional valves: the intelligence sits in the SmarTrak ST, so simpler proportional valves can be used on the actuator. Typical use is in power generation, oil and gas and other heavy industry, where hydraulic actuators move large valves or dampers.

Decoding the SmarTrak ST model code

The model selection sheet for the ST2 version builds the order code from six choices. Each position is listed below exactly as the manufacturer defines it.

Drawing numbers shown as dots on the sheet are project specific, so confirm them with the manufacturer. The sheet does not give a single complete example code, so please send us the required option for each position and we will confirm the resulting configuration.

SmarTrak ST technical specifications

How the SmarTrak ST controls a hydraulic actuator

The controller closes the position loop electronically. The position of the actuator is read through a transducer, converted by the integrated position transmitter, and compared with the 4-20 mA set point. The difference becomes a PWM output to the proportional solenoid valve, which meters hydraulic oil to the actuator. With a loop time of 1 ms, the controller can correct quickly, which is useful for fast strokes.

The auto-tuning function adjusts the control parameters for the installed actuator, so commissioning does not rely on trial and error with a screwdriver. The self-diagnosis function watches the unit and its connections, and the digital outputs can pass status to the plant control system. A trip function is also available through digital inputs.

Where the SmarTrak ST fits in the hydraulic system

The SmarTrak ST belongs to the family of IMI STI positioners and sits between the plant control system and the hydraulic power unit and actuator. It is not a pneumatic positioner. For air-operated actuators IMI STI offers other products, such as the SA-1 analog positioner covered elsewhere in the catalogue. Where two valves or dampers share one hydraulic skid, the ability to run two independent actuators from one enclosure reduces cabinet count and wiring.

Selection and ordering checklist for the SmarTrak ST

• Number of actuators to control: one or two.
• Housing: standard, stainless steel, hazardous or special, and whether stainless steel is wanted for coastal or offshore sites.
• Supply voltage available: universal AC / 110 Vdc, or 24 Vdc.
• Communication needs: digital I/O only, or CANBUS and 485/422 as well.
• Local display or blind cover.
• Certification route: UL or CE, and the hazardous area classification of the installation.
• Type of proportional valve and position transducer on the actuator.
• Whether the remote monitoring software is to be used on the plant network.

Installation, commissioning and maintenance of the SmarTrak ST

Mount the enclosure where it is protected from direct mechanical damage and from vibration at the actuator. Although the housing is IP66, cable glands must be correctly sealed to keep that rating. Keep the signal cable separate from power cables and terminate the shields as the instruction manual describes.

Commissioning starts with checking the supply and the 4-20 mA signal, then running the auto-tuning routine with the hydraulic system at normal operating pressure. Save the final parameter set through the USB port or the remote software and keep a copy with the loop documents. For maintenance, log diagnostic messages, inspect terminals and fuses at shutdowns, and keep a spare controller board or complete unit for critical valves. The manufacturer publishes an instruction manual for the SmarTrak ST, and you should work from the revision that matches your unit.

Typical SmarTrak ST applications in Oman and the GCC

Hydraulic actuation is common on turbine control and stop valves, large dampers, and valves that need high thrust and tight speed control. In Oman and the wider Gulf these appear in gas-fired power and water plants, oil and gas production and processing, and petrochemical units. High ambient temperatures, dust and humidity make the IP66 housing and the stainless steel option relevant, and long cable runs make the digital communication options worth considering early.

Information to send with a SmarTrak ST RFQ

• Part number SmarTrak ST and quantity.
• Required code for each of the six positions in the table above.
• Actuator type, stroke and the proportional valve in use.
• Supply voltage and communication protocol.
• Area classification and certification requirement.
• Delivery location in Oman or the GCC.

Documents and quotation

The manufacturer model selection datasheet for the SmarTrak ST is attached on this page. It lists the option codes summarised above.

To request a quotation, send the part number, quantity and the option for each code position, and we will confirm the configuration and lead time.