Controller keeps watch over Mexican gas production

Edited by the Engineeringtalk editorial team May 10, 2004

EPG Companies has installed radio telemetry Scada systems to monitor 24 Pemex remote natural gas production sites in rural Villa Hermosa, Mexico.

EPG Companies has installed radio telemetry Scada systems to monitor 24 Pemex remote natural gas production sites in rural Villa Hermosa, Mexico.

This particular project involved using radio telemetry to monitor remote gas production sites.

The operators needed a central PC to retrieve the production data, view site status, and perform shutdowns.

NBT, the telemetry division of EPG Companies, designed, documented, assembled, programmed, and tested the complete system in the factory.

Just 5 weeks after receipt of the order, NBT shipped a complete, turnkey Scada system that matched the customer�s specifications.

Once received, the mostly Spanish-speaking engineers used the provided documentation to install and start up the entire system.

The Scada PC was also set up and started without on-site factory support.

A typical system is comprised of a PC master station, which is a manned site, and 25-30 remote stations located within a 55km radius of the PC master station.

Each system uses NBT SM800 controllers with AGA3 gas calculations for flow monitoring.

Each controller is capable of supporting up to four flows as well as numerous other digital and analogue I/O requirements.

The units communicate (Modbus) with the master PC via 9600 baud, 480MHz radios.

The PC master station uses HMI (human machine interface) software to display flow rates, flow totals and alarm/status information points on a continuous, near real-time fashion.

Excel reports are generated to summarise production figures.

An entire years production can be recorded in a single Excel workbook.

Key flow information is also recorded in the remote station's controller on an hourly basis.

This information is available as backup in the event of a catastrophic loss of the master or interruptions in the communications facilities.

The SM800 combines the functionality of a data logger, a programmable logic controller, and a communications controller into one powerful, cost-effective unit.

With this PLC-RTU, users can check conditions, perform control or reprogram anytime, from any location and any alarm or event can trigger a call to a PC, fax or pager.

It can be used for one or multiple sites.

The SM800 continuously tracks performance of any equipment or process over an extended period of time.

The unit stores 5600 events (22,000 optional) including a date and time stamp and data can be transferred into Microsoft Excel, Access or any DDE compatible software.

The SM800 allows users to monitor various points in a single piece of equipment, a complex process, or a complete facility.

Users can perform real-time control and/or program the unit to control any point in the system as well as have the control based on arithmetic calculations such as min/max totalisation, run times etc.

Every unit has three communication ports: two standard RS232 and either a RS485, RS422, RS232, a telephone or a radio modem.

This allows the SM800 to be configured in a system within a hierarchical network in which remote units can communicate with each other as intelligent nodes on a network.

The peer-to-peer capability allows remote units to call out to other units on a timed basis and/or alarm condition.

When user defined problems are detected, the SM800 can call up to six numbers including a PC, fax, and pager.

Local display is optional and provides flows, temperatures etc.

Additional options include dial-up and spread spectrum radio communications.

The Pemex system has been in and running without a glitch.

There have been no system problems related to the telemetry equipment.

Other gas production monitoring systems are in varying stages of completion.

The scope of these additional systems has increased, now including automatic report generation, increased point counts, four additional systems and over 250 newly installed RTU units.

NBT systems are engineered for remote environments.

All equipment supplied is specifically designed for field applications and through testing, ensures less maintenance and downtime.

Most systems integrate bits and pieces of hardware and software from different sources.

This is normally required to meet the varying specifications between systems.

NBT equipment has the built-in flexibility and functionality to fulfil the requirements of virtually any system.

Additionally, all NBT products feature an industry standard Modbus protocol, which ensures open connectivity to any existing or new systems.