Wireless transmission of I/O data in the field

Safe and inexpensive wireless connection for BP in Ohio

  • Optimal wireless system for decentralized plants with a range of up to 32 kilometers
  • Modular system with high IT security
  • Also suitable for large mesh networks with up to 250 devices

Wireless pilot project for BP in Ohio

BP operates numerous refineries in the USA.

Engineers and technicians started a wireless pilot project at the location in Ohio. They wanted to find out whether reliable wireless data transmission is possible in an environment that is exposed to extreme electromagnetic interference.

Application

The objective was to avoid high cabling costs that arise due to storage tanks located at large distances from each other.

High-voltage cables with strong interference fields lie near the wireless paths. Their effect on the transmission quality needed to be examined. Additionally aggravating was the fact that the oil tank sites do not have their own power supply.

A remote groundwater pump was selected as the test object.

Here, the level had to be measured and, once a limit value was reached, an alarm emitted. The pump uses ultrasound to determine the level and converts it into an analog signal. When the upper limit value is reached, a threshold value switch also generates a digital alarm signal.

Solution

A wireless transmission system from Phoenix Contact was installed on the pump. This enabled I/O data to be acquired wirelessly in the field and the information to be forwarded to a controller via an RS-232 interface.

Up to eight analog and digital extension modules can be connected per station, and can therefore be selected accordingly for the relevant application. On the control side, information from one (point-to-point) or several (multipoint-to-point) field stations can be evaluated via Modbus protocol.

Up to 255 field stations can be operated on one master. All hardware is supplied autonomously via a solar system with solar panels, battery, and charge controller.

Summary

The wireless connection worked remarkably reliably in this environment subjected to strong electromagnetic interference.

The cost benefits were also analyzed: cabling the system would have involved digging up the ground to lay cables over a distance of approximately 700 meters. BP assumed a cost of approximately €80 per meter in this specific case. Overall, it was possible to save more than €56,000.

After the positive tests, the BP Group has integrated the wireless transmission systems from Phoenix Contact into the production facility on the Ohio River. A total of 16 crude oil tanks were equipped.