The BULLET is energized from the 4 mA … 20 mA current loop, using a special technology called “StepVolt”. This technology allows users to set insertion voltage from 1 V to 2.5 V in order to optimize the use of available loop power and wireless communication bandwidth. The BULLET provides reliable performance even under worst case low-current conditions, where there is very little power available – when using transmitters on very long cable runs or with intrinsically safe barriers. In scenarios where more power is available, the BULLET provides more WirelessHART packets per second, leading to an increased performance of the overall WirelessHART network.
A unique feature of the BULLET is its ability to multidrop up to eight HART measurement devices using a single BULLET. This digital multidrop feature drives down the cost of adding devices to an existing WirelessHART network: No linking device, special wire, power conditioners, segment terminators, or additonal training for personnel are needed. This cost-effective feature is especially useful for many SCADA applications including the monitoring of tank farms and pipelines.
The fill levels of 23 tanks containing petrochemicals need to be reliably monitored. From a cost perspective, adding new measuring devices is challenging, as the tanks are spread out over a distance and the control cabinet is tightly packed with cabling. The BULLET offers a highly cost-efficient solution: the multidrop feature allows operators to address up to eight field devices on a tank with just one of these Ex d WirelessHART adapters.
As the plant already uses a 24 V supply (lighting e.g.), the adapter and field device can be powered by this supply and wirelessly transfer data to the process control system. For best possible signal transmission, BULLETS are mounted on poles 2 meters high above the tank.
In this outdoor application at a chemical plant, the BULLET is used for detection of possible gas leakage. Several “trees”, each holding five BULLETS, are positioned across the plant for comprehensive monitoring of the fence line. Each portable tree contains four gas meters for detection of different gas types, a propeller that measures wind speed, and a fin that measures wind direction. Among this total of six measured signals are four 4…20 mA and two HART signals.
Due to the multidrop feature, the two HART devices are connected to a single BULLET. Both signal types, 4…20 mA and HART, are reliably and completely wirelessly transferred to the control system via BULLETS—even at ambient temperatures of -33 °C. In this setup, the BULLETS draw energy from a solar loop, as each tree is equipped with a solar panel in conjunction with a battery pack.
Mobile gas detection units enable the customer to detect gas almost anywhere at the plant. A mobile gas detection unit consists of a gas meter, a solar panel and additional battery for power supply, a control box, and a BULLET. The BULLET draws energy from the solar panel and transmits 4 mA … 20 mA signals from the gas meter to the control system.
WirelessHART devices like the BULLET build a mesh network: the signals are passed on from one BULLET to another or directly to a WirelessHART gateway that interacts with the control system. Operators can easily build up a highly flexible communication structure inside the plant.
Flexibility is needed in state-of-the-art pharmaceutical applications: here, portable mixing tanks are a routine part of drug production and handle all relevant processing steps—from mixing to heating and cooling of the product. Each portable mixing tank is equipped with several field devices. A total of two BULLETS (one running in multidrop mode) transfers four HART transmitter signals (level, PH, temperature, pressure) and one 4…20 mA signal (motor speed controller) to the WirelessHART gateway which interacts with the control system.
The BULLET draws energy from the AC power supply of the agitator's motor, keeping the wireless data transmission independent from restrictions of batteries or extra power supplies. With its rugged housing, the BULLET also easily withstands the stress of typical Clean-in-Place (CIP) procedures.
Get to know the widest portfolio of WirelessHART adapters in the market! Product Marketing Manager Sabrina Weiland introduces several types of adapters and advises which one is the best fit for your application.