Archive for category Level Transmitters
Our level products manufacturers have released several new instruments to make your measurement tasks easier, more efficient, and more effective. So, we’ve put together a new Lesman Level Products catalog to introduce you to the latest technology.
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Written by: Dan Weise
Siemens’ LUT 400 saves data values and alarm events in text-formatted log files. This note covers how to get the files out of the LUT400 to view them in spreadsheet format using Siemens Log Importer macro for Excel.
The text files are extracted from the LUT400 over a USB cable (mini B type connector). When the USB cable is connected to your PC, the LUT400 appears as a removable drive (circled in red, below)
Recently, we’ve run into a few radar level applications that had some startup challenges, mostly because the person installing the transmitter didn’t consider how radar wave transmission would affect the level transmitter’s performance.
One trick to any installation is to reduce the number of obstructions encountered by the transmitter. But you have to take into consideration that radar waves don’t transmit in a concentric circle around the transmitter. And this can create a problem of its own.
Recently, a refinery customer came to use with a level application. Our team determined that it would be a perfect fit for radar level gauges, IF they turned on a Siemens radar algorithm called CLEF, that would let the radar measure accurately all the way to the bottom of the tank.
What is CLEF? How does it work? And why does it matter?
Before I talk about the value of a universal 4-20mA analog output on a level controller, let me explain why anyone would care. It’s all about ground loops.
Since the early days of electronic instrumentation, way back when, even before cell phones or PCs, instrument people struggled with ground loops that create an offset error, drive the signal off scale, or burn up an analog circuit.
Lots of people like the pushbuttons on industrial pressure transmitters because the basic settings that every transmitter needs can be set up without a HART communicator. This includes things like the tag name, engineering units, LRV (Lower Range Value, the zero, or what 4.0mA represents), URV (Upper Range Value, the span, or what 20.0mA represents) and damping (an average or filter factor that dampens noise).
On the new Honeywell ST700/ST800 series smart transmitters, the tag name and engineering units are easy to configure and self explanatory, but I seem to stumble when setting up the LRV and URV because I’m faced with a non-descript choice. There’s two sets of options (under Transmitter Setup, not Calibration):
OK, either configures an LRV or a URV value, but which is which? What’s the difference?
A customer who had had lots of experience with Milltronics and Siemens ultrasonics was installing his first SITRANS LR560 radar level transmitter. They had worked with it in the shop beforehand, going through most of the settings. They even tested it by setting it up to shoot against a file cabinet and used a tape measure the check the indicated distance value.
Everything checked out OK in the shop.
When they installed the transmitter on the top of the bin, they changed the transmitter’s sensor mode parameter from the distance mode they used in the shop for testing to level mode. After aiming, the level value shown in the local display was dead nuts on, but the 4-20mA signal going back to the control room was way off.
The bin was a third full. The 4-20mA showed it about double that. Not only that, the 4-20 was going in the wrong direction. The bin was emptying and the HMI reported an increasing level value. Someone realized that an inverse-acting output was typical of a distance value, so they reconfigured the sensor mode to distance. That got the 4-20mA much closer to a distance value, but it was still not exactly what it should be, and besides, the goal was to read level, not distance, in the control room. What was going on?