Emerson Rosemount 8750W - Introduction; Safety Messages

139
Reference Manual
00809-0300-4750, Rev CA
Digital Signal Processing
March 2016
Digital Signal Processing
Section 7 Digital Signal Processing
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 139
Safety messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 139
Process noise profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 140
High process noise diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 140
Optimizing flow reading in noisy applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 141
Explanation of signal processing algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 145
7.1 Introduction
Magmeters are used in applications that can create noisy flow readings. The Rosemount
™
8750W Magnetic Flowmeter has the capability to deal with difficult applications that have
previously manifested themselves in a noisy output signal. In addition to selecting a higher
coil drive frequency (37 Hz vs. 5 Hz) to isolate the flow signal from the process noise, the
Rosemount 8750W microprocessor has digital signal processing capable of rejecting the
noise specific to the application. This section explains the different types of process noise,
provides instructions for optimizing the flow reading in noisy applications, and provides a
detailed description of the digital signal processing functionality.
7.2 Safety messages
Instructions and procedures in this section may require special precautions to ensure the
safety of the personnel performing the operations. Read the following safety messages
before performing any operation described in this section.
Explosions could result in death or serious injury.
 Verify the operating atmosphere of the sensor and transmitter is consistent with
the appropriate hazardous locations certifications.
 Do not remove transmitter cover in explosive atmospheres when the circuit is
alive.
 Before connecting a HART
®
-based communicator in an explosive atmosphere,
make sure the instruments in the loop are installed in accordance with
intrinsically safe or non-incendive field wiring practices.
Failure to follow safe installation and servicing guidelines could result in death or
serious injury.
 Make sure only qualified personnel perform the installation.
 Do not perform any service other than those contained in this manual unless
qualified.
 Process leaks could result in death or serious injury.
High voltage that may be present on leads could cause electrical shock.
 Avoid contact with leads and terminals.