Emerson Rosemount 751 User manual

Reference Manual
00809-0100-4378, Rev CF
May 2022
Rosemount™ 751 Field Signal Indicator

Safety messages
NOTICE
Read this manual before working with the product. For personal and system safety, and for optimum product performance,
ensure you thoroughly understand the contents before installing, using, or maintaining this product.
For equipment and service needs, contact your local Emerson representative or go to Emerson.com.
CAUTION
The products described in this document are NOT designed for nuclear-qualified applications. Using non-nuclear qualified
products in applications that require nuclear-qualified hardware or products may cause inaccurate readings. For information on
Rosemount nuclear-qualified products, contact your local Emerson Sales Representative.
For information on Rosemount nuclear-qualified products, contact your local Emerson Sales Representative.
2

Contents
Chapter 1 Introduction.............................................................................................................. 5
1.1 Product overview.........................................................................................................................5
1.2 LCD display.................................................................................................................................. 5
1.3 Service support............................................................................................................................6
1.4 Product recycling/disposal...........................................................................................................6
Chapter 2 Installation.................................................................................................................7
2.1 Assembly..................................................................................................................................... 7
2.2 Wiring diagrams.......................................................................................................................... 8
2.3 LCD display configuration.......................................................................................................... 12
Chapter 3 Ordering information, specifications, and drawings................................................. 17
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Contents Reference Manual
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1 Introduction
1.1 Product overview
The Rosemount 751 Field Signal Signal Indicators provide a means of displaying important
process variables. These devices operate with any two-wire transmitter that measures
input variables such as pressure, flow, liquid level, or temperature. Rosemount indicators
are ideal for installations where an integral meter would be difficult to view.
Rosemount 751 Indicators are designed for use in industrial environments where all-
weather performance is necessary. These units are vibration- and corrosion-resistant, and
explosion-proof or intrinsically safe. An LCD display or analog meter may be ordered to
meet specific application requirements.
1.2 LCD display
The LCD display requires an analog 4–20 mA dc output from a two-wire transmitter. It may
be configured from a 4 mA point of –999 to 1000 and a 20 mA point of -999 to 9999. The
sum of the 4 mA point and the span must not exceed 9999. The decimal point can be
placed in any of three positions (X.X.X.X) or not used. Calibration adjustments are made
using noninteractive zero and span buttons. The scaled meter may be labelled with the
appropriate engineering units. A twenty-segment bar graph, on the bottom of the meter
faceplate, represents the 4–20 mA signal directly.
The large 2¼-in. meter face has ½-inch high characters for easy readability as shown in
Figure 1-1. The 4 and 20 mA points may be changed by pressing the buttons on the meter
faceplate. The meter can be rotated in 90-degree increments within the enclosure for
convenient viewing.
Figure 1-1: LCD Display
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1.3 Service support
To expedite the return process, refer to Emerson.com and contact the nearest Emerson
representative.
CAUTION
Individuals who handle products exposed to a hazardous substance can avoid injury if they
are informed of and understand the hazard. Returned products must include a copy of the
required Safety Data Sheet (SDS) for each substance.
Emerson representatives will explain the additional information and procedures necessary
to return goods exposed to hazardous substances.
1.4 Product recycling/disposal
Consider recycling equipment and packaging. Dispose of the product and packaging in
accordance with local and national legislation.
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2 Installation
2.1 Assembly
The Rosemount 751 Field Signal Indicator is comprised of the components shown in
Figure 2-1. The housing may contain an analog or liquid crystal display (LCD) display
meter. Both meters are independent of component parts and are completely
interchangeable. Both meters plug into the terminal screws on the housing, as shown in
Figure 2-1.
The meter sub-assembly contains the components shown in Figure 2-2.
Figure 2-1: Rosemount 751 Exploded View
A
BC
DE
FG
H
I
J
K
L
M
N
A. Terminal screws
B. Housing O-ring
C. Field wiring terminals
D. Loop protection diode
E. Tapped mounting boss
F. Optional mounting bracket
G. Mounting bolt with washer
H. U-bolt for 2-in. pipe
I. Housing
J. Optional ¾- to ½-in. conduit reducing bushing (if required)
K. Meter
L. Bushing
M. Foam spacer
N. Housing cover
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Figure 2-2: Meter Exploded View
A
B
C
D
K
J
I
H
G
F
E
A. Retaining straps
B. Mounting screw into housing
C. Washer for retaining strap
D. Mounting screws into mounting plate
E. Terminal screws (2)
F. Mounting plate
G. Spacer plate
H. LCD display
I. Bushing
J. Foam spacer
K. Configuration buttons
2.2 Wiring diagrams
Use the following wiring diagrams to wire the Rosemount 751 Field Signal Indicator, in
series or in parallel, with Rosemount transmitters. Use shielded cable for best results in
electrically noisy environments.
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Series configuration
It is recommended that the Rosemount 751 Indicator be wired in a series configuration
when the 4-20 mA transmitter does not contain a test terminal. The indicator is designed
so the analog or LCD display meter can be removed from the housing without impacting
the integrity of the 4-20 mA loop. Removal of the entire device from the series
configuration will disrupt the loop.
Figure 2-3: Rosemount 751 Series Wiring Diagrams for Rosemount 3144P and 2051
+−
A B
C
3144P
+
−
751
+−
A B
C
2051
+−T
751
+
−
4–20 mA dc Input Signal for Rosemount 3144P 4–20 dc Input Signal for Rosemount 2051
A. Power supply
B. Load resistor
C. Optional ground
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Figure 2-4: Rosemount 751 Series Wiring Diagrams for Rosemount 3051C and 3051S
4–20 mA dc Input Signal for Rosemount 3144P 4–20 dc Input Signal for Rosemount 2051
+−
A B
C
751
+
−
3051C
+−T
+−
AB
C
751
+
−
3051S + −T
4–20 mA dc Input Signal for Rosemount 3051C 4–20 dc Input Signal for Rosemount 3051S
A. Power supply
B. Load resistor
C. Optional ground
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Parallel configuration
It is recommended that the device be wired in a parallel configuration when the 4-20 mA
transmitter includes a test terminal. Utilization of the test terminal is required in a parallel
configuration. Connecting the indicator across the positive and negative terminals of the
4-20 mA transmitter could impact the loop.
A parallel configuration will allow the removal of the indicator without affecting the
integrity of the 4-20 mA loop. Additionally, spare indicators can be added without
disrupting the loop.
Figure 2-5: Rosemount 751 Parallel Wiring Diagrams for Rosemont 3144P and 2051
A
+-
B
C
-
+
T
3144P
-+
751
A
+ -
B
C
+-T2051
751
- +
4–20 mA dc Input Signal for Rosemount 3051C 4–20 dc Input Signal for Rosemount 3051S
A. Power supply
B. Load resistor
C. Optional ground
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Figure 2-6: Rosemount 751 Parallel Wiring Diagrams for Rosemount 3051C and
3051S
4–20 mA dc Input Signal for Rosemount 3144P 4–20 dc Input Signal for Rosemount 2051
A
+-
BC
+-T
3051C
751
-+
+-
A
B
C
+-T 3051S
- +
751
4–20 mA dc Input Signal for Rosemount 3051C 4–20 dc Input Signal for Rosemount 3051S
A. Power supply
B. Load resistor
C. Optional ground
2.3 LCD display configuration
The 20-segment bar graph is factory calibrated and represents 4–20 mA directly, but the
end points of the LCD display are user-definable. The meter requires a current between 4
and 20 mA in order to be scaled, but the actual value of the current is not significant.
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2.3.1 Remove the cover
WARNING
Explosions could result in death or serious injury. Do not remove the transmitter cover in
explosive atmospheres when the circuit is live.
Procedure
Unscrew and remove the transparent housing cover from the LCD display body.
Note
The LCD display time-out is approximately 16 seconds. If you do not press the
configuration buttons within 16 seconds, the indicator will revert to reading the current
signal.
2.3.2 Position the decimal point and select the meter function
Procedure
1. Press the left and right configuration buttons simultaneously and release them
immediately.
2. To move the decimal point to the desired location, press the left configuration
button.
Note
The decimal point wraps around.
3. To scroll through the mode options, press the right configuration button repeatedly
until the meter displays the desired mode (see Table 2-1).
Note
The LCD display time-out is approximately 16 seconds. If you do not press the
configuration buttons within 16 seconds, the indicator will revert to reading the
current signal.
Table 2-1: LCD Display Mode Options
Options Relationship between Input Signal and
Digital Display
Lin Linear
LinF Linear with 5-second filter
Srt Square root
SrtF Square root with 5-second filter
Square root function only relates to the digital display. The bar graph output remains linear
with the current signal.
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Table 2-1: LCD Display Mode Options (continued)
Options Relationship between Input Signal and
Digital Display
Square root response
The digital display will be proportional to the square root of the input current where 4 mA =
0 and 20 mA = 1.0, scaled per the calibration procedure. The transition point from linear to
square root is at 25 percent of full scale flow.
Filter response operates upon “present input” and “input received in the previous five
second interval” in the following manner:
Display = (0.75 previous input) + (0.25 present input)
This relationship is maintained provided that the previous reading minus the present
reading is less than 25 percent of full scale.
2.3.3 Store the information
Procedure
Press both configuration buttons simultaneously for two seconds.
Note
The meter displays “- -” for approximately 7.5 seconds while the information is being
stored.
2.3.4 Set the display equivalent to a 4 mA signal
Procedure
1. Press the left configuration button for two seconds.
2. To decrease the display numbers, press the left configuration button. To increase
the numbers, press the right configuration button. Set the numbers between –999
and 1000.
3. To store the information, simultaneously press both configuration buttons for two
seconds.
2.3.5 Set the display equivalent to a 20 mA signal
Procedure
1. Press the right configuration button for two seconds.
2. To decrease the display numbers, press the left configuration button. To increase
the numbers, press the right configuration button. Set the numbers between –999
and 9999.
Note
The sum of the 4 mA point and the span must not exceed 9999.
3. To store the information, simultaneously press both configuration buttons for two
seconds. The LCD display meter is now configured.
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2.3.6 Replace the cover
Procedure
Make sure the rubber gasket is seated properly, and thread the transparent housing cover
onto the LCD display meter body.
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3 Ordering information, specifications,
and drawings
To view current Rosemount 751 ordering information, specifications, and drawings, follow
these steps:
Procedure
1. Go to Emerson.com/Rosemount/Rosemount 751 Field Signal Indicator.
2. Scroll as needed to the green menu bar and click Documents & Drawings.
3. For installation drawings, click Drawings & Schematics and select the appropriate
document.
4. For ordering information, specifications, and dimensional drawings, click Data
Sheets & Bulletins and select the appropriate Product Data Sheet.
5. For the Declaration of Conformity, click Certificates & Approvals and select the most
current document.
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00809-0100-4378
Rev. CF
2022
For more information: www.emerson.com
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Emerson family of companies. All other marks are the property
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