Emerson Rosemount 644 with HART Protocol, Справочное руководство

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72
Reference Manual
00809-0200-4728, Rev SA
Troubleshooting
July 2018
Troubleshooting
Table 5-2. Standard RTD vs. RTD with Matched CVD Constants with Enhanced Transmitter
Accuracy Option P8
Callendar-Van Dusen equation:
The following input variables, included with specially-ordered Rosemount temperature sensors, are
required:
R
t
= R
o
+ R
o
a [t – d(0.01t-1)(0.01t) – b(0.01t – 1)(0.01t)
3
]
R
0
= Resistance at ice point
Alpha = Sensor specific constant
Beta = Sensor specific constant
Delta = Sensor specific constant
To input Callendar-Van Dusen constants, perform one the following procedures:
Field Communicator
From the HOME screen, enter the Fast Key sequence.
Table 5-1. Standard RTD vs. RTD with Matched CVD Constants with Standard Transmitter Accuracy
System accuracy comparison at 150 °C using a PT 100 (
α
=0.00385)
RTD with a span of 0 to 200 °C
Standard RTD Matched RTD
Rosemount 644 ±0.15 °C Rosemount 644 ±0.15 °C
Standard RTD ±1.05 °C Matched RTD ±0.18 °C
Total System
(1)
1. Calculated using root-summed-squared (RSS) statistical method.
±1.06 °C Total System
(1)
±0.23 °C
System Accuracy Comparison at 150 °C Using a PT 100 (
α
=0.00385)
RTD with a Span of 0 to 200 °C
Standard RTD Matched RTD
Rosemount 644 ±0.10 °C Rosemount 644 ±0.10 °C
Standard RTD ±1.05 °C Matched RTD ±0.18 °C
Total System
(1)
1. Calculated using root-summed-squared (RSS) statistical method
±1.05 °C Total System
(1)
±0.21 °C
Device Dashboard Fast Keys
2, 2, 1, 9
TotalSystemAccuracy TransmitterAccuracy
( )
2
SensorAccuracy
( )
2
+ =
TotalSystemAccuracy TransmitterAccuracy
( ) 2
SensorAccuracy
( ) 2
+ =