SCT1P34
Linearized 2- or 3-Wire RTD Input Transmitters
FEATURES
DESCRIPTION
● INTERFACES TO 100Ω PLATINUM OR 120Ω NICKEL RTDs
Each SCT1P34 RTD input transmitter provides a single channel of RTD input
which is filtered, isolated, amplified, linearized, and converted to a process
current output (Figure 1). Signal filtering is accomplished with a six-pole
filter which provides 95dB of normal-mode-rejection at 60Hz and 90dB at
50Hz. Two poles of this filter are on the input side of the isolation barrier, and
the other four are on the process loop side. After the initial field-side filtering,
the input signal is chopped by a proprietary chopper circuit. Isolation is
provided by transformer coupling, again using a proprietary technique to
suppress transmission of common mode spikes or surges.
● LINEARIZES RTD SIGNAL
● PROCESS CURRENT OUTPUT
● 1500Vrms TRANSFORMER ISOLATION
● ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION
● INPUT AND OUTPUT PROTECTED TO 240VAC CONTINUOUS
● UP TO 100V LOOP VOLTAGE
RTD excitation is provided from the transmitter by two matched current
sources. When using a three-wire RTD, this method allows an equal current
to flow in each RTD lead, which cancels the effects of lead resistances. The
excitation currents are very small (0.25mA) which minimizes self-heating of
the RTD.
● 160dB CMR
● 95dB NMR AT 60Hz, 90dB at 50Hz
● ±0.02% CONFORMITY
Special input and output circuits on the SCT1P34 transmitters provide
protection against accidental connection of power-line voltages up to 240VAC
and against transient events as defined by ANSI/IEEE C37.90.1-1989.
Transmitter zero and span settings are adjustable up to ±10%. The adjustments
are made using potentiometers located under the access plate on the top of
the transmitter housing and are non-interactive for ease of use.
● CSA CERTIFICATION AND FM APPROVAL PENDING
● CE COMPLIANT
Isolation
Barrier
3- and 4-wire(1) 2-wire
+EXC
4
+In
RTD
3
–In
2
–EXC
1
Surge
Suppression RZ
and
Protection
LPF
Iso-Chopper™
Amplifier
Pat Pending
LPF
Surge
Suppression
and
Protection
Linearizer
NC
+VL
–VL
–Vf
–Vf
Isolated
Field-Side
Power
Power
Oscillator
Note:
(1) 4-wire sensors may be used with this transmitter.
However, for true 4-wire measurement, contact the factory.
Fig 1: SCT1P34 Block Diagram
®
Loop-Side
Power
–Vf
+Vf
A Burr-Brown Company
–LOOP
5
4-wire(1)
DATAFORTH
+LOOP
6
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168
SPECIFICATIONS Typical at T = +25°C and +24V loop voltage
A
Transmitter
SCT1P34
Input Range
-200°C to +850°C (100ΩPt)
-80°C to +320°C (120ΩNi)
Input Resistance
Normal
Power Off
Overload
Input Protection
Continuous
Transient
Sensor Excitation Current
Lead Resistance Effect
CMV, Input to Output
Continuous
Transient
CMR (50Hz or 60Hz)
NMR
50MΩ
90kΩ
90kΩ
240Vrms max
ANSI/IEEE C37.90.1-1989
0.25mA
±0.02°C/Ω
1500Vrms max
ANSI/IEEE C37.90.1-1989
160dB
95dB at 60Hz, 90dB at 50Hz
±10% zero and span
See Ordering Information
±0.02%
Adjustability
Accuracy
Conformity Error(2)
Stability
Offset
Gain
Noise
Output, 100kHz
Bandwidth, –3dB
Response Time, 90% Span
50ppm/°C
100ppm/°C
3µArms
4Hz
165ms
Output Range
Output Limits
Under-range
Over-range
Output Protection
Reverse Polarity
Over-voltage
Transient
Loop Supply Voltage
Loop Supply Sensitivity
Turn-On Delay
4mA to 20mA
2.5mA
28mA
Continuous
240Vrms continuous
ANSI/IEEE C37.90.1-1989
10.8V to 100V
±0.0005%/V
400ms
Environmental
Operating Temp. Range
Storage Temp. Range
Relative Humidity
RFI Susceptibility
–40°C to +85°C
–40°C to +85°C
0 to 95% Noncondensing
±0.5% Span Error at 400MHz, 5W, 3ft
Mechanical Dimensions
NOTES:
2.98" dia x 1.67" height
(75.7mm x 42.4mm)
**RTD STANDARDS
TYPE
ALPHA COEFFICIENT
100Ω Pt
120Ω Ni
0.00385
0.00672
DIN
JIS
DIN 43760
JIS C 1604-1989
(1) Includes conformity, hysteresis, and repeatability.
(2) Adjustment of transmitter zero and span degrades conformity.
MODEL*
100ΩPt **
SCT1P34-01
SCT1P34-02
SCT1P34-03
SCT1P34-04
SCT1P34-05
120ΩNi **
SCT1P34N-01
INPUT RANGE
ACCURACY (1)(2)
-100°C to +100°C (-148°F to +212°F)
0°C to +100°C (+32°F to +212°F)
0°C to +200°C (+32°F to +392°F)
0°C to +600°C (+32°F to +1112°F)
0°C to +400°C (+32°F to +752°F)
±0.20˚C
±0.10˚C
±0.20˚C
±0.60˚C
±0.40˚C
0°C to +300°C (+32°F to +572°F)
SCT1P
ORDERING INFORMATION
±0.30˚C
* True 4-wire input and other RTD types available upon request.
169
Call 800-444-7644
For Information and Assistance
DATAFORTH
A Burr-Brown Company
®