High Performance Signal Conditioners DSCA
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DSCA34
Linearized 2- or 3-Wire RTD Input Signal Conditioners
Description
Each DSCA34 RTD input module provides a single channel of RTD input which
is filtered, isolated, amplified, linearized, and converted to a high level voltage
output. Signal filtering is accomplished with a five-pole filter which provides 85dB
of normal-mode-rejection at 60Hz and 80dB at 50Hz. An anti-aliasing pole is
located on the field side of the isolation barrier, and the other four poles are on
the system 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.
RTD excitation is provided from the module using a precision current source.
Lead compensation is achieved by matching two current paths which cancels
the effects of lead resistance. The excitation current is small ( approx. 0.25mA)
which minimizes self-heating of the RTD.
Module output is either voltage or current. For current output models a dedicated
loop supply is provided at terminal 3 (+OUT) with loop return located at terminal
4 (-OUT). The system-side load may be either floating or grounded.
Special input circuits 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. Protection circuits are also present on the signal output
and power input terminals to guard against transient events and power reversal.
Signal and power lines are secured to the module using screw terminals which
are in pluggable terminal blocks for ease of system assembly and reconfiguration.
The modules have excellent stability over time and do not require recalibration,
however, zero and span settings are adjustable up to ±3% to accomodate
situations where fine-tuning is desired. The adjustments are made using
potentiometers located under the front panel label and are non-interactive for
ease of use.
Figure 1: DSCA34 Block Diagram
Features
Interfaces to 100Ω Platinum or 120Ω
Nickel RTDs
Linearizes RTD Signal
Industry Standard Output of either 0-10V,
0-20mA, or 4-20mA
1500Vrms Transformer Isolation
ANSI/IEEE C37.90.1-1989 Transient
Protection
Input Protected to 240VAC Continuous
True 3-Way Isolation
Wide Range of Supply Voltage
160dB CMR
85dB NMR at 60Hz, 80dB at 50Hz
±0.08% Accuracy
±0.025% Conformity
Easily Mounts on Standard DIN Rail
CSA and FM Approvals Pending
CE Compliant
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Specifications
Input Range Limits -200°C to +850°C (100Ω Pt)
-80°C to +320°C (120Ω Ni)
Input Protection
Continuous 240Vrms max
Transient ANSI/IEEE C37.90.1-1989
Sensor Excitation Current ≈ 250µA
Lead Resistance Effect +0.02°C/Ω
Output Range See Ordering Information
Load Resistance (IOUT) 600Ω max
Current Limit 8mA (VOUT), 30mA (IOUT)
Output Protection
Short to Ground Continuous
Transient ANSI/IEEE C37.90.1-1989
CMV, Input to Output, Input to Power
Continuous 1500Vrms max
Transient ANSI/IEEE C37.90.1-1989
CMV, Output to Power
Continuous 50VDC max
CMR (50Hz or 60Hz) 160dB
Accuracy See Ordering Information
Conformity ±0.025% (100Ω Pt)
±0.07% (120Ω Ni)
Adjustability ±3% zero and span
Stability
Input Offset ±1µV/°C
Output Offset ±6ppm/°C (VOUT), ±20ppm/°C (IOUT)
Gain ±60ppm/°C
Output Noise, 100kHz Bandwidth 250µVrms (VOUT), 1µArms (IOUT)
Bandwidth, 3dB 3Hz
NMR 85dB at 60Hz, 80dB at 50Hz
Response Time, 90% Span 250ms
Power Supply
Voltage 15 to 30VDC
Current 25mA (VOUT), 45mA (IOUT)
Sensitivity ±0.0001%/%
Protection
Reverse Polarity Continuous
Transient ANSI/IEEE C37.90.1-1989
Environmental
Operating Temp. Range 40°C to +80°C
Storage Temp. Range 40°C to +80°C
Relative Humidity 0 to 95% Noncondensing
Emissions EN50081-1, ISM Group 1, Class A
(Radiated, Conducted)
Immunity EN50082-1, ISM Group 1, Class A
(ESD, RF, EFT)
Mechanical Dimensions 2.95" x 0.89" x 4.13"
(h)(w)(d) (75mm x 22.5mm x 105mm)
Mounting DIN EN 50022 -35x7.5 or -35x15 rail
Module DSCA34
Typical at TA=+25°C and +24V supply voltage Ordering Information
Model
100ΩΩ
ΩΩ
Ω Pt **
DSCA34-01 -100°C to +100°C 2, 3, 4 ±0.08% ±0.16°C
(-148°F to +212°F)
DSCA34-02 0°C to +100°C 2, 3, 4 ±0.10% ±0.10°C
(+32°F to +212°F)
DSCA34-03 0°C to +200°C 2, 3, 4 ±0.08% ±0.16°C
(+32°F to +392°F)
DSCA34-04 0°C to +600°C 2, 3, 4 ±0.05% ±0.30°C
(+32°F to +1112°F)
DSCA34-05 -50°C to +350°C 2, 3, 4 ±0.05% ±0.20°C
(-58°F to +662°F)
120ΩΩ
ΩΩ
Ω Ni **
DSCA34N-01 0°C to +300°C 2, 3, 4 ±0.15% ±0.45°C
(+32°F to +572°F)
Input Range Output Accuracy1
Range
**RTD Standards
Type Alpha Coefficient DIN JIS
100Ω Pt 0.00385 DIN 43760 JIS C 1604-1989
120Ω Ni 0.00672
Output Range Part No. Suffix Example
1. -10V to +10V NONE NA
2. 0V to +10V NONE DSCA34-01
3. 4 to 20mA C DSCA34-01C
4. 0 to 20mA E DSCA34-01E
Output Ranges Available
NOTES:
(1) Includes conformity, hysteresis and repeatability.
