Technical data

Publication 1794-2.1 - January 2000
FLEX I/O and FLEX Integra Product Data
24V dc Thermocouple/mV Input Module Cat. No. 1794-IT8 131
Derating Curve
Specifications - 1794-IT8
Number of Inputs 8 Channels
Module Location Cat. No. 1794-TB3T, -TB3, -TB3S, -TB2, or -TB3TS
Terminal Base Unit
1
Nominal Input
Voltage Ranges
±76.5mV
Supported
Thermocouple Types
Type B: 300 to 1800
o
C (572 to 3272
o
F)
Type C: 0 to 2315
o
C (32 to 4199
o
F)
Type E: -270 to 1000
o
C (-454 to 1832
o
F)
Type J: -210 to 1200
o
C (-346 to 2192
o
F)
Type K: -270 to 1372
o
C (-454 to 2502
o
F)
Type N: -270 to 1300
o
C (-454 to 2372
o
F)
Type R: -50 to 1768
o
C (-58 to 3214
o
F)
Type S: -50 to 1768
o
C (-58 to 3214
o
F)
Type T: -270 to 400
o
C (-454 to 752
o
F)
Type TXK/XK (L): -200 to 800
o
C (-328 to 1472
o
F)
Resolution 16 bits (2.384 µV typical)
Accuracy with filter
@ 24
o
C (±0.5
o
C)
0.025% Full Scale Range maximum
Accuracy without filter
@ 24
o
C (±0.5
o
C)
0.05% Full Scale Range maximum
Data Format 16-bit 2’s complement or offset binary (unipolar)
Normal Mode
Noise Rejection
-60db @ 60Hz
Common Mode Rejection -115db @ 60Hz; -100db @ 50Hz
Common Mode
Input Range
+10V maximum
Channel to
Channel Isolation
+
10V
System Throughput 325ms (1 channel scanned),
programmable to 28ms
2.6s (8 channels scanned),
programmable to 224ms
Settling Time to 100% of final
value
Available at system throughput rate
Open Circuit Detection Out of range reading (upscale)
Open Thermocouple
Detection Time
Available at system throughput rate
Overvoltage Capability
35V dc, 25V ac continuous @ 25
o
C
250V peak transient
Channel Bandwidth 0 to 2.62Hz (-3db)
RFI Immunity Error of less than 1% of range at 10V/M
27 to 1000MHz
Input Offset Drift
With Temperature
+
6 µV/
o
C maximum
Gain Drift
With Temperature
10ppm/
o
C maximum
Overall Drift
With Temperature
50ppm/
o
C of span (maximum)
Cold Junction Compensation
Range
0 to 70
o
C
Cold
Junction Compensator
Kit Cat. No. 1794-CJC2 (contains 2 CJCs)
Indicators 1 red/green power/status indicator
Flexbus Current 20mA
Power Dissipation 3W maximum @ 31.2V dc
Thermal Dissipation Maximum 10.2 BTU/hr @ 31.2V dc
Keyswitch Position 3
General Specifications
External dc Power
Supply Voltage
Voltage Range
Supply Current
24V dc nominal
19.2 to 31.2V dc (includes 5% ac ripple)
19.2V dc for ambient temperatures < 55
o
C
24V dc for ambient temperatures < 55
o
C
31.2V dc for ambient temperatures < 40
o
C
See derating curve.
150mA @ 24V dc
Dimensions HxWxD 1.8mm x 3.7mm x 2.1mm (46in x 94in x 53in)
Environmental Conditions
Operational Temperature
Storage Temperature
Relative Humidity
Shock Operating
Non-operating
Vibration
0 to 55
o
C (32 to 131
o
F) See derating curve.
-40 to 85
o
C (-40 to 185
o
F)
5 to 95% noncondensing (operating)
5 to 80% noncondensing (nonoperating)
30 g peak acceleration, 11(±1)ms pulse width
50 g peak acceleration, 11(±1)ms pulse width
Tested 5 g @ 10-500Hz per IEC 68-2-6
Publications
Installation Instructions
User Manual
1794-5.21
1794-6.5.7
Agency Certification
1 Use a 1794-TB3, -TB3S, or -TB2 terminal base unit for mV inputs only. You must use a
1794-TB3T and -TB3TS terminal base unit when using thermocouple inputs.
Class I Division 2 certified
Groups A, B, C, D certified
Class I Zone 2 Group IIC certified
User Applied 24V dc Supply
19.2
31.2
24.0
0
o
C25
o
C40
o
C50
o
C55
o
C
Ambient Temperature
Safe operating area
The area within the curve represents the safe operating range for the module
under various conditions of user supplied 24V dc supply voltages and
ambient temperatures.
40156