Specifications, Derating curve – Rockwell Automation 1794-IT8_IR8 FLEX I/O 8 Thermocouple Input Module User Manual

Page 5

Publication 1794-IN021D-EN-P - August 2003

Specifications

Derating Curve

Specifications

1794-IT8

1794-IR8

Number of Inputs

8 channels

Module Location

Cat. No. 1794-TB2, -TB3, -TB3S, -TB3T and -TB3TS Terminal Base Units

Nominal Input
Ranges

-76.5 to +76.5mV

1 to 433 ohms

Supported
Thermocouple Types
(1794-IT8 only)

Type

Range °C

Range °F

300 to 1800°C

(572 to 3272°F)

0 to 2315°C

(32 to 4199°F)

-270 to 1000°C

(-454 to 1832°F)

-210 to 1200°C

(-346 to 2192°F)

-270 to 1372°C

(-454 to 2502°F)

TXK/XK(L)

-200 to 800°C

(-328 to 1472°F)

-270 to 1300°C

(-454 to 2372°F)

-50 to 1768°C

(-58 to 3214°F)

-50 to 1768°C

(-58 to 3214°F)

-270 to 400°C

(-454 to 752°F)

Supported RTDs

(1794-IR8 only)

Resistance

100

= 0.00385 Euro (-200 to +870°C)

100

= 0.003916 U.S. (-200 to +630°C)

200

= 0.00385 Euro (-200 to +400°C)

500

= 0.00385 Euro (-200 to +630°C)

100

Nickel

= 0.00618 (-60 to +250°C)

120

Nickel

= 0.00672 (-60 to +250°C)

200

Nickel

= 0.00618 (-60 to +250°C)

500

Nickel

= 0.00618 (-60 to +250°C)

Copper

= 0.00427 (-200 to +260°C)

RTD Excitation
Current

718.36

Resolution

16 bits (2.384

V typical)

16 bits across 435 ohms

Accuracy

Refer to “Calculating the Accuracy”
section in Appendix A of the user
manual (1794-UM007)

Without calibration, at low humidity:

Normal mode: 0.05% full scale (max)

Enh. mode: 0.01% full scale (typical)

Common Mode
Rejection

-115db @ 60Hz; -100db @ 50Hz

-120db @ 60Hz; -100db @ 50Hz with
A/D filter cutoff @ 10Hz

Common Mode Input
Range

+10V maximum

0V between channels (common
return)

Isolation Voltage

Tested at 850V dc for 1s from inputs and user power to logic side

Data Format

16-bit 2’s complement or offset binary (unipolar)

Normal Mode Noise
Rejection

-60db @ 60Hz

-60db @ 60Hz for A/D filter cutoff @
10Hz

Input Offset Drift
w/Temperature

+6mV/°C maximum

1.5 milliohm/°C maximum

Gain Drift w/Temp.

10ppm/°C maximum

Normal mode: 20ppm/°C max.

Enhanced mode: 10ppm/°C max.

Channel Bandwidth

0-2.62Hz (-3db)

Settling time to 100%
of final value

Available at system throughput rate

System Throughput

325ms (1 channel scanned),
programmable to 28ms

2.6s (8 channels scanned),
programmable to 224ms

Normal mode - 325ms (1 channel
scanned), programmable to 28ms

2.6s (8 channels scanned),
programmable to 224ms
Enhanced mode - programmable
from 56 to 650ms/channel - 650ms
(1 channel scanned), 2.925s (8
channels scanned)

Open TC/RTD Circuit
Detection

Out of range reading (upscale)

Open TC/RTD
Detection Time

Available at system throughput rate

Overvoltage
Capability

35V dc, 25V ac continuous at 25°C

Overall Drift with
Temperature

50ppm/°C of span (maximum)

Cold Junction
Compensation

Range: 0 to 70°C

A-B catalog number 1794-CJC2

Channel to channel
isolation

+10V

Indicators

1 red/green power status indicator

Flexbus Current

20mA

Power Dissipation

3.0W maximum @ 31.2V dc

Thermal Dissipation

Maximum 10.2 BTU/hr @ 31.2V dc

Keyswitch Position

General Specifications

External dc Power
Supply

Voltage Range

Supply Current

24V dc nominal
19.2 to 31.2V dc (includes 5% ac ripple)

19.2 to 31.2V dc for ambient temperatures < 40°C

24V dc maximum for ambient temperatures = 55°C

See derating curve

150mA @ 24V dc

Dimensions (with
module installed)

31.8H x 3.7W x 2.1D inches
45.7H x 94W x 53.3D mm

Environmental Conditions

Operating
Temperature

IEC 60068-2-1 (Test Ad, Operating Cold),
IEC 60068-2-2 (Test Bd, Operating Dry Heat),
IEC 60068-2-14 (Test Nb, Operating Thermal Shock):
0 to 55°C (32 to 131°F)

Storage
Temperature

IEC 60068-2-1 (Test Ab, Un-packaged Non-operating Cold),
IEC 60068-2-2 (Test Bb, Un-packaged Non-operating Dry Heat),
IEC 60068-2-14 (Test Na, Un-packaged Non-operating Thermal Shock):
–40 to 85°C (–40 to 185°F)

Relative Humidity

IEC 60068-2-30 (Test Db, Un-packaged Non-operating

Damp Heat):
5 to 95% non-condensing

Vibration

IEC60068-2-6 (Test Fc, Operating):
5g @ 10-500Hz

Shock

IEC60068-2-27 (Test Ea, Unpackaged shock):
Operating 30g
Non-operating 50g

Emissions

CISPR 11:
Group 1, Class A (with appropriate enclosure)

ESD Immunity

IEC 61000-4-2:
4kV contact discharges
8kV air discharges

Radiated RF
Immunity

IEC 61000-4-3:
10V/m with 1kHz sine-wave 80%AM from 30MHz to 1000MHz

EFT/B Immunity

IEC 61000-4-4:
±2kV at 5kHz on signal ports

Surge Transient
Immunity

IEC 61000-4-5:
+2kV line-earth(CM) on shielded ports

Conducted RF
Immunity

IEC 61000-4-6:
10Vrms with 1kHz sine-wave 80%AM from 150kHz to 30MHz

Enclosure Type Rating

None (open-style)

Signal Conductors

Thermocouple

Millivolt
Category

Thermocouple - Use appropriate
shielded thermocouple wire

Belden 8761

2-wire -Belden 9501

3-wire, less than 100ft with normal
humidity - Belden 9533

3-wire, greater than 100ft or normal
humidity (>55°C for > 8 hrs) - Belden
83503

Power Conductors

Wire Size