Technical specifications for MTL5074

Description

The MTL5074 converts a low-level dc signal from a temperature sensor
mounted in a hazardous area into a 4/20mA current for driving a
safe-area load. Software selectable features include linearisation,
ranging, monitoring, testing and tagging for eight thermocouple
types and 2-, 3- or 4-wire RTDs. For thermocouples requiring coldjunction compensation, the HAZ-CJC plug can be ordered with the
product, and includes an integral CJC sensor.
SPECIFICATION
See also common specification
Number of channels
One
Signal source
Types J, K, T, E, R, S, B or N THCs to BS 4937
EMF input
2/3/4-wire platinum RTDs to BS 1904/DIN43760 (100Ω at 0°C)
Location of signal source
Zone 0, IIC, T4 hazardous area
Div.1, Group A, hazardous location
Input signal range
–75 to +75mV, or 0 to 400Ω (Input impedance 10MΩ)
Input signal span
3 to 150mV, or 10 to 400Ω
RTD excitation current
200µA nominal
Cold junction compensation
Automatic or selectable
Cold junction compensation error
≤1.0°C
Common mode rejection
120dB for 240V at 50Hz or 60Hz
Series mode rejection
40dB for 50Hz or 60Hz
Calibration accuracy (at 20°C)
(includes hysteresis, non-linearity and repeatability)
Inputs:
mV/THC: ±15µV or ±0.05% of input value
(whichever is greater)
RTD: ±80mΩ
Output: ±11µA
Temperature drift (typical)
Inputs:
mV/THC: ±0.003% of input value/°C
RTD: ±7mΩ/°C
Output: ±0.6µA/°C
Example of calibration accuracy and temperature drift
(RTD input)
Span: 250Ω
Accuracy: ± (0.08/250 + 11/16000) x 100%
=0.1% of span
Temperature drift: ± (0.007/250 x 16000 + 0.6) µA/°C
= ±1.0µA/°C
Safety drive on sensor burnout
Upscale, downscale, or off
Output range
4 to 20mA nominal (direct or reverse)
Maximum load resistance
600Ω
LED indicator
Green: one provided for power and status indication
Power requirement, Vs with 20mA signal
68mA at 24V
82mA at 20V
52mA at 35V
Power dissipation within unit with 20mA signal
1.5W at 24V
1.6W at 35V
Terminal Function
1 THC/EMF/RTD input –ve
3 THC/EMF/RTD input +ve
4 3-wire RTD input –ve
5 4-wire RTD input +ve
11 Output –ve
12 Output +ve
13 Supply –ve
14 Supply +ve

Isolation
250V ac between safe- and hazardous-area circuits and power
supply
Safety description
Terminals 1 and 3
i) Without CJ plug
Vout = 1.1V
Iout = 7mA
Pout = 2mW
Non-energy-storing apparatus ≤1.2V, ≤0.1A, ≤20µJ and ≤25mW.
Can be connected without further certification into any IS loop
with open-circuit voltage not more than 10V.
ii) With CJ plug
Vout = 6.6V, Iout = 10mA
Pout = 17mW
Terminals 1 and 3, 4 and 5
Vout = 6.6V, Iout = 76mA, Pout = 0.13W
Configuration socket (CON6)
Vout = 8.3V, Iout = 15mA, Pout = 26mW
Standard configuration
Input type RTD, 3-wire
Linearisation enabled
CJ Compensation disabled
Units °C
Damping/Smoothing value 0 seconds/0 seconds
Output zero 0°C
Output span 250°C
Tag and description fields blank
Open circuit alarm set high (upscale)
Transmitter failure alarm set low (downscale)
CJ failure alarm set low (downscale)
Line frequency 50Hz
Configurator
A personal computer running MTL PCS45 software with a PCL45
interface.
TO ORDER, specify:
MTL5074 Includes HAZ-CJC signal plug (with internal CJC
sensor). For use with thermocouple, mV or RTD inputs.
MTL5074-RTD Includes standard HAZ1-3 signal plug. For use
with mV or RTD inputs. (Can be used with
thermocouples with cold-junction compensation if
HAZ-CJC plug is fitted.)
HAZ-CJC Hazardous-area signal plug for terminals 1 to 3
including cold-junction compensation sensor.