Table of Contents
Advertisement
6 .7 .5
Single channel, mV/THC input for low power signals
The MTL5581 takes a low-level dc signal from a voltage source in a hazardous area, isolates it,
and passes it to a receiving instrument located in the safe area. The module is intended for use
with thermocouples utilising external cold-junction compensation. A switch enables or disables
the safety drive in the event of thermocouple burnout or a cable breakage; a second switch
permits the selection of upscale or downscale operation as the application requires.
MTL5581
PWR
Figure 6 .31:
Top label
for MTL5581
Please note that the safety drive on the MTL5581 responds to a line breakage (i.e. an open circuit)
or a thermocouple burnout. It does not provide detection of a short circuit. It can however, when
chosen, be set to drive the output either upscale or downscale. These options are selected using
the switches located on the side of the module.
* Within V
Drive direction '+' Upscale '–' Downscale
54
MTL5581 - mV/Thermocouple Isolator
Hazardous area
mV
Terminal
Function
1
THC/mV input –ve
2
THC/mV input +ve
11
Output –ve
12
Output +ve
13
Supply –ve
14
Supply +ve
Safety drive switches
Sw2
Sw1
Safety drive
Drive direction
OFF
OFF
ON
ON
ON
ON
/V
transfer accuracy and drift error as specified in the product datasheet.
in
out
Safety drive switches
Sw1
OFF
Safe area
6
7
5
8
4
9
mV
10
3
+
–
11
2
mV
12
1
+
–
13
14
20 to 35V dc
Line
breakage
N/A
NO
N/A
YES
+
NO
+
YES
–
NO
–
YES
Sw 1
Sw 2
ON
Sw2
Safety drive
* Use compensating
cable with
thermocouple inputs
Output*
Vs–
Vs+
V
out value
V
*
in
undetermined
V
*
in
> +50mV
V
*
in
< –50mV
OFF position
ON position
OFF
ON
OFF
ON
INM 5500 Rev 10
Hide quick links:
Advertisement
Table of Contents
