You are currently viewing MTL5575 TEMPERATURE CONVERTER


THC or RTD input + Alarm

The MTL5575 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 all thermocouple types and 2-, 3- or 4-wire RTDs. (For thermocouple applications the HAZ-CJC plug on terminals 1–3 includes an integral CJC sensor). Configuration is carried out using a personal computer. A single alarm output is provided and may be configured for high or low process alarm or to provide notice of early thermocouple failure.
See also common specification
Number of channels
Signal source
Types J, K, T, E, R, S, B or N THCs to BS 60584 and XK
EMF input
Pt 100, Pt 500, Pt 1000
2/3/4-wire platinum RTDs to BS 60751
Cu-50 & Cu-53
Ni 100/500/1000 DIN 43760
Location of signal source
Zone 0, IIC, T4-6 hazardous area
Division 1, Group A, hazardous location
Input signal range
–75 to +75mV, or 0 to 400Ω (0 to 1000Ω Pt & Ni sensors)
Input signal span
3 to 150mV, or 10 to 400Ω (10 to 1000Ω Pt & Ni sensors)
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 (500ms response)
Series mode rejection
40dB for 50Hz or 60Hz
Calibration accuracy (at 20°C)
(includes hysteresis, non-linearity and repeatability)
Inputs: (500ms response)
mV/THC: ± 15μV or ± 0.05% of input value
(whichever is greater)
RTD: ± 80mΩ
Output: ± 11μA
Temperature drift (typical)
mV/THC: ± 0.003% of input value/°C
RTD: ± 7mΩ/°C
Output: ± 0.6μA/°C
Example of calibration accuracy and temperature drift
(RTD input – 500ms response)
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
Early burnout
Early burnout detection for thermocouples (when selected)
Alarm trips when loop resistance increase is > 50Ω
Output range
4 to 20mA nominal into 600Ω max. (direct or reverse)
Alarm output
Relay ON in alarm, 250mA @ 35V max
Maximum lead resistance (THC)
Response time
Configurable – 500 ms default
(Accuracy at 100/200ms – contact MTL)
LED indicator
Green: power and status indication
Yellow: alarm indication, on when contacts are closed
Maximum current consumption (with 20mA signal)
50mA at 24V
Power dissipation within unit (with 20mA signal)
1.2W at 24V
Safety description
Refer to certificate for entity parameters. Um=253V rms or dc.s
A personal computer running MTL PCS45 software with a
PCL45USB serial interface.
THC or RTD input + Alarm
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
8 Output –ve/Alarm relay
9 Alarm relay
11 Output –ve
12 Output +ve
13 Supply –ve
14 Supply +ve

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