7.9 Thermocouple Inputs
YUAA reads temperature inputs from thermocouples with E, J, K, S, T, B, N, and R styles, and has open wire detection.
Source I/ O+
I/ O-
Thermocouple
I/ O+
I/ O-
Thermocouple
Input
Supported TC Types and Temperature Ranges
TC Type
Min Max
mV -40 114
Min Temp (ºF) Max Temp (ºF)
T -328 752
K -328 2501.6
J -337.38 2192
E -328 1832
S -40 3214.4
B 32 3308
N -454 2372
R -58 3214.4
Burnout detection on the input is based on a periodic pulse of current forcing the open terminal voltage outside the
normal -40 to 95 mV region. Therefore, there may be a delay of up to 1 second from the time a sensor fails to when the
burnout is detected. When the input goes open, the input terminal voltage typically drops close to zero. If the thermocouple
sensor is hotter than the YUAA screw temperature, the reported temperature reading will report colder (since the TC had been
at a positive terminal input voltage). If the thermocouple sensor is colder than the YUAA screw temperature, the temperature
reading will momentarily report a warmer temperature, until the pulsed current source causes detection of the open circuit and
the behavior specified by the ReportOpenTC parameter is applied.
Burnout Detection is only enabled on E, J ,K, S, T, B, N and R styles of thermocouples. When the ReportOpenTC parameter
is set to Fail_Cold, the YUAA will report Extrapolated values from TC tables at -40 mV (Open TC threshold). When
ReportOpenTC is set to Fail_Hot, the YUAA will report 2000 °C (3632 °F) depending on TempUnits selection. Burnout
detection is disabled on mv selection. Therefore, ± 312.5 mV can be read with mv type selection with healthy zone limited
from -40 mV to 114 mV.
192 GEH-6855_Vol_II GEH-6855_Vol_II Mark VIeS Functional Safety Systems Volume II
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