Omega Engineering OMB-DAQTEMP Series 사용자 설명서
3-2 Making Signal Connections
09-03-02
DaqTemp User’s Manual
For isothermal performance, an exposed, grounded copper plane surrounds the input
connectors. It is important that non-insulated input wires do not contact the grounded
plane
connectors. It is important that non-insulated input wires do not contact the grounded
plane
−−−− since such contact can degrade measurement integrity.
It should be noted that thermocouples output very small voltages and that long thermocouple leads can
pickup a large amount of noise. However, the DaqTemp modules inherently provide a high level of noise
immunity via their 4 Hz signal bandwidth and input filtering. If desired, further noise reduction can be
achieved through the use of shielded thermocouples and/or averaging.
pickup a large amount of noise. However, the DaqTemp modules inherently provide a high level of noise
immunity via their 4 Hz signal bandwidth and input filtering. If desired, further noise reduction can be
achieved through the use of shielded thermocouples and/or averaging.
You can minimize the effect of noise by (1) using shielded thermocouples,
(2) averaging readings, or (3) employing both of these practices.
(2) averaging readings, or (3) employing both of these practices.
To accommodate shielding, grounded connections, labeled “SHIELD,” are provided. A typical use of the
connection would be the attachment of the shield to a shielded thermocouple.
connection would be the attachment of the shield to a shielded thermocouple.
If a thermocouple shield is connected to a DaqTemp’s SHIELD connection,
leave the shield unconnected at the other end of the thermocouple.
leave the shield unconnected at the other end of the thermocouple.
Open Thermocouple Detection
DaqTemps are equipped with open thermocouple detection for each T/C channel. This means that a broken
thermocouple wire [or otherwise unconnected input that is measured] will result in an off-scale reading.
This is accomplished by applying a small bias current to each of the channel inputs. Whenever a valid input
is absent, the bias current saturates the input amplifier, resulting in the off-scale reading.
thermocouple wire [or otherwise unconnected input that is measured] will result in an off-scale reading.
This is accomplished by applying a small bias current to each of the channel inputs. Whenever a valid input
is absent, the bias current saturates the input amplifier, resulting in the off-scale reading.