Instructions

UM-0085-B09 DT80 Range User Manual Page 319
RG
Temperature – RTDs
Resistance Temperature Detectors are sensors generally made from a pure (or lightly doped) metal whose electrical
resistance increases with temperature. Provided that the element is not mechanically stressed and is not contaminated
by impurities, the devices are stable, reliable and accurate.
Channel Types
The DT80 supports four RTD types:
Channel Type
Metal
Default 0 °C ohms
Alpha
Standard
PT385
Platinum
100
0.003850
DIN43760 (European)
PT392
Platinum 100 0.003916 JIS C1604 (American)
NI
Nickel
1000
0.005001
CU
Copper
100
0.00390
The alpha is defined by:
 =




100 

//
where Ro is the resistance at 0°C and R100 is the resistance at 100°C.
The 0°C resistance is assumed to be 100  for platinum (P
specified as a channel option.
Channel Options
The following channel options are useful with RTD channel types:
•
3W, 4W can be used to select the wiring configuration, as with any resistance measurement
•
I, II can be used to set the excitation. For the Platinum and Copper RTDs, the II (2.5mA) option (which is
the default) should normally be used, to provide good measurement resolution for the relatively low resistance
value being measured. If self-heating is a concern, the I (200µA) excitation option can also be used. For the
higher resistance Nickel type,
I (200µA) is the default.
• the channel factor is the 0°C value of the RTD, e.g. 100 for a PT100 sensor. The default value for each type is
shown in the table above.
For example,
PT385(4W,50)
reads a 4-wire 50Ω (at 0°C) device.
Temperature – AD590 Series IC Sensors
AD590 series sensors are 2-terminal semiconductor devices which produce a current that is proportional to absolute
temperature. This makes them useful with long lead lengths. Supply voltage is typically 4-30V.
Channel Types
The following channel types are supported. All operate identically.
Channel Type
Description
Range
AD590
1µA / K
-55 – +105 °C
AD592
1µA / K
-25 – +105 °C
TMP17
1µA / K
-40 – +105 °C
Channel Options
The following channel options are sometimes used when measuring AD590 series devices:
• the excitation options specify how the sensor is powered:
V (use internal 4.5V voltage source; default), E
(external supply connected to EXT* terminal) or
N (external supply).
•
MDn (measurement delay) specifies that the DT80 should wait n ms (default 10ms) after selecting a channel
before starting the actual measurement. This can be useful in conjunction with the
E or V option, as it allows the
sensor some time to stabilise after power is applied to it.
• the channel factor specifies the shunt resistance in ohms (default 100.0 Ω), as for current measurements
•
GLx, ESn, as for voltage measurements