The thermocouple
pre-amplifiers are aimed at the simultaneous measurement of external
package and/or PWB temperatures during thermal transient testing.
They are provided for an easy interfacing of J, K or T type
thermocouples to the Main System Unit. The amplifiers have a cold
point compensation and provide an output voltage range matched to
the measurement channels of T3Ster®.
The power supply of the amplifiers is provided from the Main System
Unit through the measurement channel connectors.
Certain types of one-point IR sensors (such as Cole-Parmer P-39669-0x
series) provide output signal compatible with thermocouples, that
is, they can be also connected to the T3Ster®
equipment using our thermocouple pre-amplifiers.
aNo
thermocouple included
bIndicate
the thermocouple type in your order
cWithout
the cable connecting to the Main System Unit
DETAILED
SPECIFICATIONS
Built-in cold junction compensation
(suppression
of Tcold_junct: 26 dB)
Thermocouple types: K or T or Ja,
b
Output voltage: 100 mV at 25 °C
Cut-off frequency: 800 Hz
Input resistance: 2kW
Noise equivalent temperature error: ±0.015 °C
Sensitivity: 4 mV/°C ±1%
at room temperature
(matched
to the 400 mV range for 0..100 °C of T3Ster®)
Powering: by T3Ster Main System Unit
( via
the cable connection to a measurement channel)
Sizec (w x d x h): 80 mm x 61 mm
x 22 mm
Comments:
Thermocouples tend to operate as an antenna - collecting
electro-magnetic noise from the environment. In steady-state
measurements such EM noise cancels out by the long term
averaging of the measurement but in case of transient measurements
they are inherently present in the measured results. In
order to avoid measuring electro-magnetic noise the following
rules of thumb need to be kept:
Thermocouple wires should be as short as possible.
If there is no shield around the thermocouple the wire
length should be below 250 mm. This is not a limitation
on thermocouple location, the output cable can be sufficiently
long.
It is advised to use protective shield around longer
thermocouples. The shielding should be connected to
the Shield socket of the thermocouple connector inside
the amplifier.
The electrical resistance of the thermocouple should not
exceed 10-15 W otherwise measurement
results will be of lower accuracy.
The pre-amplifier can be used only with the type of the
thermocouple indicated on the cover of the amplifier (J,
K or T).
Thermocouples must be connected to the amplifier with
the right polarity such that the T3Ster Main System Unit
would measure increasing voltage with increasing temperature,
otherwise the ice-point compensation would fail.
For proper operation of the ice-point compensation the
temperature of the amplifier should be kept in the range
of 15..35 °C.
The relationship between the thermocouple temperature
and voltage is weakly non-linear. The pre-amplifier provides
an optimal linear approximation.
Thermal time-constant range: Typical thermocouples have a
thermal time-constant in the order of magnitude 10 ms (20..40 ms,
very fast ones of 5 ms). That is why thermal transients captured via
thermocouples in the time range between 1 µs and cca. 10 ms
carry no valuable information.
