Question
How does grounding the thermoelectric cooler cable on temperature controllers affect the noise level?
Answer
If the cable connecting the thermoelectric cooler (TEC) and sensor to the temperature controller is not properly grounded, it can allow the sensor wires inside to pick up noise. When the cable is grounded, it isolates the sensor wires from environmental noise. When ungrounded, there is no noise protection for the sensor wires, allowing them to pick up surrounding electrical noise.
To avoid this issue, simply ground the TEC cable by bending the exposed wire (no colored sheath) backwards, such that when the metal case is put onto the end, the wire will make physical contact with the metal case. The metal case then makes physical contact with the chassis (which is grounded) through the screws that attach the plug to the unit. This ensures that, through physical contact, the TEC cable is properly grounded.
Bend the exposed wire backwards (away from the connector).
When the case is put back on, ensure that there is contact between the case and the wire.
For example, during IntelliTune® testing, stability measurements were taken around 15°C with the TC LAB instrument. The graphs below show the effect of having the TEC cable ungrounded and properly grounded. By grounding the TEC cable, electronic noise in this measurement is reduced by approximately 40%.
TEC Cable Shield Ungrounded
TEC Cable Shield Properly Grounded