Soldering low voltage wires a nono?
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Re: Soldering low voltage wires a nono? (2point2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point2 »</TD></TR><TR><TD CLASS="quote">I was told to never solder theormocouple wires at work. Does the same rule apply to any automotive sensors?</TD></TR></TABLE>
No it doesn't. Heres why. Thermocouples work from the joining of dis-similar metals, when these metals become heated at the junction, they product an output in milivolts depending on how much heat is applied (or cold) will effect the output of these milivolts. Now with that being said, the wire that goes from the thermocouple to the Temperature Reading device (usually a PLC) must be made from the same metals as both sides of the thermocouple, the reason being, if you were to use a copper signal wire, at the point of junction between the copper signal wire and the thermocouple you would infact have another thermocouple form at that point, throwing off the signal. This is also why polarity of the wires must be kept proper. Signal wires of a thermocouple are all different based on the type of thermocouple, all - wires are RED, and then based on the colour of the positive wire you can identify the type of thermocouple you have and the type of signal wire you need.
Now that being said, thermocouples are the only thing you will ever come across that has an output voltage with heat applied (alot like an EGT sensor). Since lowvoltage sensors dont infact produce any output voltage and are mainly just a resistor of some sort, this does not apply to them, and the voltages they use will be MUCH higher then the output of a thermocouple. So when you take in to account the principals on how a thermocouple works vs. other low voltage automotive sensors, its easy to understand why you can solder different types of connections.
To join wires on a thermocouple you actually use a small 'terminal block' which actually is made up of the same kinds of metals in the thermocouple to prevent any other joining of dis-similar metals
FYI: The small coolers you get for your car, that you plug into the ash try and they can cool water and stuff, how do they work? Theres no compressor, there infact a REVERSE thermocouple, they used the idea, that if you put voltage in you get heat out, but in this case its negative voltage for negative temperature
No it doesn't. Heres why. Thermocouples work from the joining of dis-similar metals, when these metals become heated at the junction, they product an output in milivolts depending on how much heat is applied (or cold) will effect the output of these milivolts. Now with that being said, the wire that goes from the thermocouple to the Temperature Reading device (usually a PLC) must be made from the same metals as both sides of the thermocouple, the reason being, if you were to use a copper signal wire, at the point of junction between the copper signal wire and the thermocouple you would infact have another thermocouple form at that point, throwing off the signal. This is also why polarity of the wires must be kept proper. Signal wires of a thermocouple are all different based on the type of thermocouple, all - wires are RED, and then based on the colour of the positive wire you can identify the type of thermocouple you have and the type of signal wire you need.
Now that being said, thermocouples are the only thing you will ever come across that has an output voltage with heat applied (alot like an EGT sensor). Since lowvoltage sensors dont infact produce any output voltage and are mainly just a resistor of some sort, this does not apply to them, and the voltages they use will be MUCH higher then the output of a thermocouple. So when you take in to account the principals on how a thermocouple works vs. other low voltage automotive sensors, its easy to understand why you can solder different types of connections.
To join wires on a thermocouple you actually use a small 'terminal block' which actually is made up of the same kinds of metals in the thermocouple to prevent any other joining of dis-similar metals
FYI: The small coolers you get for your car, that you plug into the ash try and they can cool water and stuff, how do they work? Theres no compressor, there infact a REVERSE thermocouple, they used the idea, that if you put voltage in you get heat out, but in this case its negative voltage for negative temperature
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