Switch For Thermocouple Wires

[Dynon101]

I do not have sufficient pins left over for my temperature monitoring needs.

One of the items I do not need to monitor on a regular basis is the turbocharger intercooler outlet temperature (the actual temperature of the air entering the engine inlet) as I just really need to see that on a very hot day.

Since this airplane is a pusher there is no visual indication of smoke or fire like on a tractor airplane so I would really like to have an internal engine cowling temperature indication using a thermocouple. I envision setting up the Skyview to trigger a red indication and a warning if a fire develops in the engine compartment and then I can react quicker than waiting for the really bad day to happen.

Since the engine inlet temperature is a NICE to know and the engine cowling is a NEED to know... I was thinking about installing the two thermocouples and then wire each pair of wires to a DPST switch and then this switch would remain in the position to sence the NEED to know information 99 percent of the time and then flicked to the NICE to know position when iy is nice to know.

Other than the usual solid connectors and quality switch requirements is there anything special to consider with thermocouple wires?

THANKS!!!

 

[Raymo]

Another option you might consider is to use a standard temperature sensor hooked to one of the "C" type inputs in the EMS. Not sure this would work with higher temps, though.

I happen to have a spare carb temp sensor and plan to use it to measure the temperature inside the Will James plenum of my RV-7A.

 

[Dynon]

If you're truly out of inputs, that would work. You don't want any temperature change across the junctions that you make. That'll show up as errors in the temperature readings.

 

[Dynon101]

>You don't want any temperature change across the junctions that you make. That'll show up as errors in the temperature readings

So as to try to insulate the thermocouple wire junctions at the switch as much as possible...Perhaps I can wrap the terminal ends that connect to the switch body terminals in heat shrink and then also wrap the switch body and wire bundle in heat shrink.

THANKS for the advice!!!

 

[planecurious]

The more typical situation that was being referred to (to avoid, with a thermocouple temperature sensor) is a connector mounted on a bulkhead such as the firewall, with one set of pins on one side of the bulkhead and the other set of pins on the other side of the bulkhead, with significantly different temperatures on each side.

Are you aware that in addition to the 12 thermocouple inputs on the 25-pin connector of the EMS module, there are also 2 thermocouple inputs on the 37-pin connector of the EMS module? If you use those 2 inputs, you would avoid the complexity, and the potential reliability issues of the switch.

 

[Dynon101]

>Are you aware that in addition to the 12 thermocouple inputs on the 25-pin connector of the EMS module, there are also 2 thermocouple inputs on the 37-pin connector of the EMS module? If you use those 2 inputs, you would avoid the complexity

THANKS for the information.. I have a turbo six banger and I need CHT and EGT for each cylinder plus I need a Turbine Inlet Temperature sensor.

How many Thermocouple inputs does the 37 pin input have?

It is a bit confusing about the A B C pins.

 

[Dynon]

There are two thermocouple inputs on the EMS D37 connector (pins 27/28 and 36/37) in addition to the 12 on the D25 connector.

 

[Dynon101]

Got it...I will use pins 27/28 for the TIT and 36/37 for the Engine Cowling

THANKS!!!