EMS Earth options

compnz

New Member
Joined
Aug 14, 2008
Messages
10
Location
New Zealand
Can all black earth wires go direct to an earth block and all sensor earth wires to a firewall forward earth block or do the sensors need to be earthed inside the EMS.
many thanks
 

Dynon

Dynon Staff
Staff member
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Jan 14, 2013
Messages
14,217
Location
Woodinville, WA
Strictly speaking, it shouldn't matter. But, like many things, the devil is in the details. The thing you're most concerned about with good grounding ensuring that your grounding point is truly ground and doesn't have voltage fluctuations or offsets. The place where we've seen this the most historically are with sensors, like oil temperature, that use the engine case itself as the ground path. There have been some cases where the engine case, though it's a big piece of metal, doesn't have a REALLY robust connection to the aircraft's overall ground, and that causes the engine's ground to be different than the rest of the electrical system's (SkyView is much more robust against this behavior than the D10/D100 series, for what it's worth).

So to answer your question, if you run an actual black ground wires from the EMS module to a sensor instead of an intermediate grounding block, you're minimizing the chances of having a hard to diagnose grounding issue. On the other hand, a well-designed ground block that's truly the same ground as the rest of the electrical system and doesn't have any odd loads going through it or other things that can cause ground points to be "not really ground" will also work.
 
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