ESC caught fire during preflight checklist

[landedit]

Hello all, I recently built a twin edf engine plane. However, while running over the preflight checklist I did an engine check and my esc's both started smoking furiously.

Both engines were the same, the were the 64mm EDF Viggen package from grayson hobby. Why did they catch fire? I was using a 3S battery and the ESC's were both rated for 60A.

-Curious Arsonist

 

[nhk750]

Im thinking, fans spinning wrong direction? I new to edf so I will watch this thread.

 

[quorneng]

If both the ESC started smoking then the most likely issue is they were either over loaded or under cooled or both!
A Watt meter would tell you how much current each motor is actually drawing.
How much airflow is there over the ESCs when running stationary on the ground?
Remember an ESC creates virtually as much heat as the motor but it does not have the benefit of it going round fast to help stir the air about so ensuring the heat generated by an ESC requires specific attention.
To make matters worse you may well have damaged (cooked!) the ESCs,

 

[nhk750]

Yes, im thinking more, possibly ran them static too long? Shouldnt static test for more than 30 sec or so without good airflow on the electronics.

 

[TazRC]

Another possibility: I had an EDF smoke a more-than-capable ESC because the blades were hitting the EDF housing (causing the motor to draw twice the Current). It also puffed the battery.

 

[Hai-Lee]

The only times I have seen a esc fire in a twin were,

The owner got confused and fitted a 4S battery to a 3S design both ESCs "Smoked" whilst taxiing to the end of the runway!

Builder used a "Y" harness to connect the 2 ESCs but inserted one of them the wrong way around. Nothing worked! Whilst trying to fault find the issue one of the ESCs got extremely hot and failed catastrophically causing a wiring fire which went all the way as burning wiring melted through the ESC heatshrink and shorted out the components on the ESC. Second fire!

He ripped the battery out, (it took a few goes as it was also very hot) the Rx and servos seem to have survived but the battery resembled a avocado.

Final incident was a design that had about 4 or so flights under its belt when during one pass the plane did not seem to be flying quite as well so the pilot closed and then slammed the throttles wide open and smoke ensued. The ESCs were 20A driving a 20A load with very poor ventilation over time the ESCs were almost barbecued until one shut down from temp and then it seems that when the ESC cooled just a little and the motor was enabled again the throttle being slammed must have caused a current or voltage spike which fried both ESCs.

The simple ESC rule is to De-rate if cooling is poor. He fitted a pair of 35A ESCs and improved the airflow over them and now has zero problems.

Just the past!

Have fun!