Recommended fuse/breaker for Skyview system

[ggerhardt]

Hi all,

Recently, I did the battery test (said it was time). After this, I went on a cross country flight thinking this would be a good time to get it charged back up. About 15min after take off, Skyview indicated it had lost power. Confused initially, but then realized the 5A breaker had tripped. I have a standard 1 screen system with EMS, ADAHRS and ADSB, three knob panel was using autopilot. Also, I was using the new wifi adapter to connect my iPad.

I was able to reset the breaker in a couple min. It tripped once again about 10mon later, again, reset it and then it was good for the rest of the trip (2hrs). It would appear that, when charging, the 5A breaker is not enough, for my configuration.

You guys recommend a 5a breaker, but it looks close when charging. Is it possible the wifi adapter is pushing it over the limit?

Thanks.

Geoff

 

[Carl_Froehlich]

Dynon specs say 3.5amps for the display and 1.5amps to charge the battery. It sounds like your 5amp breaker is doing exactly what it was designed to do.

I use a 5amp breaker for each display but I'm not using the Dynon battery (plane has separate and switchable power systems). If I was using the Dynon battery I'd use a 7.5 amp breaker.

Carl
RV-10

 

[dynonsupport]

Geoff,
You should never need more than a 5A breaker on SkyView.

We're actually in the process of revising the manuals to show more accurate current draws. The old number of 3.5A and 1.5A for charging is really conservative. Unless you have an amazing number of modules hooked to SkyView, you're screen is drawing about 2.5A and the charging is an additional 1A. There is plenty of overhead for a 5A circuit protector.

The WiFi module draws only about 10mA from the airplane, so the chance you were that close is very slim.

If you are reliably popping a 5A breaker, there's really two possibilities- your SkyView is somehow acting up and has something wrong, or your breaker is popping early. Breakers do wear out and fail, so that's not unreasonable.

If possible, your best troubleshooting step is to measure the current drawn through the breaker to find which device has an issue. You do need to do this with a low battery in SkyView as there is a possibility that the issue is in the charging circuit in SkyView and only draws excess power when charging a very low battery.

 

[GalinHdz]

So for:

2ea  D7
2ea ADAHRS
2ea Batteries
1ea EMS
1ea ARINC
1ea GPS

a 10A breaker is more than enough or is it too big?

 

[thibault]

Galin,

Remember, a C/B is there to protect the wire not the device.

The two power wires to each screen are 22 ga.  So, according to AC 43.13-1B, they can carry between 3 and 6 amps ea in a bundle of wires, depending on the temp rating of the wire.

A 5 amp breaker for each screen should be good, 71/2 OK and 10 is too big because it takes quite an overload to trip a breaker when it is not a direct short.  During that "quite an overload" the wire is getting hotter and hotter.  We need to be sure that the breaker trips long before the wire bursts into flames.

 

[swatson999]

So for:

2ea  D7
2ea ADAHRS
2ea Batteries
1ea EMS
1ea ARINC
1ea GPS

a 10A breaker is more than enough or is it too big?

You might want to put each SV D700 on a separate breaker. If both on one, then you lose both if the CB trips.

 

[ggerhardt]

Ok, I'll check it when I get back home. My breakers aren't that old, but they're pretty easy to swap out. Might be easiest to see what current the breaker trips at.

Now, I just need to figure out how to get home. In Nova Scotia now, hoping for a breaking n the weather on Monday to zip home to MA.

Thanks.

Geoff

 

[GalinHdz]

Galin,

Remember, a C/B is there to protect the wire not the device.

The two power wires to each screen are 22 ga.  So, according to AC 43.13-1B, they can carry between 3 and 6 amps ea in a bundle of wires, depending on the temp rating of the wire.

A 5 amp breaker for each screen should be good, 71/2 OK and 10 is too big because it takes quite an overload to trip a breaker when it is not a direct short.  During that "quite an overload" the wire is getting hotter and hotter.  We need to be sure that the breaker trips long before the wire bursts into flames.

I used 18ga for Power/Gnd since I had lots of it available and I have both displays on the same circuit.

You might want to put each SV D700 on a separate breaker.  If  both on one, then you lose both if the CB trips.

I have a D6 with battery backup and an AERA on a separate breaker, multiple redundant system. Maybe one D700 with the D6 on one breaker, one D700 with the AERA on the separate breaker would be better.

 

[swatson999]

You might want to put each SV D700 on a separate breaker.  If  both on one, then you lose both if the CB trips.

I have a D6 with battery backup and an AERA on a separate breaker, multiple redundant system. Maybe one D700 with the D6 on one breaker, one D700 with the AERA on the separate breaker would be better.

I'd put the D6 on a separate CB from either SV systems, and put backup batteries on both (I only hae one SV and one D6, both with b/u batteries, and they're on separate circuits...in fact, one is on the E-buss and one on the main buss...).  But I can't speak to multiple SVs (with multiple ADAHRS, etc.), as that's not the system I have. 

Just a recommendation to think through what the effects of failure of any piece of the system would be (i.e., a FMECA).

 

[dynonsupport]

We really don't want larger than a 5A breaker on any one given SkyView. You can't put a 18G wire into a DSUB pin, and the pins are only rated at 5A themselves. While a breaker is there to protect the wire, that counts for all things along the current carrying path.

Technically, two D700's have a good chance of operating through a 5A breaker if they don't have backup batteries.