P-tap on Zephyr top stage

[Alan Rencher]

Does anyone know what type of wire is used for power in the Zephyr? That would also have an impact on the total amperage. 22g wire can handle somewhere around 7-10 amps depending on what type. Maybe I should install this on my sled:

[Victor Lazaro]

Does anyone know what type of wire is used for power in the Zephyr? That would also have an impact on the total amperage. 22g wire can handle somewhere around 7-10 amps depending on what type. Maybe I should install this on my sled:

 

Or use this

[Alan Rencher]

I think the ammeter would be less cumbersome...

Edited November 14, 2012 by Alan Rencher

[Eric Fletcher S.O.C.]

Does anyone know what type of wire is used for power in the Zephyr? That would also have an impact on the total amperage. 22g wire can handle somewhere around 7-10 amps depending on what type.

 

Not exactly correct

 

A few things.

 

22 AWG wire is rated at 7 amps in clear air. That means NOT next to another wire, which is something that we all ignore. if we actually paid attention to that it would mean a current capacity of only 4.6 amps and that will power a film camera, well not a 435 but the rest of them. It will NOT safely power a F900, Viper, Genesis or F23 since they are all 9+ amp cameras.

 

20 AWG is rated at 11 amps in clear air or 6.6 amps in a cable pair/bundle. Still Not enough to power a HD camera.

 

Don't forget the voltage drop due to cable length and remember that length is round trip so double the cable length 20 and 22AWG is not suitable for a RED or Alexa by any stretch of the imagination

[Alan Rencher]

I found this document that is very specific on this issue. In confined space, such as chasis mounting, the standard only allows for 5 amps. This is kind of unnerving for me!

 

http://www.ieee802.org/3/af/public/nov00/vaden_1_1100.pdf

 

 

Current carrying capacity of conductor in free air. (Temperature of conductor carrying indicated current)

Ambient temperature = 30° C

Temp of copper.....80° C.....90° C.....105° C

Size (AWG)............Amps.....Amps.....Amps

26..........................4............5............5

24..........................6............7............7

22..........................8............9............10

 

 

Table 10 Recommended Current ratings (continuous duty) for Electronic Equipment and Chassis

wiring.

(abbreviated)

 

Wire Size....Copper Wire

AWG...........Wiring in free air.....Wiring Confined

28...............1.4..........................0.83

26...............2.2..........................1.3

24...............3.5..........................2.1

22...............7.0..........................5.0

[Eric Fletcher S.O.C.]

I found this document that is very specific on this issue. In confined space, such as chasis mounting, the standard only allows for 5 amps. This is kind of unnerving for me!

 

http://www.ieee802.o...aden_1_1100.pdf

 

 

Current carrying capacity of conductor in free air. (Temperature of conductor carrying indicated current)

Ambient temperature = 30° C

Temp of copper.....80° C.....90° C.....105° C

Size (AWG)............Amps.....Amps.....Amps

26..........................4............5............5

24..........................6............7............7

22..........................8............9............10

 

 

Table 10 Recommended Current ratings (continuous duty) for Electronic Equipment and Chassis

wiring.

(abbreviated)

 

Wire Size....Copper Wire

AWG...........Wiring in free air.....Wiring Confined

28...............1.4..........................0.83

26...............2.2..........................1.3

24...............3.5..........................2.1

22...............7.0..........................5.0

 

Your first table is backwards as temps go up current carrying goes down (Resistance is going up which raises the temp which increases the resistance etc etc it's called a cascade failure)

 

your table 10 has been rounded up. you should always give yourself at least a 20% safety margin so 4.6 amps becomes 3.68 amps.....

 

THis has been posted about often through the years.

[Alan Rencher]

I was just quoting the standards from the IEEE802 website (it's in the PDF that I attached.) "Based on USA Standards Institute, USA Standard C1, Prepared by the National Fire Protection Association, NFPA No. 70."

[Noel Sterrett]

Don't forget the voltage drop due to cable length and remember that length is round trip so double the cable length 20 and 22AWG is not suitable for a RED or Alexa by any stretch of the imagination

 

The Alexa with viewfinder takes around 85W. At 24V that's around 3.5A (actuall less at 28.8 = 2 x 14.4). Shouldn't be a problem for the camera alone.

 

Cheers.

[Eric Fletcher S.O.C.]

Don't forget the voltage drop due to cable length and remember that length is round trip so double the cable length 20 and 22AWG is not suitable for a RED or Alexa by any stretch of the imagination

 

The Alexa with viewfinder takes around 85W. At 24V that's around 3.5A (actuall less at 28.8 = 2 x 14.4). Shouldn't be a problem for the camera alone.

 

Cheers.

 

Now add a follow focus and everything that you need to fly withan Alexa, you are over the power budget

[Eric Fletcher S.O.C.]

Don't forget the voltage drop due to cable length and remember that length is round trip so double the cable length 20 and 22AWG is not suitable for a RED or Alexa by any stretch of the imagination

 

The Alexa with viewfinder takes around 85W. At 24V that's around 3.5A (actuall less at 28.8 = 2 x 14.4). Shouldn't be a problem for the camera alone.

 

Cheers.

 

Now add a follow focus and everything that you need to fly withan Alexa, you are over the power budget

[Noel Sterrett]

Now add a follow focus and everything that you need to fly withan Alexa, you are over the power budget

 

As the charts above show, additional current results in higher heat. But the charts are for continuous current. A Bartech receiver, for example, takes up to 3A, but only when the motor is engaged. Otherwise, it takes only .05A.

 

In addition, the Zephyr sled has two power paths, effectively doubling its current capacity.

 

The Zephyr may be a stretch for an Alexa, but with careful setup, it seems quite doable.

 

Not so sure about an F65...

 

Cheers.

[Eric Fletcher S.O.C.]

In addition, the Zephyr sled has two power paths, effectively doubling its current capacity.

 

Where? It appears to share a common ground making it a single power path

[Noel Sterrett]

Where? It appears to share a common ground making it a single power path

 

There are four wires passing through the post (Red, White, Black, Orange). I'm not sure how they are currently wired, but that could be easily changed.

 

In any event, the Alexa draws 85W while recording to SxS. So like follow focus, it's not a continuous power draw. And as I pointed out, the wire capacities are calculated for continuous, not intermittent current.

 

I've done the math, and I'm comfortable I could rig and fly an Alexa on a Zephyr with necessary accessories.

 

I'm actually more concerned with my back holding up than the wiring.

 

Cheers.

[Victor Lazaro]

I would be more worried about the maximum weight on the arm (23 lb of camera weight)

Alexa ~ 15 lb

Lens ~ 4 lb

Wireless video ~ 1 lb

Wireless ff ~ 2.5 lb

wires ~ .5lb

matte box ~ 1 lb

=25 lb

That's without the codex (5.7 lb)

[Calculated form average weights found online]

 

The Epic's body being 5lb, it's still within the range, and even a bit of room for a battery (AB Dionic HC is 1.8 lb plus the battery plate) on it's back (solving the whole wiring issue)...

 

This is one of the reasons why I am looking into a larger rig soon.

[Noel Sterrett]

I would be more worried about the maximum weight on the arm (23 lb of camera weight)

Alexa ~ 15 lb

Lens ~ 4 lb

Wireless video ~ 1 lb

Wireless ff ~ 2.5 lb

wires ~ .5lb

matte box ~ 1 lb

=25 lb

That's without the codex (5.7 lb)

[Calculated form average weights found online]

 

The Epic's body being 5lb, it's still within the range, and even a bit of room for a battery (AB Dionic HC is 1.8 lb plus the battery plate) on it's back (solving the whole wiring issue)...

 

This is one of the reasons why I am looking into a larger rig soon.

 

The Alexa is 13.8 lb

The Alexa Plus is 15 lb, but has built in wireless video

There are many great lenses less than 4 lb

 

I'm not saying it's ideal, but just that it can be done with careful wiring and selection of accessories.

 

On the other hand, the Sony F5/55 ( 4.4 lb, 25W ) should be a cakewalk.

 

Cheers.