hello all brand new at the site,have a job to bid ,i have six cameras to provide120vac power , underground in pvc each draw 4amps furthest 2 are 1225feet away then 950ft. then 675ft. Iam figuring 2 20 amp circuits or can i put them on a larger breaker and run 1 set of feeds to them, also for the voltage drop can i run my largest wire to the first drop. then down size my wire as the amp draw drops. thanks for any help.
voltage drop question
- Thread starter chris11
- Start date
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gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090402-0717 EST
Why does a camera need 500 W?
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Why does a camera need 500 W?
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charlie
Senior Member
- Location
- Indianapolis
You can do it either way as long as the voltage drop is reasonable. :smile:
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
Transformers young man transformers.
utilizing 120 VAC to 480 VAC and then back to 120 VAC
Solution:
1 conductor(s) per phase utilizing a 3 kcmil Copper conductor will limit the voltage drop to 2.87% or less when supplying 24 amps for 1224 feet on a 480 volt system.
utilizing 120 VAC to 600 VAC and then back to 120 VAC
Solution:
1 conductor(s) per phase utilizing a 4 kcmil Copper conductor will limit the voltage drop to 2.81% or less when supplying 24 amps for 1224 feet on a 600 volt system.
utilizing 120 VAC to 480 VAC and then back to 120 VAC
Solution:
1 conductor(s) per phase utilizing a 3 kcmil Copper conductor will limit the voltage drop to 2.87% or less when supplying 24 amps for 1224 feet on a 480 volt system.
utilizing 120 VAC to 600 VAC and then back to 120 VAC
Solution:
1 conductor(s) per phase utilizing a 4 kcmil Copper conductor will limit the voltage drop to 2.81% or less when supplying 24 amps for 1224 feet on a 600 volt system.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090402-0755 EST
Can the heaters be separated from the camera power?
What are the camera specifications for input voltage?
Are the heaters bang-bang servos or proportional? At what temperature are the heaters on continuously? What is the lowest temperature at the installed location? What happens to the camera system if voltage drops to 95V, 80V, and 60V?
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Can the heaters be separated from the camera power?
What are the camera specifications for input voltage?
Are the heaters bang-bang servos or proportional? At what temperature are the heaters on continuously? What is the lowest temperature at the installed location? What happens to the camera system if voltage drops to 95V, 80V, and 60V?
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ronmath
Senior Member
- Location
- Burnsville, MN
This does seem the best way to do this, however instead of taking the full 24 amps at 1224 feet as suggested, you only have 24 amps for 675 feet then 16 amps for 275 more feet and 8 amps for the final 275 feet. This would allow you to run #4 wire at 480 volt instead of #3 as suggested. IMHO
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090402-0830 EST
chris11:
I believe you are saying that the heater power can be separated from the camera power. Is that correct?
You need quantitative data on on the voltage range, min and max, over which the camera can operate. Also can the camera operate on DC? I have one camera that requires AC for the base 60 Hz timing information. Others I have do not require AC and will work on AC or DC. These have their own internal frequency generator.
If the cameras can work on DC, then you could easily provide a local DC regulator and operate with a large AC voltage variation.
I suspect that in NJ you will virtually never get below -10 deg. F.
To what minimum outside temperature will the camera heater provide the internal 40 deg. F. when the heater is on continuously?
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chris11:
I believe you are saying that the heater power can be separated from the camera power. Is that correct?
You need quantitative data on on the voltage range, min and max, over which the camera can operate. Also can the camera operate on DC? I have one camera that requires AC for the base 60 Hz timing information. Others I have do not require AC and will work on AC or DC. These have their own internal frequency generator.
If the cameras can work on DC, then you could easily provide a local DC regulator and operate with a large AC voltage variation.
I suspect that in NJ you will virtually never get below -10 deg. F.
To what minimum outside temperature will the camera heater provide the internal 40 deg. F. when the heater is on continuously?
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Last edited:
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090402-0900 EST
chris11:
I realize the cameras are presently being supplied by AC. The question is can that camera also operate on DC? If the cameras have not already been purchased, then can ones that operate on AC and DC be used instead?
Note: Internally any camera operates from DC. If 60 Hz AC is required, then it is only a requirement because the camera uses this for synchronization of the vertical frequency.
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chris11:
I realize the cameras are presently being supplied by AC. The question is can that camera also operate on DC? If the cameras have not already been purchased, then can ones that operate on AC and DC be used instead?
Note: Internally any camera operates from DC. If 60 Hz AC is required, then it is only a requirement because the camera uses this for synchronization of the vertical frequency.
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the cameras only operate on 24 ac.just talked to the vendor.and i am trying to find out the exact draw per camera for the 120vac feed. they just said 4 amps the most. just recieved call now it is 2 amps. looks like my proposal will have alot of contingencies to cover myself.
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
Heaters don't mind till they don't melt the snow and something expensive is stolen, then you are held liable.
I'll bet the heaters are way oversized for the exact same reasons. That, and I bet the camera manufacturers have often found their cameras at the end of 1000' of #14 wire. (A lot of these are probably installed by security people who have no idea what voltage drop even is.)
Just a guess, but I would really think the camera and heater are designed to handle large voltage drops just in the intrest of keeping a good reputation with the same installers who have no clue about voltage drop.
So I'd call the camera vendor or manufacturer and ask. It might be well worth a phone call.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090402-1244 EST
chris11:
Here is reference to a high performance camera:
http://www.compumodules.com/image-p...shi/high-sensitivity-surveillance-camera.html
and
http://www.compumodules.com/image-processing/hitachi-denshi/pdf/KP_DE500.pdf
Without heater it works to -10 deg. C. which is 32-18 = +14 deg. F.
Its power requirement including lens control is 12V @ 1.5 A max = 18 W. This reflected to 240 V at 70% efficiency is 0.075/0.7 = 0.11 A. There are small switching regulators that work from 88 to 264 V AC to regulated 12 VDC. Also a wide temperature range.
Here is an example:
http://www.cui.com/pdffiles/VGS-25-XX.pdf
For cameras without heaters you would need about 0.7 A at 240 V. You would have no concern about line voltage drop. Suppose each heater was 50 W. This adds 300 W to the total load but could tolerate wide voltage variations. 300 W at 240 V = 1.25 A. Seldom would all heaters be on at once. Even if you had 100 V drop at the end of the line when all the heaters were on it would not matter so long as the design was such that sufficient heat was provided at the lowest required temperature.
Suppose #12 wire was used and the loop length was 2500 ft. The loop resistance is 1.6*2.5 = 4 ohms. At 2 A at the end of this 1250 line the voltage drop is 8 V.
I think you need to look at other options rather than a brute force approach. Or at least your customer does.
You also need to worry about undesired currents on the video cables (ground current flowing on the cable shield).
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chris11:
Here is reference to a high performance camera:
http://www.compumodules.com/image-p...shi/high-sensitivity-surveillance-camera.html
and
http://www.compumodules.com/image-processing/hitachi-denshi/pdf/KP_DE500.pdf
Without heater it works to -10 deg. C. which is 32-18 = +14 deg. F.
Its power requirement including lens control is 12V @ 1.5 A max = 18 W. This reflected to 240 V at 70% efficiency is 0.075/0.7 = 0.11 A. There are small switching regulators that work from 88 to 264 V AC to regulated 12 VDC. Also a wide temperature range.
Here is an example:
http://www.cui.com/pdffiles/VGS-25-XX.pdf
For cameras without heaters you would need about 0.7 A at 240 V. You would have no concern about line voltage drop. Suppose each heater was 50 W. This adds 300 W to the total load but could tolerate wide voltage variations. 300 W at 240 V = 1.25 A. Seldom would all heaters be on at once. Even if you had 100 V drop at the end of the line when all the heaters were on it would not matter so long as the design was such that sufficient heat was provided at the lowest required temperature.
Suppose #12 wire was used and the loop length was 2500 ft. The loop resistance is 1.6*2.5 = 4 ohms. At 2 A at the end of this 1250 line the voltage drop is 8 V.
I think you need to look at other options rather than a brute force approach. Or at least your customer does.
You also need to worry about undesired currents on the video cables (ground current flowing on the cable shield).
.
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