Automatic gate and voltage drop

[Shaneyj]

Scenario: 670' from power source. Automatically gate opener and a couple lights.
Gate opener not picked out yet.
For those of you familiar with different auto gate options, is there a ball park of ranges for power demand to determine what size circuit is needed?
Any thoughts on increasing conductors vs using buck/boost transformer to account for voltage drop?


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[GoldDigger]

Scenario: 670' from power source. Automatically gate opener and a couple lights.
Gate opener not picked out yet.
For those of you familiar with different auto gate options, is there a ball park of ranges for power demand to determine what size circuit is needed?
Any thoughts on increasing conductors vs using buck/boost transformer to account for voltage drop?


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Most automatic gate openers that I am familiar with (residential size only) are DC actuated and use a local battery and charger instead of running an AC motor directly. This greatly reduces the significance of voltage drop on the long feed wires, and allows the gate to open and close several times after power is lost.

 

[iwire]

Forget buck boosts for voltage drop.

I can't answer the circuit size but I would press the customer to specify a 240 volt unit to reduce the current.

 

[Shaneyj]

Forget buck boosts for voltage drop.


Can you elaborate on the logic here? For my education.

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[iwire]

Can you elaborate on the logic here? For my education.

You have a load that stops and starts, voltage drop is current dependent.

You would end up with a very high open circuit voltage if you boost it enough to be correct during start up and running.

 

[ActionDave]

Check on the gate opener like Goldy said, lots of times all you need is enough juice for the lights and a battery charger. I just finished one that was about 1500 feet, ran the whole thing in 10AWG.

If it is a motor driven opener you would want it 240V and it would most likely be a 20A circuit.

 

[GoldDigger]

You have a load that stops and starts, voltage drop is current dependent.

You would end up with a very high open circuit voltage if you boost it enough to be correct during start up and running.

But if the gate control and motor are the only thing on that branch circuit (no general use or decoration receptacle as part of the gate structure) then the high open circuit voltage may not be a problem.
As a general rule for intermittent loads on a shared circuit a boost transformer is not ideal.

 

[ActionDave]

But if the gate control and motor are the only thing on that branch circuit (no general use or decoration receptacle as part of the gate structure) then the high open circuit voltage may not be a problem.
As a general rule for intermittent loads on a shared circuit a boost transformer is not ideal.

Don't use a buck boost for voltage drop is a good rule of thumb and there is no need for it in this case.

 

[iwire]

But if the gate control and motor are the only thing on that branch circuit (no general use or decoration receptacle as part of the gate structure) then the high open circuit voltage may not be a problem.
As a general rule for intermittent loads on a shared circuit a boost transformer is not ideal.

I don't think the typical control circuit is going to like the overvoltage while waiting to run motor but it might ... Do you like gambling? I don't.

That said it seems if it is a unit like you describe the current draw would be low so running enough wire for it might not be that bad.

 

[GoldDigger]

Don't use a buck boost for voltage drop is a good rule of thumb and there is no need for it in this case.

Perhaps more important than a general rule in this particular case is that the voltage drop caused by motor inrush will be several times greater than the running voltage drop, so boosting out the running voltage drop will not help starting significantly. Lowering the circuit resistance is the right way to go. For really long runs, a step-up/step-down configuration may be practical.

 

[mpoulton]

This sounds like a good application for solar, to me.

 

[ActionDave]

This sounds like a good application for solar, to me.

There is more maintenance with the solar panel and it's not that good if you want a light. Most times you need a phone line so there is already going to be a ditch.

 

[iwire]

Perhaps more important than a general rule in this particular case is that the voltage drop caused by motor inrush will be several times greater than the running voltage drop, so boosting out the running voltage drop will not help starting significantly.

Sounds familiar

if you boost it enough to be correct during start up and running.

 

[GoldDigger]

Sounds familiar

There is no way to boost it to be nominal for both stating and running unless you put in a voltage regulator.
What is the cost of a Sola constant voltage transformer (CVT) these days? Might actually be viable option.
The big downside of that (besides initial cost) is that the magnetizing current in the transformer will be burning up power in IR loss 24/7 and the transformer itself gets pretty hot. (I have one sitting in storage at the moment that I got at an auction for $10 many years ago.)

 

[ActionDave]

There is no way to boost it to be nominal for both stating and running unless you put in a voltage regulator.
What is the cost of a Sola constant voltage transformer (CVT) these days? Might actually be viable option.
The big downside of that (besides initial cost) is that the magnetizing current in the transformer will be burning up power in IR loss 24/7 and the transformer itself gets pretty hot. (I have one sitting in storage at the moment that I got at an auction for $10 many years ago.)

The big downside is there is no upside to using a boost transformer in this application no matter how you accereize it. A prom dress isn't gonna look good on a pig, it just isnt.

 

[Ingenieur]

Most automatic gate openers that I am familiar with (residential size only) are DC actuated and use a local battery and charger instead of running an AC motor directly. This greatly reduces the significance of voltage drop on the long feed wires, and allows the gate to open and close several times after power is lost.

that is the way to go
great idea

figure 2 A #14 only 6% drop
1 A when charging at ~10 A dc, then trickle down
1 A for the light

data sheet for one, various methods, up to 1000' #12 or #10
http://www.allgateoperatormanuals.com/RSL 12V Manual.pdf