Transfer 24 VDC to 1000 ft...

Thread Starter

maitrey

Joined Sep 4, 2014
57
Hello,

I have to transfer 24 VDC to 21 devices which is 1000 ft apart. Is it possible to transfer 24 VDC to such a long distance?

This 24 VDC is coming from SMPS. Does the current/power rating matter in this case?

And how can I calculate total voltage drop at the end (If there is any)?. All 21 devices will be activated at the same time through single 24 VDC source.

Please share your thoughts.

Thanks in advance,
 

Papabravo

Joined Feb 24, 2006
13,741
Hello,

I have to transfer 24 VDC to 21 devices which is 1000 ft apart. Is it possible to transfer 24 VDC to such a long distance?

This 24 VDC is coming from SMPS. Does the current/power rating matter in this case?

And how can I calculate total voltage drop at the end (If there is any)?. All 21 devices will be activated at the same time through single 24 VDC source.

Please share your thoughts.

Thanks in advance,
It is possible, but there are some things to consider:
  1. You won't get the full 24 volts @ 1000' away from the supply. You might only get +11 VDC
  2. Wire gage
  3. The IR loss from the supply to the farthest node along the power wire
  4. The identical IR loss along the ground return
  5. The total current that needs to be drawn by the attached devices
  6. The signaling methods used by the devices
  7. Common mode voltage problems
  8. Flexibility in choosing the location for the supply.
  9. Regulatory requirements, like NEC, or CE Mark
We considered all of this stuff and much more when designing the physical layer for DeviceNet.
 
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Thread Starter

maitrey

Joined Sep 4, 2014
57
The device is basically a valve actuator (ON/OFF) which only has an option to connect either 8-pin M12 connector cable on (X3) or 7 pin plug binder type 693 connector cable on (X1). I can use either of these two for this whole application.

However, the power supply for this actuator will also be coming from same connector. So, I don't really have a choice other than to use M12 or 693 connector. So, total two 24 VDC and both comes from different power source.

1. Power supply (continuous)
2. 24 VDC to trigger on/off

Below is the load data.
I interpret this as to provide greater than 14 V DC to OPEN and less than 8 VDC to close. Not sure If I am correct.

1586545248527.png

Does this makes sense?

Thanks,
 

Papabravo

Joined Feb 24, 2006
13,741
No, not really. I'm not familiar with either of those connector types. What I would like to see is a schematic drawing showing the power source, and the signal source. On each device I count a total of 15 pins. How are the other pins used and how do you wire all the devices onto an n(?)-conductor cable. What wire gauge would be used in the cable?
 

Thread Starter

maitrey

Joined Sep 4, 2014
57
I know there are so many other questions. Even, I am having hard time reading data sheet of this actuator to figure out electrical connections I have to make. But, it looks like connector X1 is used for 24 VDC power supply and X3 is for digital inputs (on/off) signal.

Cable assemblies:
1. X1: 7-pin binder type 693
2. X3: 8-pin, M12, (https://www.phoenixcontact.com/online/portal/us?uri=pxc-oc-itemdetail:pid=1513758&library=usen&tab=1&requestType=product&productId=1513758&productDetection=true&redirectTarget=country&redirectTo=US)

Please see attahced. Hope this makes sense.

P.S. 1000 ft is the worst case assumption.
 

Attachments

MaxHeadRoom

Joined Jul 18, 2013
20,707
You need one of the specialty power supplies with voltage sense, it means another small gauge pair for the sense lines, but this corrects the P.S. output voltage in order that the supply at the load remains constant.
Particularly important if the load varies.
Max.
 

Thread Starter

maitrey

Joined Sep 4, 2014
57
You need one of the specialty power supplies with voltage sense, it means another small gauge pair for the sense lines, but this corrects the P.S. output voltage in order that the supply at the load remains constant.
Particularly important if the load varies.
Max.
I just hope that I am not oversizing anything in this case.

The SMPS which i chose is 24 VDC/5A/120 Watts. Should I go for larger current/power ratings like 200 watts? Since this is the only SMPS providing 24 VDC to 21 devices. All at the same time.
 
If the image is correct, that each unit requires 5 amps and you'll wire 21 of them.... 105 amps at 24 volts for 1000 ft?

The copper wire costs will be prohibitively expensive.
 

Thread Starter

maitrey

Joined Sep 4, 2014
57
If the image is correct, that each unit requires 5 amps and you'll wire 21 of them.... 105 amps at 24 volts for 1000 ft?

The copper wire costs will be prohibitively expensive.
5A is the total capacity of SMPS (Power supply). I have 21 devices in total. I am not sure if 2.5 mA is the current requirement for each devices?? Please see attached,,
 

Attachments

crutschow

Joined Mar 14, 2008
24,980
You need one of the specialty power supplies with voltage sense, it means another small gauge pair for the sense lines, but this corrects the P.S. output voltage in order that the supply at the load remains constant.
Particularly important if the load varies.
That's a good approach.
If you don't want to run another two wires, you can add a circuit at the power supply that detects the current and adjusts the power supply voltage to adjust for the known wire resistance voltage drop.
An opamp that senses the current in the return line should be able to do that.
 

Thread Starter

maitrey

Joined Sep 4, 2014
57
That's a good approach.
If you don't want to run another two wires, you can add a circuit at the power supply that detects the current and adjusts the power supply voltage to adjust for the known wire resistance voltage drop.
An opamp that senses the current in the return line should be able to do that.
Don't want to add any additional circuit here. Any part# for built-in voltage sense smps?
 

MaxHeadRoom

Joined Jul 18, 2013
20,707
One of the few makes I used was GFC Power, I believe they are owned by Hammond now, there are a few others similar design.
They were basically linear supplies, some also had crowbar overload shut down.
Max.
 

Papabravo

Joined Feb 24, 2006
13,741
You have no chance to supply 21 devices at 24V and 5 amperes each with a single pair of #12 AWG. It is not clear that you would be able to daisy chain the connections in any case. That means a long run for each device or 42,000 feet of wire. You must be mad if that is your plan. For the on/off control are they all going to be controlled by a single signal or are we going to need another 42,000 feet of wire for the 21 signals and their ground returns?

Show me a drawing of the cable from the power supply to each of the 21 devices, and how you will fabricate the cable.
 
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Thread Starter

maitrey

Joined Sep 4, 2014
57
You have no chance to supply 21 devices at 24V and 5 amperes each with a single pair of #12 AWG. It is not clear that you would be able to daisy chain the connections in any case. That means a long run for each device or 42,000 feet of wire. You must be mad if that is your plan. For the on/off control are they all going to be controlled by a single signal or are we going to need another 42,000 feet of wire for the 21 signals and their ground returns?
You misunderstood the whole concept!

5A is the max capacity of SMPS meaning I have total 5A of current which will be distributed between 21 devices. Now from the data sheet I assume that each device requires 2.5mA of current at 24 VDC and if all devices are to be ON at the same time means 2.5 mA x 21 = ______ . Isn't it right?

Not sure where #12 AWG came from. I am using 7-pin circular cable for power supply (Don't know gauge of each wire)
 

Alec_t

Joined Sep 17, 2013
11,302
How often will the actuators be energised, and for how long? Would it be possible to provide each actuator with a super-capacitor or small rehargeable battery as a local power supply kept trickle-charged by the main supply?
 

Papabravo

Joined Feb 24, 2006
13,741
You misunderstood the whole concept!

5A is the max capacity of SMPS meaning I have total 5A of current which will be distributed between 21 devices. Now from the data sheet I assume that each device requires 2.5mA of current at 24 VDC and if all devices are to be ON at the same time means 2.5 mA x 21 = ______ . Isn't it right?
No wrong. Each device requires 5A from the power supply. The input stage of the circuitry for the on/off signal requires a low amount of current which was not specified on the picture you showed us.

You still can't push 5A through 1000' feet of wire without significant voltage loss
I don't think these devices are meant to be daisy chained.
You should get a device and test it!
 

Thread Starter

maitrey

Joined Sep 4, 2014
57
No wrong. Each device requires 5A from the power supply. The input stage of the circuitry for the on/off signal requires a low amount of current which was not specified on the picture you showed us.

You should get a device and test it!
Correct. My bad. Thanks for clearing this!

The device requiers 24 VDC power supply and its total power consumption is 65 Watts max. (This is too much for an actuator!)
Does it mean that each device requiers 24 VDC/ 2.70 A? And If I have 5A coming from SMPS then it won't be sufficient??
 
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