Tough cable

[ptonsparky]

I am needing to run some control in a dairy. Seven runs of 700'+.

I have some left over DB phone cable with a copper shield that sure looks like it would work' Tough jacket and shielded. I can make the control low voltage DC, or whatever I want.

Is there a similar cable that might be more suitable for my installation that would be above 20', not buried.

The thought of running just short a mile of conduit at that height, amongst 3000 head of cows, gives me the shudders.

 

[Tony S]

What sort of control?

If it?s relay then ELV DC will run in to volt drop problems over that distance.

 

[bward]

Yes, voltage drop will make this one tough.

I would recommend an RS-485 or RS-422 based control protocol (take your pick, there are many out there).
Then use a cable like this:
http://www.belden.com/docs/upload/PB244-Databus-Cables-for-FOUNDATION-fieldbus.pdf

Twisted pair, and shielded. Who knows what kind of interference you'll get on a run that long.

You can also get it in an armored jacket if you feel it's necessary.

You'll also need to provide power at each end for the transmitting/receiving device.

FYI, Ethernet can't go that long a distance.

 

[ptonsparky]

I could use a SSR. The one I happen to be looking at uses 4-32VDC control. I need to initiate a Start to another vendors 120VAC equipment.

 

[ptonsparky]

We have used the SSR out to 1000' +-, with the telephone cable we have.

 

[Tony S]

SSR would be the way to go.



That didn?t come across at all well.

 

[gar]

150520-0850 EDT

I can communicate 4000 ft at 115 kbaud (basically 100 kHz) over CAT-5 cable, 8000 ft at 9600 baud.

For your application I suggest looking into a radio frequency link. No wire and installation cost, nor storm damage problems.

If using copper wire and assume 20 mA, then from a 24 V source the maximum wire loop resistance would be about 1200 ohms. Thus, smallest wire size for a 10,000 ft loop is about #30. Any wire that is mechanically rugged is going to work for the application. An optical coupler (the mentioned SSR) will operate on less than 20 mA at a voltage drop of less that 3 V. The coupler itself is only about 1 V drop. Most SSRs have added internal resistance to allow for operation from a voltage source.

.

 

[Cow]

This may be overkill, but what about pvc coated MC cable. I have a job that's about to start on a large dairy and settled on pvc coated mc cable for my circuits. I've never used it but it seems to fit the bill, so I'm giving it a shot.

Another idea, what about radio transmitters/receivers? I've had one of these installed for several years on a water tank float system to start and stop a submersible pump that's a 1/2 mile away with almost zero problems.

http://www.isaacstech.com/radio_products/Series600.htm

The only downside is changing the battery every few years if you don't have a power source available instead. The couple times I've called Isaac's I've gotten great customer service as well.

 

[ptonsparky]

One of my first thoughts was radio...until I realized I still need power for the transmitter.

Three to five years battery life could work if the owners remember to change them and not beat the stuffings out of the PB first.

 

[Cow]

Can you piggyback a power supply off your vendors 120v equipment? The receivers require 12vdc and have contacts in them for switching a load, the transmitters take a battery and only require a 2 wire input to signal the receiver contacts to change state. Thinking about that now, I'm not sure how well that'd work with this controller if you were trying to use a pushbutton, since it's not a maintained contact like an E-stop.

 

[ptonsparky]

Can you piggyback a power supply off your vendors 120v equipment? The receivers require 12vdc and have contacts in them for switching a load, the transmitters take a battery and only require a 2 wire input to signal the receiver contacts to change state. Thinking about that now, I'm not sure how well that'd work with this controller if you were trying to use a pushbutton, since it's not a maintained contact like an E-stop.

I called your guys today. They were certainly interested and are working on a couple different options for me.

Found some gopher proof 2 wire cable as well. . $$

 

[ptonsparky]

This may be overkill, but what about pvc coated MC cable. I have a job that's about to start on a large dairy and settled on pvc coated mc cable for my circuits. I've never used it but it seems to fit the bill, so I'm giving it a shot.

Another idea, what about radio transmitters/receivers? I've had one of these installed for several years on a water tank float system to start and stop a submersible pump that's a 1/2 mile away with almost zero problems.

http://www.isaacstech.com/radio_products/Series600.htm

The only downside is changing the battery every few years if you don't have a power source available instead. The couple times I've called Isaac's I've gotten great customer service as well.

I got a price for the MC cable as well...fittings they quoted were $23.00 each.:jawdrop: I won't stock any of those.

 

[Cow]

I got a price for the MC cable as well...fittings they quoted were $23.00 each.:jawdrop: I won't stock any of those.

That seems high, we are paying a little over half that for these:

https://www.platt.com/platt-electri...Connectors/AFC/595-U/product.aspx?zpid=637031

Our office guy made the same comment though, any extras are going back....

If you're looking for straps as well, this is what I ordered:

http://www.bptfittings.com/Public/Documents/Product/USS ver 2.pdf

 

[JRW 70]

If you can't go microwave tx/rx or other "radio" for
an emergency stop ( if needed ). We have basically
what gar is saying to control our high water pumps
which are a little over a mile away from one of our
plants. They pass under railroad tracks, under a creek,
along the side of a lagoon and have given us nearly
thirty years of reliable service. And pass their semi-
annual DAR and PI test (of the cables rating) If am
able to find out the specifications on the cable I will,
but your project will probably be complete by the time
I can find out. (It may be over a month before I'm
back at that plant again)

(This cable has survived all weather conditions that
we have had here in Missouri) So there almost has to be
something made today that would satisfy all your concerns.

I hope an acceptable solution presents itself for you and your
client.

JR