48VDC Positive ground and the WS DC line
- RSENG-Eric
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Re: 48VDC Positive ground and the WS DC line
Did this ever go anywhere? We have need for 17 sites with -48VDC that I want to avoid buying inverters for.
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sirhc - Employee
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Re: 48VDC Positive ground and the WS DC line
Not sure what you mean by go anywhere? If your asking if the units have changed then no, they are still not isolated power supplies?
We have thought about building one but it would add $50 to $100 to the MSRP since our WS-12-250-DC unit works all the way down to 9V the amperage gets pretty high and makes building an isolated circuit into the board expensive.
It would have to be a special unit that only accept -48V +/- and then the question is how many could we sell to justify the RND and NRE costs and how large of production batches could be build?
We have not discarded the concept but we have not acted on it yet either.
The switches currently are not designed with isolated power supplies so simply swapping the input leads to the switch does not work most times as most radios out there have their DC negative connected to the tower or Earth Ground and the tower grounding system should always be connected/bonded to the equipment racks and service ground so if the -48V DC power has the wrong polarity (after you swap them) bonded to the rail and or Earth ground then when you plug in any radios or connect the switch chassis ground lug to the rail and or Earth ground you will get white smoke.
We have thought about building one but it would add $50 to $100 to the MSRP since our WS-12-250-DC unit works all the way down to 9V the amperage gets pretty high and makes building an isolated circuit into the board expensive.
It would have to be a special unit that only accept -48V +/- and then the question is how many could we sell to justify the RND and NRE costs and how large of production batches could be build?
We have not discarded the concept but we have not acted on it yet either.
The switches currently are not designed with isolated power supplies so simply swapping the input leads to the switch does not work most times as most radios out there have their DC negative connected to the tower or Earth Ground and the tower grounding system should always be connected/bonded to the equipment racks and service ground so if the -48V DC power has the wrong polarity (after you swap them) bonded to the rail and or Earth ground then when you plug in any radios or connect the switch chassis ground lug to the rail and or Earth ground you will get white smoke.
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lligetfa - Associate
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Re: 48VDC Positive ground and the WS DC line
RSENG-Eric wrote:Did this ever go anywhere? We have need for 17 sites with -48VDC that I want to avoid buying inverters for.
I'm going to assume the -48V is regulated so all that is needed is a polarity inverter to use with the WS-12-DC that doesn't have a Smart DC power supply.
How much do polarity inverters go for? I wonder if the $100 lower price on the WS-12-DC would offset it?
- RSENG-Eric
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Re: 48VDC Positive ground and the WS DC line
In the past, we've used the Mean Well SD-200C-48 / SD-500L-48 for isolating 48VDC, but at a cost of $80/$130, I'd much rather have it built into the switch.
I also disagree with the notion that adding an isolated supply would negate the wide input option.
If it's not something that Netonix has a desire to do, I will stop waiting, and I'll engineer the site around it. Licensed microwave and carrier ethernet switches are all -48VDC, except UB (But who wants to use coax on 11GHz?!).
Wispswitch is a fabulous product. Keep up the good work!
I also disagree with the notion that adding an isolated supply would negate the wide input option.
If it's not something that Netonix has a desire to do, I will stop waiting, and I'll engineer the site around it. Licensed microwave and carrier ethernet switches are all -48VDC, except UB (But who wants to use coax on 11GHz?!).
Wispswitch is a fabulous product. Keep up the good work!
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highlands - Member
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Re: 48VDC Positive ground and the WS DC line
I too have had to engineer around this issues at 6 sites so far and have not at 8 others have -48VDC that I do not have the Netonix solution at because of this issue.
Netonix does make a great product is a fact!
I do wish they would separate the product in to two product lines, AC and DC. It appears that they take a AC product and adapt it to a DC environment. When in a 48 VDC (or positive or negative ground) environment we already have clean DC power and do not have a need the wide front in of the most of the DC product line have. What our desire would be is a DC front end that accepts 40 to 70 for these two reasons.
(1) The LVD (low voltage disconnect) kicks in (or should I say out) at about 46VDC (+- 3VDC), there for any voltage below that is unneeded as the power is removed.
(2) The float voltage of a 48 String is (depending on the chemical battery type) typically 52 to 56VDC and the equalize voltage of those same batteries are 56 to 60VDC. In my opinion the 37V to 53V 'window is too small and almost designed to push you to the more expensive and consumes more power (solar sites this can be an issue) of the DC line has the DC to DC power supply built in. When looking at almost any telecom gear they have those front end power supplies that handle on average 40 to 72VDC. There will be push back from those WISPs running 12 and 24VDC solar site (like we used to) as they will state the need for lower voltages, and I agree, which means the DC line even need to be broken up into two groups.
(1) the SMART DC power supply accepts 9V to 60V DC. This is a near perfect product and works very well!
(2) A NOT SMART DC power supply, but yet accepts 40V to at lest 60VDC and 72VDC or so would be better. then add some configurable jumpers inside that could be changed so as to make it positive or negative ground possible. Although the opening on the unit may void the warranty so as an alternative have the unit with two sets of power inputs and isolate the frame and CAT5 shielding from the power altogether making it a frame ground. Many manufactures do just that so that their product can go either way. However remember those product REQUIRE all 3 connections, 2 power and a frame ground!! Do not run it on power only, if you do you can kiss some of you gear goodbye on the first storm that rolls through!
Well there is my nickel's worth. Please Please do not take this post as a negative, it is a suggestion for what would be nice to have.
John
Netonix does make a great product is a fact!
I do wish they would separate the product in to two product lines, AC and DC. It appears that they take a AC product and adapt it to a DC environment. When in a 48 VDC (or positive or negative ground) environment we already have clean DC power and do not have a need the wide front in of the most of the DC product line have. What our desire would be is a DC front end that accepts 40 to 70 for these two reasons.
(1) The LVD (low voltage disconnect) kicks in (or should I say out) at about 46VDC (+- 3VDC), there for any voltage below that is unneeded as the power is removed.
(2) The float voltage of a 48 String is (depending on the chemical battery type) typically 52 to 56VDC and the equalize voltage of those same batteries are 56 to 60VDC. In my opinion the 37V to 53V 'window is too small and almost designed to push you to the more expensive and consumes more power (solar sites this can be an issue) of the DC line has the DC to DC power supply built in. When looking at almost any telecom gear they have those front end power supplies that handle on average 40 to 72VDC. There will be push back from those WISPs running 12 and 24VDC solar site (like we used to) as they will state the need for lower voltages, and I agree, which means the DC line even need to be broken up into two groups.
(1) the SMART DC power supply accepts 9V to 60V DC. This is a near perfect product and works very well!
(2) A NOT SMART DC power supply, but yet accepts 40V to at lest 60VDC and 72VDC or so would be better. then add some configurable jumpers inside that could be changed so as to make it positive or negative ground possible. Although the opening on the unit may void the warranty so as an alternative have the unit with two sets of power inputs and isolate the frame and CAT5 shielding from the power altogether making it a frame ground. Many manufactures do just that so that their product can go either way. However remember those product REQUIRE all 3 connections, 2 power and a frame ground!! Do not run it on power only, if you do you can kiss some of you gear goodbye on the first storm that rolls through!
Well there is my nickel's worth. Please Please do not take this post as a negative, it is a suggestion for what would be nice to have.
John
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Dave - Employee
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Re: 48VDC Positive ground and the WS DC line
thanks for your comments...unlike some of the other vendors....we do listen to customer feedback & apply positive suggestions to future products... 
Re: 48VDC Positive ground and the WS DC line
If I put an SD-500L-48 on a positive ground 48V system I can then safely plug in any of the Netonix switches that accept 48V within its range into the other side of the SD-500L-48? (I received a hand-me-down -48V power system and I don't know that much about -48V)
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sirhc - Employee
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Re: 48VDC Positive ground and the WS DC line
So our switches are really not meant to work on -48V sites but some people use an ISOLATED DC power supply to feed a WS-12-DC .
If your power supply is ISOLATED and you bond their ground rail to our Chassis ground lug you "SHOULD" be OK? Make sure what ever you connect to our lug is the same ground as the tower itself.
Since you are using a power supply and not hooking the switch direct to batteries you do not want the SMART DC unit [WS-12-250-DC) as that would be a waste of money.
You could also use the new WS-26-DC.
However be careful and use your meter to test as much as possible.
We also have the new WS-26-400-IDC which has its own ISOLATED power supply which you use but we are out of stock for several more weeks but this too should be used with caution.
If your power supply is ISOLATED and you bond their ground rail to our Chassis ground lug you "SHOULD" be OK? Make sure what ever you connect to our lug is the same ground as the tower itself.
Since you are using a power supply and not hooking the switch direct to batteries you do not want the SMART DC unit [WS-12-250-DC) as that would be a waste of money.
You could also use the new WS-26-DC.
However be careful and use your meter to test as much as possible.
We also have the new WS-26-400-IDC which has its own ISOLATED power supply which you use but we are out of stock for several more weeks but this too should be used with caution.
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calebp - Member
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Re: 48VDC Positive ground and the WS DC line
Hey everyone,
Could someone post how to connect the output on the Meanwell SD-500L-48 to the Netonix to avoid damaging the Netonix WS-12-250-DC? The Meanwell documentation shows a +Vo +Vo -Vo -Vo for output, but it says it only supports one output.
Could someone post how to connect the output on the Meanwell SD-500L-48 to the Netonix to avoid damaging the Netonix WS-12-250-DC? The Meanwell documentation shows a +Vo +Vo -Vo -Vo for output, but it says it only supports one output.
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sirhc - Employee
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Re: 48VDC Positive ground and the WS DC line
calebp wrote:Hey everyone,
Could someone post how to connect the output on the Meanwell SD-500L-48 to the Netonix to avoid damaging the Netonix WS-12-250-DC? The Meanwell documentation shows a +Vo +Vo -Vo -Vo for output, but it says it only supports one output.
Why would you use a WS-12-250-DC which is designed to hook "directly" to a battery bank not a power supply.
You should be using the WS-12-DC which is designed to hook to a power supply and is considerably cheaper.
The Meanwell Spec Sheet provides all you need to know: https://www.trcelectronics.com/ecomm/pdf/sd500.pdf
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