WS-12-250-DC shutting off

[Steffan]

I have managed to power a PTP 800 using all 4 pairs on 48vH in port one, on the specifications it states it should deliver 2a but is only showing 1.5a in the options, this powers the 800 drawing 12w, as soon as we plug in a network cable through the in-band-management port the switch shuts down.

Place a dumb switch in between and its fine, it seems like there is some sort of a short of some sorts once the patch lead is connected.

We have several 800's in our network and could do with powering these over DC.

Any help and support would be gratefully received.

Thanks in advance

Steff

[sirhc]

I am not familiar with that radio. Maybe if you link in a spec sheet or PDF that calls out the POE power polarity PIN out and the watts needed I could assist you.
NOTE: Our switches are rated at 1.5A for 48VH which is really 50V as we called it 48V so people did not get confused as they are used to 48V but our Device/Status TAB clearly says what the voltage is.

As far as 2A we say that it can spike to 2A and in cooler environments it will push 2A but that is the very very upper limit as the Ethernet Transformers are only rated at 1A per pair so 2 pairs (using all 4 pairs) you get 2A

[Steffan]

Hi Sirhc

Thanks for your help so far, you can view the spec of the link here, here's how we have everything set up on our test bench:

Battery Setup:




Netonix setup (this is a test power cable instead of the 4pair but it does the same on both)



Voltages on the switch


With an intermediate switch everything works OK


When we connect the lan port for the data to the netonix directly it shuts down and re-boots.
Here is a picture of the original power supply which works:




Thanks in advance

Steff

[sirhc]

Well first off that power tab is not designed for 48VH as it only uses PINS 4,5 for positive and PINS 7,8 for negative

48VH needs PINs 1,2,4,5 for positive and PINS 3,6,7,8 for negative which spreads the load out over all 8 wires not just 4

It is fine for 48V as it only uses 2 Pair or 4 wires to carry current which is fine for our 48V POE option.

All this is explained in this post as to what each POE option uses as far as PINs and polarity: viewtopic.php?f=6&t=1178#p8809

Question: Can I power this device with Netonix.

Answer: Our switches are "passive" POE which means if POE is enabled on a port the power is live so if you plug in a cable that is shorted or the piece of equipment is bad or has an incompatible polarity PIN OUT you will damage the port in the switch and probably the equipment, this damage is not covered under warranty.

There are 4 Pairs and 8 PINs in an Ethernet Cable:
Pair 1: White Orange.(PIN 1 ) & Orange.(PIN 2) is POSITIVE
Pair 2: White Green...(PIN 3) & Green...(PIN 6) is NEGATIVE
Pair 3: White Blue.....(PIN 4) & Blue.....(PIN 5) is POSITIVE
Pair 4: White Brown..(PIN 7) & Brown...(PIN 8) is NEGATIVE

24V POE Option @ .75A - constant draw can surge/spike to 1A:
802.3af/at MODE B [i]pinout[/i]
Pair 3 / PINs 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE

48V POE Option @.75A - constant draw can surge/spike to 1A:
802.3af/at MODE B [i]pinout[/i]
You would use this option to power most 802.3af/at devices like IP Phones and Cameras
Pair 3 / PINs 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE

24VH POE Option @1.5A - constant draw can surge/spike to 2A:
802.3af/at MODE A & MODE B [i]pinout combined[/i]
Pair 1 & 3 / PINs 1, 2, 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE

48VH POE Option @1.5A - constant draw can surge/spike to 2A:
802.3af/at MODE A & MODE B [i]pinout combined[/i]
Pair 1 & 3 / PINs 1, 2, 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE

So now that you know what the PIN OUT is (which is in our Spec Sheet on page 17 and in the product description on our web store) all you need to do is look at the spec sheet from your device and see which POE option you can use.

If they do not specify the PIN OUT polarity break out a multi-meter and but one end off of a patch cable and strip the wires and figure it out on your own.

Also if they have a bridge rectifier circuit like MIMOSA the device will swap the polarity the way it wants it.

WARNING - If your equipment is not specifically designed to accept power on all 4 Pairs do NOT use a VH POE option.

By using that POE tap of you try and draw more than .75A / 37.5 watts constant or 1A / 50 watts spikes you will damage the Ethernet transformer as the trans former is rated at a MAX of 1A per pair.

[sirhc]

As far as shutting down and rebooting does the radio run on Negative 48V because if it does and it bonds positive to the rail (chassis) then you create a dead short and the Netgear can be acting as an isolation to prevent the dead short from occurring.

If this is the case you would need to use our WS-26-400-IDC which has an Isolated power supply but the WS-26-400-IDC has a limited DC input range and does dot allow for all the voltage monitoring like the WS-12-250-DC but it was designed for -48V sites.

I am suprised you havent done any damage to the switch or radio if this is the case.

I think you will find the radio bonds POSITIVE which is 0V to reference in a -48V site

Break out your volt meter and do some testing here.

[Steffan]

Hi Sirhc,

That makes perfect sense, we have tested this and you are correct. Are Netonix likely to make smaller 12 port IDC switches in future?

We have a number of sites with these links that only have 4 or 5 bits of kit on them.

Kind regards

Steff

[Julian]

A 12-400-IDC has been tossed around the office a few times, can I throw you into the 'interested' column?

Physically, I don't believe it would be much smaller than the 26-port, that power supply has a fairly large footprint.

it all boils down to having the interest to justify tooling the chassis - all other parts already exist. (i.e. all it takes is money)

[Steffan]

Hi Julian,

We have found a DC/DC isolated adapters 200w but they are £130+ each, we have ordered one in to test.

Our SAF kit also works on the same principal so I bet there will be a demand.

Kind regards

Steff