dragonfly wrote:Just bought a bunch of these because we saw them at WISPAPALOOZA. Looked like a good replacement for a RB750UP's. But upon first opening (we actually read the docs in the box) and see that it says it's very important that you power down a port before unplugging the cable? Seriously?! It also says to test the cable first to make sure it's not shorted as it could reboot the switch. Again, Seriously?!?!
Is this just an overly conservative warning, or really how it is? If it is, we'll be returning all of these and sticking with our existing POE's and 750UP's. How disappointing!!!
There is a Polyfuse for short protection to protect a shorted cable from becoming a fire hazard but since these switches deliver HIGH POWER compared to other POE switches it can still damage a port if the cable is shorted.
But besides that if you take most any Passive POE switch and turn on 48V then plug in a dead shorted cable or crimp an END on a live cable it almost always results in the entire switch being dead and may never boot again where as with our switch you
"may" damage/fry the port you shorted
especially with 24VH or 48VH but the rest of the switch if fine (although it
"may" cause a power dip which
"could" result in the switch rebooting).
Our ports are capable of 1.5A sustained POE at 55C which you will NOT find in any other POE switch on the market
(THAT IS A CRAP LOAD OF POWER) and yes if you plug in a dead shorted cable the power draw down in amperage could cause the switch to reboot.
Remember if a port is capable if 1.5A at 55C (remember Polyfuses and how they work) that means at cooler temperatures that port could pass up to around 2 Amps and a Polyfuse is designed to handle 150% to 200% of in rush current so up to 3 Amps to 4 Amps or 150 to 200 watts. To put that into perspective a ToughSWITCH Pro 8 only has a 150 watt power supply for the entire switch.
If you upgrade the firmware to v1.3.3 POE Smart will automatically check for DEAD SHORTED cables when you go to turn POE on unless you disable the feature on the Ports Tab but it is not to be relied on as your only safety checks but is more to protect you in-case you put up a new cable and punch it down wrong and forget to first check your work.
But if you turn on POE for a port before you plug in your cable then POE Smart is by-passed, or if you crimp a live cable POE Smart will not protect you as power is already turned on for that port and POE Smart only checks the cable when you first select a POE option for a port then click Save/Apply. Once POE is already turned ON for a port then POE Smart is bypassed if you then plug in a cable as the port was already checked when you first turned the POE ON for that port.
dragonfly wrote:All POE switches we have ever worked with can detect when to power up/down a port. They also have short protection. What if a climber chops off a connector to replace it without first remembering to power down the port? The whole site reboots?
Are you freaken kidding me? These are PASSIVE POE which means if POE is turned on then the POE power is ON. If you crimp an end on a LIVE cable you will probably fry the port as that shorts all 8 pins together - A DEAD SHORT!!!
Now "ACTIVE" POE which is 802.3.af/at leaves the power turned OFF until it negotiates with the device then turns it on, this is not ACTIVE POE.
With an active POE switch you can crimp ends on live ports as active POE only turns power on after it negotiates which means the cable checked out but then again you can NOT power airMAX or airFIBER devices with "active" POE you need "passive" POE and with passive POE you need to be more careful.
RB750UP's can not power airFIBER devices and other HIGH power needs.
So no, you can not turn POE on a port then expect to cut live wires and then crimp ends on unless you want to fry the port and that type of damage is NOT covered under warranty.
I have NEVER heard of any passive POE switch manufacturer that condones cutting and crimping LIVE ports, THAT IS INSANE, especially a port capable of delivering 1.5 to 2 Amps at 55C or 100 watts (2x in-rush), that type of power on a dead shorted cable could also damage the Ethernet cable itself.
I have never been able to find an Ethernet Transformer that can handle that much power. We have the highest rated ones we could find and they are only rated at 1 Amp per pair so there is a good change that Polyfuse will not POP before the Transformer Pops.
Yes, we are telling you to NOT plug in cables on live ports for your protection because if the cable is crimped wrong causing a short or you short the cable it "will" result in damage to the port and that damage will not be covered under warranty.
Yes, we are telling you it is not very smart to cut and crimp ends on cables that have LIVE "Passive" POE on them.
Yes, we are saying that a DEAD SHORT on a port capable of 1.5A to 2A with an in-rush capacity of 3A to 4A may result in a momentary power drop that
"might" cause the switch to reboot and or damage/fry the Ethernet Transformer.
So yes we HIGHLY recommend never plugging in LIVE POE ports especially cables that you have not tested for cross shorts such as a newly ran cable.
Pretty much that is what we are saying.