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Anyone run an HP2620 switch on DC?

Posted: Mon Jan 06, 2014 10:46 am
by RF1
I have an application to run an HP2620-24 switch at a site. Anyone ever run one off of DC? We have 12-48 VDC available.
UPS is not an option.

Re: Anyone run an HP2620 switch on DC?

Posted: Mon Jan 06, 2014 2:22 pm
by wavetar
According to the specs, it's AC only:

http://www8.hp.com/ca/en/products/netwo ... !tab=specs

So, you'll have to use an inverter of some type. Your local electronics supply store should have a variety of models on hand. Otherwise, Absopulse makes some nice stuff:

http://www.absopulse.com/Absopulse_Sine ... erters.php

Re: Anyone run an HP2620 switch on DC?

Posted: Mon Jan 06, 2014 5:28 pm
by RF1
Thanks for the quick reply.
I was hoping to find a more efficient method than an inverter so that we didn't have to add additional batteries at the site.

Re: Anyone run an HP2620 switch on DC?

Posted: Mon Jan 06, 2014 11:13 pm
by Bill_G
Is there something special about the HP that you need? Otherwise, there are DC powered 24 port switches available.

Re: Anyone run an HP2620 switch on DC?

Posted: Tue Jan 07, 2014 5:50 pm
by RF1
Unfortunately this switch is required for certification by Motorola. More than likely HP converts the AC to a workable DC voltage inside.

Re: Anyone run an HP2620 switch on DC?

Posted: Tue Jan 07, 2014 7:04 pm
by Jim202
Have you considered getting inside the device and see what voltage it runs on?

Then provide a tap into the location for an external power source.

Jim

Re: Anyone run an HP2620 switch on DC?

Posted: Tue Jan 07, 2014 8:18 pm
by Bill_G
Jim202 wrote:Have you considered getting inside the device and see what voltage it runs on?

Then provide a tap into the location for an external power source.

Jim
I've done that on switches that use an external power supply that is non-standard like 8 or 15 volts - open up the case to look at the reg so I can read up on the device's input rating. Often, they are rated for 7 to 24V input to provide 5V at x amps, and the weird wall wart they provided was just something they bought with the correct molded plug. Almost anything would have worked. So, I cut the cord off the wall wart, and run it to a circuit breaker off a dc/dc converter that may or may not be already present to run other equipment.

If this HP is AC only, maybe it's modular, and maybe the power supply can be easily exchanged. In that case, I'd be tempted to find the switcher output before the regs to measure the voltage. Hopefully it lands someplace a dc/dc can produce, and hopefully they use brute force regulators, and not some strange DC feedback to the switching oscillator. Pull the AC line input fuses, cut the traces from the switcher output, hack the housing, put some kind of a connector on, and wire it up to the voltages available. And cross your fingers the thing never dies.

The safest bet in this situation is a DC/AC converter, and add batteries to the pile for this one device. I've had to do it in the past just to run modems because the OEM did not have a DC option. Wiltron and Newmar both make good stable long lasting reasonably efficient converters.

Re: Anyone run an HP2620 switch on DC?

Posted: Tue Jan 07, 2014 8:20 pm
by Bill_G
Jim202 wrote:Have you considered getting inside the device and see what voltage it runs on?

Then provide a tap into the location for an external power source.

Jim
Rats. Talk to the PM, and make a recommendation for a different model. Explain the problem, and have him forward the request to MOT engineering. Make them provide the solution since they are making the requirement.