[177613] in North American Network Operators' Group
Re: PDU for high amp 48Vdc
daemon@ATHENA.MIT.EDU (Bill Woodcock)
Wed Jan 28 22:21:39 2015
X-Original-To: nanog@nanog.org
From: "Bill Woodcock" <woody@pch.net>
In-Reply-To: <54C99D18.5070907@direcpath.com>
Date: Wed, 28 Jan 2015 19:21:25 -0800
To: Robert Drake <rdrake@direcpath.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
The rotary actuators are an off-the-shelf item for transfer switches. No pr=
oblem to get them paired with high-amperage switches. But a contactor, which=
is a solenoid-driven switch, is also an off-the-shelf item. The ones I use i=
n EV applications are rated for 1000A, and cost about $300. You need to be c=
areful to look at the trade-off between voltage, amperage, and the per-cycle=
probability of a weld, though. An over-rated contactor helps a lot if you'=
re going to be cycling it a lot, whereas if it's for emergency use only, you=
can hew a lot closer to the max rating.=20
=20
-Bill
> On Jan 28, 2015, at 18:40, Robert Drake <rdrake@direcpath.com> wrote:
>=20
> For larger DC devices with ~50amps per side, does anyone have a software a=
ccessible way to turn off power?
>=20
> I've looked into PDU's but the ones I find have a max of 10amps.
>=20
> I've considered building something with solenoids or a rotary actuator tha=
t would turn the switches on or off, but that's a complete one-off and would=
need to be done for each device we manage (not to mention it involves janky=
wiring all over the place I've got to explain to the colo)
>=20
> My use case is pretty infrequent so it needs to be remote-hands cheap.. it=
's for emergencies when you need to completely power cycle a redundantly pow=
ered DC device. The last time I needed this it was because a router was stu=
ck in a boot loop due to a bad IOS upgrade and wouldn't break to rommon sinc=
e it had been >60 seconds. It came up again tonight because we wanted to di=
sable one power supply to troubleshoot something.
>=20
> FWIW, I believe I've seen newer Cisco gear with high-end power supplies th=
at have a console or ethernet port which would possibly let you shut them do=
wn remotely. That solves the problem nicely if you're dealing with only one=
bit of hardware, but I'd like a general solution that worked with any vendo=
r. Possibly a fuse panel with solenoids that could add/remove fuses when ne=
eded.. or would that be considered dangerous in code-ways or in telco fire r=
egulation ways?
>=20
>=20
>=20
>=20
