Allegedly smart meters

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Open Neutral

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GoldDigger said:
Beyond even that, current "smart meters" use their wireless data communications capability to form themselves into a mesh network where each meter is capable of relaying the data of other smart meters until the data reaches a wireless collection point in the utility network and makes the transition to another communications channel all the way back to the central office where it is noted by the computers.
Not even a drive by is necessary except perhaps in low density/rural areas.

And, as has been noted in other threads, with that also comes the great power to remotely turn off a contactor contained in the meter and disconnect your power. Not good enough for a safety disconnect, but perfectly good for billing enforcement. AFAIK they have not gone the extra mile to install a large contactor for CT based meter installations. :)
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Yes, but... In talking with PG&E, you have to wonder...

See their electric meters do the mesh scheme, and they have regular pole-mounted nodes where they transfer to the cellular data to send the data upstream. You don't need all that many nodes that way.

Easy as pie, they have ample electricity in the meter. Their gas meters, however, use a lithium battery good for a few years. They do NOT send data to the nearest electric meter. Oh no, they need enough transmitter power to reach a node directly.

And in rural areas, where there are no nodes? They had no plans for mobile interrogators in cars; just park and walk to each meter.

I am curious about the contactors. Such also makes sense for easing the startup load when recovering from blackouts. But I wonder what design they are to NOT have large continuous currents? A mechanical latch with a 2nd, small hold-on coil maybe?
 
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GoldDigger said:
How about magnetic latching with pulsed open and close coils?

Tapatalk!
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Don't you want it to fail open? When the line drops, you want the load disconnected until Reddy Kilowatt positively commands the relay closed again.

What I envision is a dual coil contactor. One is the close coil; it's driven for n ms to restore power, then is off.

The hold coil draws a fraction of the power; it remains on until the line fails or the billing dept sends a "deadbeat" signal. When the hold coil goes off, the load contactor fails open.

Thinking out loud, the restoration SOP is the meter has a random length time before reclosure timer. This eases the startup surge. That timer might be multiple minutes long. If it's a small outage area, Reddy then might send a restore signal before the timeout. But the timer assures restoral even if the telemetry network fails.
 
We use Itron C2SOD meters here on 200A 1ph services. There are a half dozen different Itron Openway models in use here for 3ph and services >200A, but none of those have the disconnect ability. You can see how the C2SOD is assembled in this video, the contactor is shown at the 3:30 mark. Appears to be a solenoid driven wedge opening the contacts, and I've heard that the timing is coordinated to the zero-crossing of the AC waveform to minimize the arc.

 
Rampage_Rick said:
Appears to be a solenoid driven wedge opening the contacts, and I've heard that the timing is coordinated to the zero-crossing of the AC waveform to minimize the arc.
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That's interesting; and solves the issue of coil power consumption of in-use meters. The POCO can assume oh 98% of their installed meters will be on, not disconnected.

But it has the conundrum that it takes power to disconnect the power. So when relighting a dark region, all the loads will be connected until the meter wakes up and disconnects them. That must be many milliseconds at best. And a spike like that does no one any good.
 
I don't know if this is how it is done, but there is no reason a capacitor circuit couldn't be set up to open the disconnect when the power fails for a set amount of time.
 
Open Neutral said:
But it has the conundrum that it takes power to disconnect the power. So when relighting a dark region, all the loads will be connected until the meter wakes up and disconnects them. That must be many milliseconds at best. And a spike like that does no one any good.
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I would assume that the solenoid stays put (open or closed) until commanded by the meter.

To disconnect power, meter fires solenoid to drive wedge between contacts. To reconnect power, meter fires solenoid with opposite polarity to remove wedge.

I've already seen one service turned off for nonpayment. The LCD reads "CON OFF"
 
Rampage_Rick said:
To disconnect power, meter fires solenoid to drive wedge between contacts. To reconnect power, meter fires solenoid with opposite polarity to remove wedge.
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I've not seen such but it may be feasible. Has anyone seen such a design?

You then need the cap to fire off while the grid fails; so it is off at restoral.

After power is restored, it can of course fire ON.
 
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