Reactron energizer: Interruptible Power Supply

Description

Uninterruptible power supplies are indispensable. But even more useful is an interruptible power supply (with UPS on a microcontroller, for smart interruption and status reporting). Control of individual ports allows intelligent remote control of power supply, and the ability to rapidly cut power in an emergency.

The UPS allows continuous power to an ATMega328P-based controller, which can trigger solid state relays that allows the AC power to flow or to be cut, to a few individual outlets. A HopeRF transceiver allows the UPS (now, an IPS) to be commanded wirelessly.

Control of individual power ports allows for emergency shutdown in timed sequences, if desired. However, this object may simply be used for manual power control, if that is desired.

Details

This is a wirelessly controlled UPS with control over individual power ports. It integrates into the wireless Reactron network for intelligent control. In the image below we see the original UPS board at the top, and an additional relay board in the space just left of center. This board has three sold state relays, each tied to a different power port, and allows battery backed up power to flow (or not). The board takes a standardized Reactron board with ATMega328P and HopeRF transceiver to allow remote wireless control, In this image, the Reactron board is the reddish board seen on edge, below and to the left of the three-port blue connector.

Here is a closeup of the relay board:

The headers on the right hand side are where the microcontroller board attaches.

As an example of usage, consider a CNC mill undergoing some sort of undesired operation. Cutting all power to all components at once may result in machine damage, or may create new, unsafe conditions. It may be best to cut all positioning motor movements first, then the spindle, then the computer controller, then the flying vision system, then the dust collection.

If an end mill is traversing through a material but there is a problem, if all power is cut at once, the end mill may shatter (complete with flying shards), the spindle may be bent, gantry misalignments ensue, etc. It is better to shut the gantry motors down first, so that the tool position comes to a halt before spinning down the end mill. It is better to have a cutting tool be able to cut through the material a short distance than to try to fight its way through with sheer pressure. Once the positioning motors are shut down, the spindle may follow immediately, then the controller computer may be shut down, then other supporting equipment, to remove all electricity from the machine enclosure in the case of emergency. The sequence may take only a fraction of a second, but it avoids tool and material shard projectiles from uncontrolled emergency shutdown. It is preferable not to exacerbate an emergency condition by compounding it.

Secondarily, it also may prevent machine damage and the costs associated with downtime and parts replacement.

Wireless control means that any conditions warranting power shutdown can come from a complex variety of sources, such as an external system processing verbal commands, an energy-conscious system monitoring power consumption in idle times of connected devices, or a remote system manually controlling the power state. The microcontroller on the UPS is resilient to power failure, and will be able to transmit the state of the power ports back to any requesting system. (“Did I leave the oven on?”, one hour after leaving the house… “No, you did not.” OK good, now I can relax. Or, “Yes you did” - OK then, shut it down now.)

A lot of possibilities exist with just a simple controllable power gate, as one unit in a larger system. One may use voice control to stop a machine in an emergency or other condition, from wherever one may be in the room... or from anywhere on the earth, where an input to the control network exists. On its own, it is still useful, and may be controlled via web page for simple remote control.

More details to come in the logs...

Project Logs

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Visual indicators
Kenji Larsen • 06/30/2014 at 02:44 • 0 comments

Here are some photographs of a recently completed build.
In this one, I added LED indicators to the switched outlets.
I did this because sometimes something is not working as expected, and I actually go over and stick mulitmeter probes into the sockets in question. (Is it plugged in? I start there - sometimes, it is actually that simple!) But as I was writing up this recent build, I realized, that really is silly - the same digital output that triggers the solid state relays can also handle a tiny amount of extra current to light up an LED. Then I know what is happening with the microcontroller visually and directly, without having to query its RF interface to ask it what state it is in (or thinks it is in). Sure, maybe the SSR fried or something, but >99% of the time, whatever is wrong has nothing to do with the actual power transmission working properly. So for that great proportion of the time, these LEDs will work out just fine, and can be seen from across the room. It's a simple time saver, and that is what all of this is about.
What you see in the image are three yellow lights, and one green one.
The green LED is drawing current from a digital output pin not tied to an SSR. I just make the microcontroller turn it on, when it initializes, so I know there is power and the code is running. The pair of outlets it is matched with is a "generally on" set of outlets, UPS power as per the original UPS design. This power drives the microcontroller and the relays, so if the light is not on, none of the lights will be on (unless something is very wrong, which would be great to know, too). If there is no light, there is probably no mains power. Or the microcontroller or relay board (which has the AC to DC power supply for the microcontroller) is fried. So far that has not happened. Anyway, I can still use the original LED next to the power button to indicate the UPS is functioning, and there should be power to that outlet set.
The three yellow lights are matched to two single outlets and a pair of outlets ganged together. These are the SSR-switchable outlets. The LED, when lit, indicates that the digital input to the SSR is high, and the SSR should be passing AC.
The two outlets at the top are not-switched, not-UPS protected outlets that are just surge protected mains outlets.
To add the LEDs, I soldered resistors inline and heat shrunk them, so that the different colors could just be plugged into the microprocessor's 3.3V output.
I drilled some 3mm holes and simply hot glued them in from the back. Fortunately, the manufacturer of this UPS left me about a quarter inch of space under the battery. I took a sharp knife and carved out some reliefs in some of the ribs to route the wires. Also visible in the above picture is the 4 conductor programming header wire, which I snake out into the battery compartment. I sometimes need to re-flash the chip with updates, and my implementation of wireless programming is still being refined. The loop of yellow wire that terminates in red heat shrink tube is the antenna for the HopeRF radio.
On the back of the relay board I just soldered the LED wires to the 4 digital output pins. There is a bit of clear heat shrink tubing on the cluster of wires to protect them from the header points, which might be bumpy, and as these units get moved around a lot, will help insulate the wires from wear against these points. There is hot glue covering the wires as well, to immobilize them.
With the back on, it's just waiting to accept the battery. The programming header is visible, but it tucks out of the way.
The three outlet sets indicated by yellow LEDs are individually controllable, via commands coming in over RF. Here is outlet 2 off:
And outlets 2 and 3 off:
I guess that is not so exciting on its own, but that is OK with me. The exciting part is how it integrates, as simple as it is, with...
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Retrospective: Earlier model (sort of)
Kenji Larsen • 06/16/2014 at 03:18 • 0 comments

Here's essentially the same thing but with only one port, and no UPS. It is basically just a wireless 120VAC relay with a manual override (the switch). The case is just a regular blue PVC electrical box. Simple, but served me well for a long time.
The relay board is just visible inside, without taking it all apart to photograph it....
This worked well, but I do like the UPS on the microcontroller. Of course, this whole small unit could be plugged into a regular UPS. Still, it only had one port (the two outlets are bridged).