Paneltronics AC load shedding, smarter power

... written for Panbo by Ben Ellison and posted on Jul 7, 2010
Paneltronics AC load shedding module.jpg

Paneltronics new load shedding system is somewhat related to my battery/monitor/charger travails.  Boaters of all sorts are struggling to manage their electrical appetites, and the line between electrical and electronic is getting fuzzy indeed.  And there are all sorts of us; I have no need for AC load shedding personally, though this device is unique in that it's aimed at boats like Gizmo...

The Paneltronics power management system is only $689 MSRP and it's only designed to manage a 30 amp shore service, shedding up to three loads before the dock circuit breaker trips and turning them back on again once the excess load has gone away (assuming, I guess, that they will go on again by themselves when power is restored).  In other words -- heat wave on the East Coast! -- you wouldn't have to get out of your deck chair after the ice-maker kicks in and knocks the AC, inverter, etc. out.  It can also manage 30 to 75 amp generator loads.
   Load shedding is already a feature of some distributed power systems, like Moritz's OctoPlex seen below, but those are whole boat systems, not add-on modules like the Paneltronics design.  And there is another approach to this issue, which is a synchronized inverter that can use a boat's batteries to get through peak loads.  I think Victron pioneered this technology, and Nigel Calder has proselytized about it in Ocean Navigator and Professional Boatbuilder.  Reducing generator size is a good thing, whether done with battery assistance or load shedding.  In fact, I heard an NPR radio interview today (available here) discussing ways whole national power systems could be made much more efficient thanks to a central systems for managing home and business loads on a grand scale.  Check out the Demand Response and Smart Grid Coalition.  Electricity is definitely getting more electronic, at all sorts of scales.

Octoplex_Load_Sharing.jpg

Posted by Ben E on July 7, 2010 7:07 PM

Comments

We just installed a new 3000 Watt Victron Inverter and it has this sort of load shedding and sharing (up to 50 amps at 110V). So now I need to figure out how to rewire our shore power to take better advantage of this for when the A/C or refer kicks on so we don't trip the breakers when stuck on a 30A shore power connection.

Posted by: Gram Schweikert at July 7, 2010 11:29 PM | Reply

This unit has been upgraded to handle 120VAC-30A and 120VAC-50A Shore Mains.
And yes, the loads are restored automatically once there is enough power available for each load. They are restored in the reverse order they were shed, so the "more important" loads come back first...

Posted by: Nestor Quiros at July 8, 2010 2:37 PM | Reply

It looks like Defender has this on an intro special for $395, which makes it seem like a pretty good option.

Posted by: Noah at July 13, 2010 2:43 PM | Reply

Moritz OctoPlex loadshedding does not exist, even though its in their brochure.

Posted by: Anonymous at July 14, 2010 8:50 PM | Reply

Gram, are you sure that new Victron actually has the load shedding capability? I bought the 3K Victron Multiplus last Novemberish, with the 50amp transfer switch. According to the Vitron brochure on the multiplus, which I studied in great detail, it was supposed to have the load shedding relay, in the box. It didn't. The printed circuit board has the slot, but the lugs are not on it.

The whole reason for purchasing a Victron unit, was to take advantage of the co-generation feature. A great thing when your 48 foot boat only has 30 amps of shore power on the dock. But, this means running the whole boat through the inverter, not just a few targeted outlets if you want to take advantage of the co-generation. The unintended consequence is to suddenly be running your whole boat, including heaters, on shore power if somebody accidentally trips over your shore power cable. Automatic load shedding is critical for the whole idea of automatic co-generation if you don't want to accidentally beat up on those brand new 1Kah battery bank you just lugged up the dock, over the rail and down into the nether regions of your vessel.

So low and behold, my nifty new Multiplus did not ship with the features Victron advertised. What did Victron do about it? Nothing.

My local authorized dealer in Seattle has worked to figure out how to add an external load shedding relay. To make a long story short, they simply used a generator module, which is a glorified relay with digital switch already in the box. But, its a $500 dollar add on and having just returned from a month long trip, I found this week upon returning that its backordered. This ordeal with Victron is going too many months. Maybe early next week I'll finally have a working unit, but its not going to be free and its going to be kluged together.

In the meanwhile, the new unit has pleasantly run my outlets with vigor and charges my bank nicely. By the time we get the Vitron fully working, my eyes are already firmly affixed on the devices Ben just brought to my attention above. Very very interesting. Maybe I won't need to trick a generator module into being a load shedding relay after all.

Anyhow...beware of Victron. Good products and technology, but apparently poor support and sketchy product brochures.


Posted by: ghostwave in reply to Gram Schweikert at August 6, 2010 3:41 PM | Reply

The Paneltronics new load shedding system looks like a very interesting concept. I think it may solve my problem. Looking to buy soon. Does anyone have any additional feedback/information on it?

Thanks!

Posted by: Kathy O'Brien at September 7, 2010 11:20 AM | Reply

Hello,

I thought I would also mention that the new ACSM digital meter from BEP has AC load shedding.

http://www.bepmarine.com/home-mainmenu-8/product-678/ac-systems-monitor-acsm-

Below is an extract from the instructions.

Configuring Loadshed relay operation.

All three ‘Current’ status pages have the ability to drive the Loadshed relay output on the back of
the meter.

This is provided so the operator can automatically drop a NON-ESSENTIAL section of their AC
loads. Preventing a current rise to a level that will overload the ships generators and cause the
Circuit Breaker to trip and lose power to all AC consumers.

Wire the Loadshed relay as per the ‘Wiring Diagram’ at the front of the booklet, please note that a
snubber diode is required to be fitted across the relay coil for inductive loads.

Each ‘Current’ status page can be set at a different level but please note the output will be active from the first ‘Loadshed’ becoming active until the last one clears.

To set the ‘Loadshed’ value, navigate to,
‘Main Menu’ > ‘Setup’ > ‘Input’ “required current status page” > ‘Settings’ > ‘Max Current’.
A default value of 40A is preset. Select ‘Max Current’ then enter then required value.

The Load shed current has two timers the first one of which to expire will activate the Load shed
relay output.

The timers begin counting at different current levels and continue to count as long as current stays above the set point. If it any point the current drops below the measuring point the timer will reset.

The first t1 begins counting as current rises above 120% of Max current. t2 begins counting when
current rises above100% of Max current.
The counter times are set to default vlaues. These can be changed by the following method.

Step 1. From the ‘AC Current Calibration’ select ‘t1 120% and/or t2 100%’.

Step 2. Use the soft keyboard to enter new timer value.

Step 3. When both the timers have been set you are able to ‘Enable Load Shed’ at the ‘Load shed’
function.

Posted by: AE at September 7, 2010 9:00 PM | Reply

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