[RE-wrenches] wireless relays for load shedding?

[Dana]

Wireless - I have no clue but - Simplest thing that comes to mind is spring wound timers on the infrared lamps & clock timers.

Spring wound timers come in lots of “length of time options”

Could the hot tubs have a “Use schedule” to coincide with the clock settings?

 

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Dana Orzel                              Great Solar Works, Inc. 

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Idaho Contractor - # 028765         Idaho PV # 028374

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From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> On Behalf Of Eric Youngren
Sent: Wednesday, May 23, 2018 1:28 PM
To: RE-wrenches <RE-wrenches at lists.re-wrenches.org>
Subject: [RE-wrenches] wireless relays for load shedding?

 

Howdy Wrenches,

 

I'm working on a generator powered mini-grid for an island fishing resort in Alaska. They have 3 XW6048 inverter/chargers to charge batteries while the diesel runs and power the loads from the batteries when the diesel shuts down.  

 

They have several high power heating loads not typically seen in battery-based off-grid electrical systems. Two 4kW hot tub heaters and six 1kW infrared space heaters.  We have the 46 kW generator run-times set so that the infrared heaters are (in theory) powered only while the generator is running, but the hot tubs are thermostatically controlled and cycle on and off every 4-5 hours or so.  

 

I want to make it so that these big heating loads can never be powered from the batteries, and will only come on while the generator is running.  The current plan is to use the Auxillary output 12V terminals from one of the XWs to control power relays to switch the hot tub circuits, based on battery voltage triggers. One of those hot tub circuits is fed from the main panel right next to the inverters so that is easy enough.  But the other hot tub is fed from a sub-panel located in a different building around 200 feet away from the inverters. Pulling a pair of wires to control the second relay at that sub-panel is not practical.  So, I'm looking for wireless options that could control a power relay for the hot tub circuit in the remote sub-panel. Ideally, the control signal would come from the same AUX terminal so both hot tubs will not receive power when the battery voltage is below 50 volts or so, which would indicate that the generator is not running.  

 

I would also like to put the infrared heaters on a similar control system so that we are not dependent on people remembering to switch off the heaters before the generator shuts down.  

 

Has any of you done this kind of thing?  Any suggestions on equipment or best practices?  THANKS!

 

Eric Youngren

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