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Hi there!! I am an electrical contractor from South-Africa. I have a client that recently installed a 19kva three phase 380/220v back-up generator, on the main feed to his property. The property exists out of one large house and 11 flats. On the property there are 11 stoves and 7 water heaters. The total load on the property is borders the maximum output of the generator.

The client wants me to install a system which will be able to switch off all the water heaters automatically when the generator kicks in. I was thinking of something along the line of - remote control, frequency operated, load control relay's (as used by utilities) but don't where to find something like that. Any ideas?
 

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What if each of those water heater circuits was put on a contactor whose coil is energised by a circuit that does NOT receive power from the backup generator? If the power fails and the generator comes on, the lighting and other things continue to work but the water heater contactors release and turn them off.
 

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Do each of the remote buildings have phones? use an auto dailer keyed to the ATS, signals the h20 heaters to shut down by vintage's contactor.
 

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That's alot of contactors to cut into the existing panels... Sounds like you don't have a choice there.

My first reaction is to install contactors with 24vac coils and use DDC wireless network controllers. On second thought, maybe some X10 type of system is the answer, they use that comm over powerline protocol.
 

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Functional Devices has a wireless RIB,

but I am thinking that you want to have status points that monitor the load side of the contactor to ensure that none of the more studious tenants is bypassing your load shedding scheme. I don't know anything about LON, but LON might be the most cost effective answer. Any Bacnet system is going to bring the local dealer into the picture which will be expensive.
 

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That's alot of contactors to cut into the existing panels... Sounds like you don't have a choice there.

My first reaction is to install contactors with 24vac coils and use DDC wireless network controllers. On second thought, maybe some X10 type of system is the answer, they use that comm over powerline protocol.
I like the idea of an IP enabled controler. It would allow you to add or remove loads as needed. Even monitor power quality, Load in real time, etc and could be made programmable to whatever degree you wish.
 

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There might be a circuitbreaker, similar to SquareD's power-logic, which could dump the loads.

But that sh1ts going to be mad expensive!!
 

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I would probably go with small PLCs with modbus communicating over a radios. Put the master the generator and a slave in each house. When line power goes down the master writes to the slaves and turns off the heaters.
 

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How about a shunt trip breaker for the Heaters, fed from the genset output.
As soon as the generator turns on, it will shunt the breakers.
 

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There might be a circuitbreaker, similar to SquareD's power-logic, which could dump the loads.

But that sh1ts going to be mad expensive!!
It may be cheaper to put a series of smaller generators and shed the loads at the switch. But I'm thinking an estate this size may want some options.
 
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