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Selectively switch off power consumers when the voltage falls below a minimum

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Updated – December 29, 2022

In order to selectively switch off power consumers when the voltage falls below a minimum, a Homematic DIN rail switching actuator with power measurement is required.

  • Homematic DIN rail switching actuator with power measurement HM-ES-PMSw1-DR

The Dometic refrigerators give an acoustic warning signal when the AC supply voltage drops from the usual 230 V to below 195 V. This can be the case when using 25 or 50 m cable drums or a generally weak supply network. Larger consumers then quickly cause a voltage drop, which leads to the acoustic warning.

Dometic has kindly designed the refrigerator's circuit so that after disconnecting the 230 V supply voltage and reconnecting it, the refrigerator immediately resumes its 230 V operation.

Since in the above listed Performance measurement script HG_LM also the voltage across the variable Var_HG_LM_VOLTAGE can be queried, simply inserting the following code into the elseif-branches in the above script HM_LSS, by means of the top-hat rail switching actuator looped into the phase of the refrigerator HM-LC-Sw1-DRto turn the refrigerator on or off.

The code is:

! Refrigerator OFF
if (Var_HG_LM_VOLTAGE < 200)
{
dom.GetObject("BidCos-RF.SEQ3114635:1.STATE").State(0);
WriteLine("Refrigerator OFF");WriteLine(Var_HG_LM_VOLTAGE);
}

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