How to properly distribute the network load in a country house

Own­ers of coun­try cot­tages often face the prob­lem of over­load­ing a low-pow­er dacha net­work that occurs when con­nect­ing var­i­ous pow­er­ful equip­ment. Espe­cial­ly often there is an over­load of the net­work in the cold sea­son, when heat­ing devices are added to the elec­tri­cal equip­ment. A fre­quent prob­lem is the shut­down of the intro­duc­to­ry cir­cuit break­er due to over­load. You can solve the prob­lem with the help of a spe­cial device — a non-pri­or­i­ty load dis­con­nect relay.

These relays allow you to increase the num­ber of con­sumers with­out exceed­ing the per­mit­ted pow­er, and, con­se­quent­ly, with­out turn­ing off the input cir­cuit break­er. They are installed in the shield, and elec­tri­cal cir­cuits are con­nect­ed to them, to which var­i­ous con­sumers are con­nect­ed, divid­ed into two groups:

  • pri­or­i­ty (cir­cuit sup­ply­ing elec­tric­i­ty to light­ing, refrig­er­a­tor, etc.), which should not be turned off under any cir­cum­stances;
  • non-pri­or­i­ty (under­floor heat­ing, stor­age water heater, elec­tric heaters, etc.), which allows short-term inter­rup­tions in pow­er sup­ply.

Sim­i­lar non-pri­or­i­ty load dis­con­nect relays are avail­able from a num­ber of large man­u­fac­tur­ers, such as Schnei­der Elec­tric, ABB, Legrand.

How does a non-pri­or­i­ty load shed­ding relay work? Con­sid­er the exam­ple of the updat­ed line of Legrand non-pri­or­i­ty load relays (in the fig­ure). A sin­gle-phase relay for cur­rents up to 28 A con­tin­u­ous­ly mon­i­tors the cur­rent flow­ing through it (and, accord­ing­ly, the pow­er con­sumed) and turns off a non-pri­or­i­ty load, for exam­ple, a con­vec­tor, if both burn­ers of the elec­tric stove are turned on at the same time and the pow­er exceeds the set val­ue of 3.68 kW. As soon as one of the burn­ers turns off, the elec­tric con­vec­tor turns on, etc. Thus, the relay allows the use of devices with a total pow­er of 5 kW, with a lim­it of 3.68 kW. The pow­er lim­it can be changed in the range from 0 to 6.5 kW in steps of 0.01 kW. At the same time, an adjustable time delay from 0 to 999 s is pro­vid­ed. to enable/disable non-pri­or­i­ty load. The max­i­mum cur­rent of the non-pri­or­i­ty load dis­con­nect con­tact is 16 A (4 kW). The relay is equipped with a unit for mea­sur­ing pow­er, cur­rent and volt­age. Infor­ma­tion is dis­played on the LCD dis­play.

In the case when it is required to con­trol cur­rents of more than 28 A or when a three-phase pow­er sup­ply sys­tem is used at home, it is advis­able to use a uni­ver­sal relay that can oper­ate in both sin­gle-phase and three-phase cir­cuits. In sin­gle-phase mode, non-pri­or­i­ty loads are divid­ed into three groups. If the total cur­rent of the pri­or­i­ty and non-pri­or­i­ty loads exceeds the set lim­it, the con­sumers con­nect­ed through the relay con­tacts S1 and S2 are first switched off. If at the same time the total cur­rent still exceeds the spec­i­fied lim­it, then the con­sumers con­nect­ed to the relay con­tact S3 are switched off. With a decrease in the total load, con­sumers of the third group will be con­nect­ed first of all, and then, if there is a pow­er reserve, con­sumers of the first and sec­ond groups.

The max­i­mum load on the con­tacts of the relay of non-pri­or­i­ty loads is 15A.

The prin­ci­ple of oper­a­tion remains the same, how­ev­er, it is pos­si­ble to choose an algo­rithm for dis­con­nect­ing non-pri­or­i­ty loads. Either all three groups are switched off at the same time, when the thresh­old val­ue of the total cur­rent in one of the phas­es is exceed­ed, or each group will be switched off depend­ing on the load in a par­tic­u­lar phase.

Benefits provided by non-priority load shedding relays:

  • Increase in the num­ber of con­sumers with­out chang­ing the allo­cat­ed pow­er and increas­ing the cross sec­tion of the input cable;
  • Pre­ven­tion of dis­con­nec­tion of the intro­duc­to­ry cir­cuit break­er due to over­load;
  • Sav­ing ener­gy by reduc­ing loss­es in the sup­ply line.

Load Sharing Relay Wiring Diagram

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