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Current Relay of Ground Protection


AL-4 - current relay of ground protection

The current relay AL-4 is the relay of current with ground protection which is not slowed down, but at the same time it is highly sensitive with one current chain. The device is used with the current transformer of the zero sequence in schemes of protection against short circuit to the earth of the generators, engines and lines with small currents of short circuit to the earth and in other devices of relay protection, antiemergency and industrial automatic equipment.

Average main error of actuating current in any digitized point of a scale doesn't exceed 10% of a setting for the AL-4 relay.

Current variation (calculated as a percentage of the average value of the actuating current) must not exceed 2,5 %.


Technical characteristics

Rated current, А The range of the settings of actuating current, А Discrete step Relay power consumption in current circuits, VА, not more than, at current value Relay power consumption in the circuit of operational supply voltage, VА (W), not more than Thermal stability, А
I=Iaverage.min I=Irated For a long time Within 1 s
0,16 0,005 - 0,150 0,0015 0,1 0,2 6,5(10) 0,16 30


Main parameters

Rated supply voltage: AC 110V; 220V
DC 100V; 220 V
(in the same version)
Relay actuating time, not more than: at current value 1,2 Iaverage / 3 Iaverage 0,06 / 0,04 s
Quantity/type of the contacts 1 change-over contact
Electrical endurance, not less 20 000 cycles
Mechanical durability, not less 100 000 cycles
Accuracy class 5
Reset factor, not less 0,93
Protection level: relay / terminal board IP40 / IP10
Operating temperature range –40...+55 ˚С
Weight, not more than 0,8 kg

Allowable limits of operational supply voltage are within 0,8 … 1,1 of nominal one.

The contacts of the relay AL-4 provide commutation of the current (not more than 2,5 A at voltage of 24…250 V). At the same time the disconnected power:
     - in AC circuit: not more than 300 VA at cosφ ≥ 0,5;
     - in DC circuit: 60 W at t≤0,02 s.

AL-1 - chart of functioning AL-4 - scheme of connection
Chart of functioning
Scheme of connection
AL-4 - outside dimensions
Outside dimensions