LLG-5 zero sequence power relay (hereinafter referred to as the relay) is used as a directional component for protecting against grounding short circuits in high current grounded power grids.

2、 Working principle
This relay adopts a rectification type phase sensitive structure, as shown in Figure 1.

3、 Technical requirements for LLG-5 zero sequence power relay
1. Rated value:
Communication: Current 5A, 1A, voltage 100V, frequency 50Hz.
DC: 220V; 110V.
2. Maximum sensitivity angle
Current Ip (-3Io) lagging voltage Up (3Uo)
φm＝80o±4o
3. Action power:
When φ m=80o Up=1.5V, it is less than 2.0VA.
4. Action time at 4 times action power: less than 25mS through diode outlet. Less than 35mS through intermediate relay outlet.
5. Rated power consumption:
Under rated current and voltage: the AC current circuit shall not exceed 1.5VA.
The AC voltage circuit shall not exceed 70VA.
6. Return coefficient: The return coefficient of the relay is greater than 0.5.
Except for diodes and polarized relays, all circuits of the relay can withstand an AC voltage of 2000V for 50 cycles on the insulation of the casing for a 1-minute test.